The two dry batteries for the motor are held in two tin troughs, as illustrated in Fig. 92. These troughs are fastened to the side of the boat by means of small bolts. They will prevent the boat from shifting its cargo; in other words, they hold the batteries in place and thereby prevent the boat from listing.
The deck and deck fittings should now be furnished. The construction of the forward cabin is shown in Fig. 93. The sides and back are formed with cigar-box wood, while the curved front can best be made with a piece of tin. The top is also cut to shape from cigar-box wood, and should overlap about 1/4 inch. The pilot-house is simplicity itself, being made of a piece of curved tin with three windows cut in it. Four little lugs cut in the tin are bent on the inside and each provided with a hole. These lugs are used to tack the pilot-house to the deck. A small skylight is produced from a solid piece of wood and tacked in place as illustrated in the drawing.
The builder is cautioned not to destroy the appearance of his boat by making the mast too large. After the mast has been nicely sandpapered, a little wire frame is bent to shape and fastened to the top, as shown in Fig. 87. The little wire railing that is placed in front of the mast is then bent to shape, and this and the mast are put in their permanent position. The mast can be held to the deck by boring a hole a little under size and smearing the bottom of the mast with a little glue before it is forced in. Pieces of black thread are run from the top of the mast to the railing at the bottom, as shown. These threads are used to hoist signal flags. Two little angle-pieces are placed on the forward deck, one on each side of the pilot-house. These are for the harbor lights. One should be painted green and one red.
This finishes the forward cabin. It should be placed in the center of the deck and the position it occupies should be marked out with a pencil. This portion of the deck should be carefully cut out with a coping-saw. The cabin is then forced into the opening. The fit should be fairly tight, so that it will not be necessary to employ nails or glue, as this is the only way in which the interior of the hull is made accessible.
Two ventilators are placed just back of the forward cabin. Between the forward cabin and the cabin aft there is placed a rapid-fire gun. The details of this gun are given in Fig. 94. The barrel of the gun is made of a piece of brass rod. A hole is drilled through this rod with a small drill and a piece of copper wire is inserted. A square piece of brass for the breech is then drilled out to receive the barrel. One end of the barrel is placed in this hole and held with a drop of solder. A drop of solder should also be used on the copper wire that runs through the barrel. The bearing and shield of the gun are made from thin sheet brass, as illustrated. Three holes are drilled in the bearing bracket, two through which the wire passes and one through which the small nail is placed to hold the bearing to the wooden standard. The shield is forced over the barrel and held in place with a drop of solder. When the barrel is mounted in the bearing, a drop of solder should be put in place to prevent the barrel of the gun from tipping.
The cabin which is placed aft on the boat, is of very simple construction. It is made up entirely of cigar-box wood tacked together, and the top should overlap 1/4 inch. The cabin is then tacked to the deck of the boat. The mast should be only three-fourths as high as the forward mast, and a tiny hole is drilled near the top. Into this hole a small piece of soft wire is placed, and from this wire a thread runs to the cabin. A small flag can then be placed on the thread, as illustrated in Fig. 86.
Six port-holes are now bored in each side of the hull with a 1/2-inch bit. These can be backed up with mica or celluloid. Five smaller port-holes made with a 1/4-inch drill are then bored in each side of the forward cabin. Three are placed in the aft cabin.
With the exception of painting, the hull is now ready to be launched. Before finally applying the paint the hull should be given a thorough rubbing with sandpaper. A battleship gray with maroon trimmings makes a pleasing color combination for this boat.
THE model boat builder generally has some trouble in producing the necessary fittings for his boats. It is practically impossible to buy such things in this country, and so it is necessary to make them.
Using a little care, it is possible to make presentable fittings by utilizing odds and ends found about the household and shop. In this Chapter the author will describe the construction of the more important fittings necessary to model boats, such as stacks, searchlights, bollards, cowl-ventilators, davits, and binnacles.
The smokestack is probably one of the easiest things to produce. A very suitable method of producing a smokestack is shown in Fig. 95. The stack itself is cut from a piece of thin brass tubing. It is also possible to use a small tin can of the proper diameter. In both cases, of course, paint must be applied to improve the appearance of the brass or tin. If the stack is painted either gray or white a red band near the top of the stack produces a good finish and makes it look more shipshape.
The method of anchoring the stack to the deck of the boat is shown very clearly. First a block of wood is cut about the same diameter as the internal diameter of the stack. This block of wood is then forced up into the stack. A small square base is then cut, and fastened to the block on the inside of the stack with a wood-screw. It might be mentioned here that it is often necessary to drill a hole with a small hand drill before driving the screw in, to prevent splitting the wood.
After the base piece is fastened to the stack, the base in turn is held to the deck of the boat by two small screws driven up from beneath. The guy-wires can then be fastened on. The guy-wires should be made of very fine wire, since heavy wire would be entirely out of proportion. The wire can be fastened on the stack by drilling a tiny hole through the stack. A knot is then tied in one end of the wire, and the opposite end threaded through the hole. Small screw-eyes driven into the base piece are used to anchor the guy-wires.
Ventilators are a very important part of the boat. The model-builder will encounter considerable trouble if he attempts to make his cowl-ventilator from metal, unless he is very experienced in drawing copper out by hand. The writer has found a method of producing cowl-ventilators by the use of clay pipes. Clay pipes can be purchased for a few cents each, and when cut down as shown in Fig. 96 they form very suitable ventilators. The pipe can be cut as shown by the use of a file. The ventilator is held to the deck of the boat by being forced into a hole in the deck that is just a trifle under size. Of course, the forcing will have to be done carefully to prevent the stem from cracking. The inside of the ventilator should always be painted red, and the outside should be the same color as the boat. Ventilators made in this way absolutely defy detection and do much toward bettering the general appearance of the craft upon which they are used.
A simple searchlight, easily made by the model boat builder, is shown in Fig. 97. This is an electric light, and the batteries used to propel the boat can be used for the light. First a small circular piece of wood is cut out, as shown at A, Fig. 97. The center of this is drilled out to accommodate a small flashlight bulb. A tiny brass screw is then driven into the piece of wood, so that it will come in contact with the center of the base of the flashlight bulb. This little screw forms one of the electrical contacts, and one of the wires from the battery is attached to it.
A little strip of brass is then cut as shown in B, Fig. 97, and provided with three holes, one hole at each end and one in the middle. The brass is bent into a semicircular shape, so that it will be just a little larger in diameter than the outside of the wooden piece in which the flashlight bulb is mounted. This little piece is then fastened to a wooden post with a small brass pin, as shown in Fig. 97. Two more pins are used to hold the wooden piece to the searchlight proper. One of these pins is driven through the wooden piece until it comes in contact with the base of the flashlight bulb. This forms the other electrical connection, and the second feed wire from the battery can be attached to the little brass piece that holds the searchlight. Both the feed wires from the battery can come up through a hole in the deck close to the wooden post upon which the searchlight is mounted.
Bollards are very easily made. Reference to Fig. 98 will make this clear. First a little strip of brass is cut, and this is drilled as shown with two holes, one at each end and two smaller holes in the center. Two little circular pieces of wood are then cut, with a hole through the center. A brass screw passes through these and into the deck of the boat. The brass screw should not be driven in too far, since the bollards should be free to revolve. It is also possible to use brass tubing instead of wood if the proper size is in the model-builder's shop.
A word will be said here about finishing the deck of a model boat. It is a very tedious job to cut separate planks to form the deck. In fact, this job is quite beyond the ability, to say nothing of the patience, of the average young model-builder. A very simple method of producing imitation planking is shown in Fig. 99. A sharp knife and a straight-edge are the only tools for this work. The straight-edge is merely used to guide the knife. The cuts should not be made too deep, and they should be made a uniform distance apart. When the deck is finished in this manner and varnished over, a very pleasing effect is produced. In fact, if the work is done carefully, the deck looks very much as if it were planked.
A small life-boat is shown in Fig. 100. This can easily be carved to shape from a small piece of soft white pine. The center is gouged out, and tiny little seats made of thin strips of wood are glued in place. Two small screw-eyes are placed in the boat, for fastening it to the davits. The davits are shown in Fig. 101, at A and B. They are made by bending a piece of small brass rod, as shown. One end of the rod is hammered flat, and a hole is made in it with a very small drill. Holes a little under size are drilled in the deck, and the davits are forced into these. The method of suspending the life-boat from the davits is shown at B, Fig. 101. The little blocks of wood are glued on to a thread to represent pulleys, and they are, of course, only imitation or dummy pulleys.
The method of producing port-holes is shown in Fig. 102. A hole is first bored through the wood with a bit of the proper size. The size of the port-holes depends entirely upon the size of the boat. A piece of brass tubing is then cut off with a hacksaw to form a brass bushing. The outside diameter of this tubing should be the same as the size of the bit used. For instance, if a 1/2-inch bit is used, brass tubing 1/2 inch in diameter should be purchased. Such tubing can be obtained from any hardware store. Celluloid, such as that used for windows in automobile curtains, is glued to the inside of the port-holes. This makes a splendid substitute for glass. It can be obtained at garages and automobile supply stores for a few cents a square foot. The model boat builder can also use either mica or glass for this purpose, although thick glass looks somewhat out of place.
A binnacle is shown in Fig. 103. This is made from a solid piece of wood cut with a semi-spherical top. The steering-wheel is made of a wheel from an old alarm clock. The teeth of the wheel should be filed off. Tiny pieces of wire are then soldered in place on the wheel, as shown. A pin driven through the center of the steering-wheel is used to fasten it to the binnacle. The binnacle itself can be held to the deck either by glue or by a small screw.
A torpedo-tube for use on model destroyers and battleships is shown in Fig. 104. First two disks of wood are cut. Then a circular piece is cut, as shown. Two brass nails are then driven through this piece into one of the disks. An upholstering tack is driven into the end of the circular piece, as pictured. The method of attaching the torpedo-tube to the deck is clearly illustrated in Fig. 104 and no further directions need be given. If the model-builder has a small piece of brass tube on hand suitable for use in this case, it will make a much better appearing tube than the piece of wood illustrated.
A wireless antenna is shown at Fig. 105. This is a fitting that will do much toward improving the appearance of any craft. Very fine copper wire is used for the aerial. The little spreaders are cut to shape from wood, and a tiny hole is punched through them through which the wire is placed. Black beads slipped on the wire serve very well as insulators. The lead-in wire which drops to the wireless cabin is attached to the aerial by winding it around each one of the aerial waves. The aerial should be suspended between the masts of the vessel. A few words should be said about masts in general. If there is one way in which a model-builder can destroy the appearance of a model boat, it is by using badly proportioned masts. The average boy seems inclined to use a mast of too great a diameter, which makes it out of proportion with the rest of the boat. It is better to have a mast too small rather than too large.
The method of producing railing is shown in Fig. 106. The same small brass rod that was used for the davits can be used for the rail stanchions. One end of the stanchions is hammered flat and drilled out. The stanchions are fastened to the deck by first drilling small holes and forcing them into it. Thread or very fine wire is used for the railing. Fine wire is preferred owing to the fact that it will not break so easily under strain.
Fig. 107 shows a good method of producing stairs. It must be remembered that stairs are often used in model-boat construction. First a strip of tin is bent as shown. Then two more strips, which act as side pieces, are cut. One of these strips is soldered to each side of the stairs. Then six stanchions, which can be made from heavy copper wire, are soldered to the side pieces, as shown. The railing can be made from copper wire or black thread.
Fig. 108 shows a small skylight placed on the deck. This is easily made from cigar-box-wood glued together. The holes in the top pieces for the windows are cut with a very sharp knife. It will be necessary to use a little patience in this, to prevent the piece from splitting and to prevent cracks. A piece of celluloid is glued underneath the top pieces before they are finally glued in place.
A small quick-firing deck-gun is shown in Fig. 109. This is a very simple fitting and can be made with very little difficulty. The base of the gun is formed by cutting a thread-spool in half. A piece of small brass tubing is used to form the barrel. A little piece of sheet tin is looped over the back of the gun to represent the breech. A tiny piece of wire is held to the side of the breech with a drop of solder, to represent a handle. The shield of the gun is cut from a piece of tin, as shown. A hole is made in the bottom of this, so that the nail that passes through the barrel of the gun will also pass through this hole and into the spool. The center of the spool should be plugged to hold the nail. After the gun is painted gray or black it will appear very businesslike, considering the small amount of labor spent in producing it.
Anchors are more or less difficult to make (Fig. 110), and unless the builder is endowed with a great amount of patience he will not be able to file them out of solid metal. A dummy anchor can be easily cut out of wood, however, and when painted black it will answer instead of a metal one. The anchor shown at A is a very simple type made out of a solid piece of wood. The one at B, however, is made out of two pieces of wood fastened together with a pin, as shown. The bottom piece of the anchor shown at B should be rather thick to get the proper effect, and the two points should be tapered nicely. The center of the bottom piece should be hollowed out to accommodate the vertical piece.
A common hatch is shown at Fig. 111. This can be made in the form of an open box from cigar-box wood, and glued to the deck. It is not necessary to cut a hole in the deck for this purpose.
A cargo-hoist for use on model freight-boats is shown in Fig. 112. This is a very simple piece of work and will need little description. Several stay-wires should be fastened to the main-mast and held to the deck with small screw-eyes. The boom should be made a trifle smaller in diameter than the mast. The pulleys are dummy, like those on the life-boat. A little hook bent to shape from copper wire is placed on the end of the thread, as shown.
Fig. 113 shows a method of making a whistle and an engine exhaust. The engine exhaust is made of a piece of wood, and the furled top is produced by an eyelet such as those used in shoes. The engine exhaust is always placed immediately back of the last smokestack. The whistle is a simple device made almost entirely of wood. The whistle-cord is of thread attached to the small piece of wire, as shown.
Fig. 114 shows the method of making spray-cloths for the top of the pilot-house. Small brass brads are driven into the top of the pilot-house, and white adhesive tape is placed on the brads, as pictured. Advantage can be taken of the adhesive substance on the tape which holds it in place on the brads.
A rudder is shown in Fig. 115. The rudder-post should be a piece of brass rod so thick that it can be split with a hacksaw. The sheet brass that forms the rudder proper is placed in this split and soldered. In the case of an ornamental boat the rudder can be fixed as shown in Fig. 115. It will be seen that it is quite impossible to keep the rudder in adjustment in this way.
If the rudder is to be kept in a certain adjustment a quadrant is necessary. This is made by using a semicircular piece of heavy sheet brass and filing little notches in it. The lever of the rudder rests in these notches, and by this means the rudder can be held in any one position, so that the boat will either turn in a circle or go straight. Fig. 116 illustrates such an arrangement.
THE DESIGN OF MODEL STEAM-ENGINES
INSTEAD of describing the construction of several model engines of different design, the author thinks it advisable to put the reader in possession of the fundamentals of model steam-engine design and construction. In this way the model engineer will be able to design and construct model steam-engines according to his own ideas and in accordance with the raw materials and miscellaneous parts he may find in his workshop. Unless the young mechanic is in possession of a very well equipped workshop, it is quite impossible to construct a steam-engine according to certain specifications. However, if he has in mind the fundamental principles of steam-engine design, he can go ahead and design his engine, for which he will have no trouble in machining or producing the parts that enter into its construction. By this the author means that the workman can design his engine to meet the materials he has on hand.
Notice Fig. 117. This is a cylinder into which is fitted a piston. If steam is forced into the cylinder the piston will be forced to the opposite end of the cylinder. If some means is then provided so that the steam can escape and the piston come back, another impulse can be given it by admitting more steam, and thus a continuous motion may be produced. This is how the steam-engine works.
Having learned how motion is imparted to the piston by the expansion of steam under pressure, attention is directed to what is known as the "D" slide-valve. This slide-valve permits steam to enter the cylinder and to exhaust at proper intervals. See Fig. 118. Steam enters the steam-chest through the pipe A. The slide-valve is shown at D. When the slide-valve is in the position shown, steam enters the cylinder, and by the time the cylinder has arrived in the position shown by the dotted line C, the slide-valve moves over, closing the passage B. The steam under pressure forces the piston to the opposite end of the cylinder. When the piston reaches the opposite end of the cylinder, steam that has entered through the passage F again forces the piston back to its original position. This is caused by the slide-valve shifting its position, because of the impulse it received at the opposite end of the cylinder. Thus it will be seen that when the piston is at one end of the cylinder the opposite end is exhausting. By carefully studying Fig. 118 the action of the D valve will be understood. The connecting-rod E is connected to the crankshaft and in this way the engine is caused to revolve.
A cylinder similar to that shown in Fig. 118 is called a double-acting cylinder. This is because the steam acts on both sides of the piston. Single-acting cylinders are cylinders in which the steam expands on only one side of the piston. In the single-acting engines the D valve is modified.
The "stroke" of a steam-engine depends upon the length of the cylinder; really, the stroke is the distance travelled by the piston. In model engines it ranges from 3/8 of an inch to 1-1/2 inches. The bore of a cylinder is its internal diameter. The bore is usually a trifle smaller than the stroke. Thus it is common to have a stroke of 7/8 inch and a cylinder-bore of 3/4 inch.
At this juncture the author would caution the more inexperienced young mechanics not to build double-acting engines. The valve mechanism is somewhat intricate and very difficult to regulate. The construction is also much more complicated, and this also holds true of the designing. On the other hand, single-acting engines, while not so powerful for a given size, will do very nicely in driving model boats, and will deliver sufficient power for all ordinary purposes.
Your attention is directed to Fig. 119. This shows a design for a model single-cylinder, single-acting steam-engine. The reader should carefully study each drawing before continuing to digest the following matter. The cylinder L can be made from a piece of tubing. This can be either brass or copper. Aluminum should not be used, owing to the fact that it is difficult to solder and difficult to work with. The piston is made so that it will fit nicely into the cylinder and move up and down without binding. It will be seen that a groove, M, is cut around the piston near the top. String soaked in oil is placed in this groove. This is called packing, and the presence of this packing prevents steam leakage between the piston and the cylinder walls and thereby materially increases the efficiency of the engine.
In this case the connecting-rod R is made in a circular piece. It is attached to the piston by a pin, F. The connecting-rod must be free to revolve upon this pin. The engine shown has a stroke of 7/8 inch. Therefore, the crank-pin K on the crank-disk N must be placed 1/2 of 7/8 or 7/16 inch from the center of the disk N, so that when this disk makes one revolution, the piston will move 7/8 inch in the cycle. Thus it will be seen that the distance of the crank-pin K from the center of the crank disk N will depend entirely upon the stroke of the engine. It may be well to mention here that the worker should always start designing his engine by first determining the bore and stroke. Everything depends upon these two factors. It is also well to mention here that the piston should never travel completely to the top of the cylinder—a small space must always be left for the steam to expand. One eighth of an inch is plenty of space to leave.
It will be noticed that the valve mechanisms on the particular engine shown bear no resemblance to the D valve previously described. The holes G which are bored around the cylinder are the exhaust ports. It will be seen that when the piston is at the end of its downward stroke it uncovers these exhaust ports and permits the steam to escape. The momentum of the flywheel A pushes the piston upward, closing these holes. As these holes are closed the valve H uncovers the entrance I and permits steam to enter from the boiler through J. By the time the piston has reached the upward limit of its stroke a considerable steam pressure has developed on top of the cylinder, and this again forces the piston downward. Thus the same cycle of movement is gone through repeatedly.
The valve on this little engine is extremely simple. It consists of a circular piece of brass drilled out, as shown. A hole (I and J) is drilled transversely through this. The little cylinder shown in the insert at O slides in the larger hole, and when it is at its upper limit it cuts off the steam. At the proper intervals the valve is pulled down by the eccentric C. It will be seen that the moving parts, i.e., the valve and the piston, must be properly timed. That is, the eccentric C must be mounted on the crank-shaft B so that the valve will close and open at proper intervals. When the engine is made, the eccentric can be shifted about by means of a set-screw, Q, until the engine operates satisfactorily. This set-screw is used to hold the eccentric to the crank-shaft. The word eccentric merely means "off center." Thus the eccentric in this case is formed by a little disk of brass with the hole drilled off center. The distances these holes are placed off center will depend entirely upon the motion of the valve. It will be seen that the valve is connected to the eccentric by means of the valve-rod E. The valve-rod, in turn, is held to a circular strap which is placed around the eccentric. A groove should be cut in the surface of the eccentric, so that this strap will not slip off. If the strap is not put on too tightly and the eccentric is free to revolve within it, the valve will be forced up and down as the eccentric revolves.
The crank-shaft B revolves in two bearings, D D. The flywheel is held to the crank-shaft by means of a set-screw S.
Most small engines with a bore under one inch will operate nicely on from 20 to 30 pounds of steam, and this pressure can easily be generated in the boiler that was described in the chapter on model-boat power plants.
A MODEL FLOATING DRY-DOCK
AS many of the readers probably know, a dry-dock is used in assisting disabled vessels. Some dry-docks are permanent, while others are built so that they can be floated or towed to a disabled vessel that is not able to get to a land dry-dock. The land dry-dock operates as follows. It is first filled with water, and the disabled boat is towed in by tugs. After the tugs leave, the gates are closed, and the water in the dry-dock is pumped out, leaving the boat high and dry. Large props are put in place to prevent the boat from tipping.
The dry-dock here described is a model that is towed to a disabled vessel. It is then sunk until it passes under the boat. The sinking is brought about by filling the dry-dock with water. After it has sunk to the proper depth it is passed under the boat to be repaired, the water is pumped out, and the dry-dock rises, lifting the disabled boat with it. Repairs can then be made very easily.
The model here described does not possess all the fittings and additions of the original. However, it is able to rise or sink as required, carrying the machinery necessary to bring about these functions.
A general view of the completed model is shown in Fig. 120. The first part to construct is the framework for the hull. Four pieces of wood will be required for this, and they should be cut to the shape and size shown in Fig. 121. To make this it is best to cut the two side parts first, as indicated by the dotted lines. This done, the bottom piece can be clamped on from behind by means of pieces of lath. These are for the two end pieces. The other two pieces are made in the same way, except that they contain holes for the water to pass through, as shown at B. The wood for these frames, or ribs, should be not less than 1/4 inch thick in order to accommodate the pieces used in the construction of the remainder of the hull.
When the builder has made the four ribs, he should proceed to construct the lower deck, which consists of a single piece of wood nicely planed and finished, measuring 14-1/2 inches long by 8 inches wide and 1/8 inch thick. This piece must be nailed to the bottom of each of the ribs, one at each end, and the other two containing the holes at equal distances apart. Tiny nails, similar to those used on cigar-boxes, will be found very suitable for this work. Some old cigar-boxes may be broken apart to obtain the nails for this purpose. Before nailing on the board it should be marked out to present ordinary deck-boards. The reader is referred back to Chapter 9 which describes this process, using a straight-edge and knife.
When this board is nailed in place, the next requirement will be two pieces for the sides the bottom edges, of which must rest on the top of the deck-board. These boards are the same length as the deck. They should reach to the top of the ribs, and be fastened in the same way as the bottom deck. It is good practice, when doing this, to place a little white lead on the bottom edge before finally driving the nails in place. This will tend to produce a water-tight joint. This done, three pieces of wood 5/8 inch square must be screwed in place, flush with the bottom ends of the ribs, to form a flat keel. They should be firmly fixed since a lead keel is afterward screwed on the bottom of the boat. Attention should now be directed to fitting the two middle decks. These are placed 4 inches from the top and are 4 inches wide. In this space the engine and pumps are placed. Therefore, the top deck is made in the form of a lid, and the outside plate made to draw out. In this way the mechanism below the deck can be made very accessible.
The framework of the dry-dock is now completed, and the builder can proceed to fix on the side plates. These are made from sheet tin with a width of 14-1/2 inches. The length must be sufficient to reach from the top of one side, around the bottom of the hull, to the top of the other side. Having cut the tin to the required size, one side is put in place with small nails, spacing them an equal distance apart.
Before securing the opposite side, the builder must first arrange the inlet-valve. This particular member is constructed as follows. First, obtain an old gas-pipe union which measures about 5/8 inch in diameter and 3/4 inch long. With a hacksaw this is cut off in a sloping direction with an angle to correspond with the slope in the bottom of the dry-dock. When this is done, a lid must be fitted to the top by means of a long rod, as clearly shown in Fig. 122. On the under side of this lid a small piece of sheet rubber should be glued, so that when the lid is screwed down the valve will be made water-tight. The valve must now be soldered to the inside of the hull. It is placed in such a position that it will rest just under the center of one of the upper decks when the controlling rod is upright.
The top end of the rod must contain a thread for about 1 inch, and a round plate made to screw on. This plate should be about 3/4 inch in diameter, and contain three small holes around the edge. These holes are used in fastening the plate to the deck. The top of the rod is fitted with a small crank-handle, which is used in turning the rod in either direction. In this way the valve can be either opened or closed. At the bottom of the rod a small swivel should be provided, as indicated in Fig. 122.
The plate or sheet of tin on this side of the hull can now be permanently fixed in place. When this is done a light hammer should be used around the edges to turn the tin into the wood.
With the plates secured in place, the builder must next fix a flat wood keel along the bottom of the dry-dock. This should be screwed to the inside keel, screws passing through the tin plate. A lead keel is then screwed to the wooden keel, and when this is done the dry-dock can be launched. If the foregoing instructions have been carried out carefully the dry-dock should ride lightly on the water.
As a trial the inlet-valve is now unscrewed and water is permitted to enter the hull. When the water rushes in, the hull will begin to sink. The water should be allowed to enter until the hull sinks to within an inch of the lower or inside deck. The valve should then be closed. The exact position of the water should now be found, and a line drawn all around the hull, which can afterward be painted in.
The engine and boilers must now be constructed and placed on the dry-dock, so that the water that was permitted to enter may be pumped out. As a temporary arrangement, a thin rubber tubing is inserted through a hole in the lower deck and allowed to hang outside the water-level. The siphon can then be formed by simply drawing the water up by suction with the lips. A continuous flow will result, emptying the hull within a short time.
Attention is now directed to the construction of the boiler and pumps. The boiler, which is rectangular in shape, is made of thin sheet copper, and measures 4 inches long by 3 inches wide by 2 inches deep. A hole is made in the top, and a brass or copper tube 6 inches long and about 3/4 inch in diameter is soldered in position, as depicted in Fig. 123. This tube acts as a chimney on the dry-dock, but it is really used for filling the boiler, and the top is supplied with a tightly fitting cork.
The ends of the boiler also act as supports, and they are made 4 inches long. The bottom edge is turned up for about 1/4 inch to enable the boiler to be screwed firmly to the lower deck. The boiler occupies a position at one end of the hull, and should fit easily in between decks. A small spirit-lamp is used to furnish heat, and no description need be given of this particular part of the equipment. Before the boiler is firmly fixed in place a small hole should be made near the top at one end. The feed steam-pipe is inserted in this, and soldered in place.
Two small oscillating cylinders, similar to those made for the engine on the Nancy Lee (Chapter 6), should be made. They should not be more than 3/4 inch in length, with a 3/8-inch bore. If the builder has any old model steam-engines in the shop, he may take the cylinders from them instead of constructing new ones for the dry-dock.
The engine is set up as shown in Fig. 124. The first job is to make the frame or standards, and this is in one piece. Two pieces of brass (A), measuring 5-1/2 inches long by 1/2 inch wide and 1/16 inch in thickness, are cut. Next the builder should mark off 1-1/2 inches from either end, and carefully bend at right angles, after which holes are drilled to accommodate the crank-axle B. Two holes must also be made for screws to enable the machine to be screwed to the deck.
The flywheel should be 1-1/2 inches in diameter, while the bent crank has a throw of 3/16 inch. The steam-cylinder is fixed on the outside of one of the uprights, and the steam-pipe must, of course, be fitted from the inside.
The pump-cylinder is composed of a small piece of brass tube 1 inch long and 3/8 inch in diameter. The plunger is 1/2 inch long, and the diameter is just sufficient to enable it to work freely up and down inside the brass tube. One end is shaped as shown in Fig. 125. This contains a saw cut that enables the pump-rod to be placed between and connected with a pin. The bottom end of the cylinder is now fitted with a brass disk in which a hole is made and a 3/32-inch tube soldered in place. The inside surface of this piece of brass should be countersunk, and the piece is then soldered into the end of the cylinder. Before the plunger is inserted a small lead shot is dropped in, which should be larger than the hole at the bottom of the cylinder, thereby covering it. A hole is drilled in at the side of the cylinder, and a small bent pipe fixed in it. At the top of this pipe a short piece of 3/8-inch brass tube is fixed in place, as indicated. This piece of tubing is closed at both ends. The bottom end is treated like that of the pump-barrel and supplied with a large shot. An outlet-pipe is soldered into the side of the delivery-valve chamber and leads to the side of the hull.
The pump E is fixed at the bottom midway between the engine uprights as indicated in Fig. 124. The suction-pipe passes through a hole and down through the deck nearly to the bottom of the hull. After the engine and boiler are connected, a trial can be made. If the foregoing instructions have been carried out, the engine will run at a good speed and a continuous flow of water will be pumped out of the hull. All parts of the engine and pump should be carefully oiled and water should be poured into the pump in order to prime it before its start.
It is understood that two complete boilers and pump units are made for the model, and one is mounted on each side. If the builder desires to increase the capacity of the pumps and install a more powerful boiler and engine, only one pump will be necessary. Otherwise the water will not be pumped from the hull very rapidly.
When the builder has finished the pump units, he should turn his attention to the remainder of the fittings. Two small cranes are made, and one is placed at each side of the hull. They are made of tin. The cab of each crane measures 2-1/2 inches high by 2 inches long by 1-3/4 inches wide. A small roof is fitted on, and a piece of wood fitted to the bottom to serve as a floor. The jib measures 6 inches long by 3/4 inch at the base, and tapers to 1/2 inch. It has 1/4 inch turned down at each side, thus adding considerable strength. The jib is fitted to the cab by means of a wire passed through the sides, and two guy-ropes are arranged as shown. A small piece is now cut out at the top, and a pulley wheel fixed in position by means of a pin passed through the sides.
The winding-drum can be made of either tin or wood. The axle passes through both sides of the cab, the crank being attached to the outside. Fig. 126 shows the completed crane, which is held to the deck by means of a small bolt and nut. A washer should be placed between the bottom of the crane and the deck, to allow the crane to turn freely with little friction.
A hand-rail, made of fine brass wire, is placed around the deck.
Dummy port-holes are fixed to the sides of the dry-dock for the purpose of lighting up the interior of the engine-room. These are furnished from top rings taken from gas-mantles. Anchor-chains are fixed at each end of the dry-dock. The whole dry-dock is painted with two coats of gray paint and the water-line painted in bright red.
Fig. 127 shows the dry-dock with a model boat in position.
OPERATION OF FLASH STEAM POWER PLANTS FOR MODEL BOATS
THE flash steam method of propelling model power boats of the racing type produces a far greater speed than would otherwise be possible. Flash steam plants are far more complicated than ordinary steam-propelled power plants, and for this reason the author devotes a chapter to their description.
A considerable equipment of tools and not a little mechanical ingenuity are required to produce and assemble a workable flash steam plant. However, such plants have gained great popularity in the past few years, and all of the hydroplane racing craft are propelled with such outfits. These power plants are capable of delivering such a tremendous power that speeds as high as thirty-five miles an hour have been reached by boats measuring 40 inches long.
The illustration, Fig. 128, shows a flash steam plant and its various parts. Each part and its function will be described in this Chapter in detail. The gasolene tank A is used to hold the fuel, which is fed to the gasolene burner C. The gasolene burner operates on the principle of the ordinary gasolene torch. First the tank is filled about three-quarters full with gasolene. An air-pressure is then produced in the tank with a bicycle pump. The pipe leading from the gasolene-tank at the top is coiled around the burner, and the free end of it is bent and provided with a nipple, so that the gasolene vapor will be blown through the center of the helix of the coil formed by the pipe bent around the burner. This is quite clearly shown in the drawing.
The cylinder is merely a piece of stovepipe iron bent to shape and provided with several air-holes at the burner end. To start the burner, the vaporizing coils must first be heated in an auxiliary flame. The flame of an ordinary blow-torch is suitable for this purpose. After the coils have become sufficiently hot the valve at the top of the gasolene-tank is opened, and this causes a stream of gasolene vapor to issue at the nipple. This produces a hot flame at the center of the vaporizing coils, and in this way the coils are kept hot. The purpose of heating these coils is further to vaporize the gasolene as it passes through them on the way to the burner. Once started, the action of the burner is entirely automatic. The vaporizing coils are made of Shelby steel tubing with an internal diameter of 1/8 inch.
It will be seen that the flame from the gasolene-torch is blown through the center of the boiler coils B. Thus, any water passing through these boiler coils is instantly converted into steam. In other words, the water "flashes" into steam. The heat of the blow-torch is so great that most of the boiler coils are maintained at red heat even while the water is passing through them.
Notice the water-tank G. A little scoop, formed by a pipe of small diameter, protrudes through the bottom of the boat, so that the forward motion of the boat will cause water to rise in the tank G. An overflow is also provided, so that, should the water not be sucked out of the tank quickly enough, it will not flood the boat. The overflow pipe hangs off the side of the boat.
The water pump E sucks water from the tank, and pumps it through the check-valve K (this valve permits water to pass in one direction only) into the boiler coils. The boiler coils, being red-hot, cause the water to flash into steam the instant it reaches them. By the time the steam has reached the opposite end of the boiler coils, it is no longer steam, but a hot, dry gas at a terrific pressure. From the boiler coils the steam passes into the steam-chest of the engine, and thence into the cylinder, where it expands, delivering its energy to the piston.
It will be seen that the water-pump E is geared to the engine. Owing to this, it is necessary to start the water circulating through the boiler coils by the hand pump F. This hand pump forces water through the boiler coils just as the power pump does. After the hand pump is started the engine is turned over a few times until it starts. The valve H is then closed, which cuts the starting pump F entirely out of the system, because when the engine starts it also drives the water pump E, and therefore the action becomes entirely automatic.
The relief-cock L is placed in the system to be used if the engine stalls. By opening the relief-cock the pressure in the complete system is immediately relieved. At all other times the relief-cock is closed.
A second pump, I, is also included in the system. This, like the water-pump, is geared to the engine and driven by it. It is the duty of this pump to convey oil from the lubricating tank M into the steam feed-pipe just before it enters the steam-chest. In this way the live superheated steam carries a certain amount of lubricating oil with it in the cylinder.
Owing to the high temperature of the superheated steam, it is impossible to use brass cylinders on the steam-engines employed with flash steam systems. Steel seems to be the only cheap metal that is capable of withstanding the attack of flash steam. Brass is out of the question, since its surface will pit badly after it is in use a short time.
The boiler of a flash steam plant is covered with sheet iron so as to prevent drafts of air from deflecting the flame from the center of the boiler coils. The cover is provided with ventilators, so that the burner will not be smothered. If enough oxygen does not enter the interior of the boiler coils, poor combustion will result, and the gasolene flame will not develop its maximum heat. Upon referring again to the diagram, it will be seen that the exhaust steam pipe from the engine discharges into the stack of the boiler covering. This discharge greatly facilitates the circulation of air through the boiler coils.
After a flash steam plant has been started it will work automatically, providing all the parts are in good running order. Flash steam plants, however, are difficult to get in the proper adjustment, and once adjusted they are easily disturbed by minor causes. Owing to the fact that every square inch of surface in the flash coils is heating surface, the amount of water supplied to the boiler must be exactly what is needed. The heat must also be regulated so that the temperature of the steam will just meet the engine's needs. Many times an increase in heat causes the steam to reach such a temperature that it will burn up the lubricating oil before it reaches the cylinder of the engine. This is liable to cause trouble, because sticking is apt to occur.
Model power boats with speeds as high as thirty-five miles an hour have been made in America. Such high-speed boats must be assembled with infinite care, owing to the fact that the mechanism they carry is more or less erratic in its action, and unless it is well made results cannot be expected.
There are probably few sports more interesting than that of model power-boat racing. The Central Park Model Yacht Club of New York city is one of the most progressive clubs in America, and its members not only have a sail-boat division, but they also have a power-boat division. The members of the power-boat section have races regularly once a week, and the most lively competition is shown. It is indeed amusing to watch these little high-speed boats dash across the pond, their bows high in the air and their little engines snorting frantically. Owing to the difficulty of keeping these small racing boats in a straight line, they are tied to a wire or heavy cord and allowed to race around a pole anchored in the center of the pond, as illustrated in Fig. 129. The top of the pole should be provided with a ball-bearing arranged so that the cord to which the boat is fastened will not wind around the post. In this way the boats are caused to travel in a circle, and as the cord to which they are fastened represents the radius of the circle, the circumference can readily be found by multiplying the radius by 2, which will give the diameter. The diameter is then multiplied by 3.1416 to obtain the circumference. If the boats were permitted to travel wild they would run into the bank, a fatal procedure when they are running at high speed.
Speed boat hulls are usually of the hydroplane or sea-sled type. This type of hull is extremely easy to make. Such a hull is shown in Fig. 130. It will be seen that it has an aluminum bottom. The propeller and propeller strut will be noticed in this illustration.
The drawing for the particular hull shown in Fig. 130 is given in Fig. 131. First the two side pieces are cut out to the shape shown. In this particular instance the over-all length of the sides is 39-1/3 inches. This is called a meter boat, and is built with this length to conform with the English racing rules. Next a bow piece is cut out, and this is produced from solid wood. Only two materials are used in the construction of this hull, aluminum and mahogany. Square mahogany strips are cut out and fastened inside of the side pieces by means of shellac and 3/8-inch brass brads. The bottom of the hull is made of 22-gage sheet aluminum. This is fastened to the square mahogany strips, since the sides of the boat are entirely too thin for this purpose. The method of fastening the strips of aluminum will be made evident by referring to Fig. 132. The aluminum bottom does not run completely over the bow piece, but merely overlaps it sufficiently to be fastened by brass brads, as illustrated in Fig. 135. The single step in the bottom of the boat is fastened by a mahogany strip, through which the stern-tube runs and the water-scoop. The back of the boat is made up of mahogany. A small aluminum hood is bent to shape, and this is fastened to the bow of the boat and prevents the boat from shipping water.
In building a hull of this nature the mechanic should exercise care to see that it is in perfect balance, and that the sides are finished and varnished as smoothly as possible. This will cut down both air and water resistance. The position of the propeller strut and stern-tube will be seen by referring to the drawing of the hull in Fig. 131.
The propeller of a high-speed boat is of a high pitch and generally of the two-blade type. It should be at least 3 inches in diameter and with a pitch of about 10 inches. By this it is meant that the propeller theoretically should advance 10 inches through the water for one revolution. The rudder is generally fastened in one position, in case the boat is not used on a string and pole. It will be found advisable, however, always to run the boat in this way, and in such cases the rudder can be entirely dispensed with.
The boiler of a flash steam plant is extremely simple. Such a boiler is shown in Fig. 133. It consists merely of a coil of copper or Shelby steel tubing with an internal diameter of 1/4 inch. The boiler coils should be wound around a circular form of wood about 2-3/4 inches in diameter. In the case of copper it will not be found very difficult to do this, providing the copper is heated before being wound on the wooden form. If the copper is heated it is advisable to wind the wood with a layer of sheet asbestos before the copper tube is wound on. It is almost necessary to do this winding with a lathe, but if the mechanic does not have access to such a tool he may have to find other means of doing it, or possibly he can take it to a local machine shop and have the work done for a few cents. The boiler coil should be wound about 9 inches long.
A casing of Russian sheet iron is made to slip over the boiler, leaving sufficient space between. Ventilating holes or slots are cut in the cover to permit of a free circulation of air. The boiler covering is also provided with a funnel through which the exhaust gases from the blow-lamp pass.
The blow-lamp used operates on the same principle as the ordinary blow-torch. The details of such a lamp are given in Fig. 134, and a finished torch is shown in Fig. 135. Instead of making the valves necessary for the blow-torch, it is advisable to purchase them, for they are very difficult to make accurately. The valve at the back of the torch regulates the gasolene supply that passes through the nipple. The hole in the nipple should be about twenty thousandths of an inch. Owing to the fact that the copper coil wound about the burner is short, the tube can be filled with molten resin before it is bent. In this way the tube will not kink or lose its shape while being wound. After it is wound it is placed in the fire and the molten resin forced out with a bicycle-pump. Such a blow-torch produces a tremendous heat and throws a hot flame far up into the boiler coils.
BEFORE attempting to construct model sailing yachts the young worker should become thoroughly conversant with the different types of yachts and their fittings. In the following pages the author briefly outlines the general science of yacht-making and sailing.
Sailing yachts are made in four principal types. There is the cutter rig, yawl rig, sloop rig, and the ketch rig. The cutter rig is shown in Fig. 136. It consists of four sails so arranged that the top-sail may be either removed altogether or replaced by sails of smaller area. In all yachts it is necessary to haul the sails up into position by ropes known as halyards. The halyards must be led down to the deck. The model-builder, however, can dispense with much of the gear used on larger boats.
A sloop rig is illustrated in Fig. 137. By studying the drawing the worker will see that the sloop rig differs from the cutter rig only in that she carries a single sail forward of her mast.
The yawl rig (See Fig. 138) is similar to a cutter rig, but has a small sail set up on another mast abaft the mainsail. The sheet is led aft to a spar that projects beyond the counter. The mast upon which the smaller sail is set is known as the mizzenmast. In this rig it will be seen that the main boom must be made considerably shorter than was the case in the cutter rig. This is done so that it will not follow the mizzenmast when it swings from one position to another.
The ketch rig differs greatly from the yawl rig. The mizzenmast always occupies a position forward of the rudder-post. In the yawl the mizzenmast is always stepped aft of the rudder-post. This will be seen by referring to the drawings of the two boats. The ketch rig is illustrated in Fig. 139.
The prettiest rig of all is the schooner; but, owing to the fact that it is difficult to get them to go well to windward unless the hull is perfectly rigged, the author has decided not to deal with this type of boat. When the reader becomes proficient in building and sailing the simpler types described in this book, he may turn his attention to the construction and sailing of more complicated types.
Model Yacht Parts
The submerged portion of a yacht is, as in all other boats, termed the hull. The backbone of the hull is called the keelson. Attached to the keelson is a piece of lead, which is put in place to give the boat stability and power to resist the heeling movement created by the wind-pressure upon the sails. This is known as the keel.
Yachts always have an opening in the deck giving access to the interior of the hull. These openings are known as hatchways. When sailing in rough weather the hatchway is closed by a hatch to prevent the yacht from shipping water.
The extreme forward end of a yacht hull is called the stern, while the portions forward and aft of the midships section are known as the fore and after-body respectively.
In all yachts a portion of the hull extends out over the water. These portions are known as overhangs. The overhang aft is sometimes called the counter-stern. The sides of the hull that rise above the deck are called bulwarks, and the part of the bulwarks that cross the stern is called the taffrail. The taffrail is always pierced with holes to allow water to run off the deck quickly, so that the additional weight will not in any way affect the course of the boat. It is understood that yachts raise great quantities of water upon their decks when traveling in rough sea.
The bowsprit is passed through a ring at the top of the stern, and this ring is termed the gammon iron. Its end is secured in a socket or between a pair of uprights called the bowsprit bits. These are fixed to the deck. Metal bars are fixed a short distance above the deck to take rings attached to the sheets. This is done so that the sails may swing freely from one side of the boat to the other. Metal eyes are screwed into the sides to take the shrouds, and are called chain-plates. The eye in the stern is called the bobstay plate. In the stern-post are two eyes called gudgeons. The rudder is hooked to this by means of two hooks called pintles. The bar or lever that is fixed to the top of the rudder-post is called a tiller.
The parts and fittings of a mast follow: the step, the head, the caps, crosstrees, truck, topmast, boom, and gaff. The part of the gaff that rests on the mast is called the throat; the end of the gaff is called the peak. The jib-boom is a term used only in connection with model yachts. In larger boats the jib-boom is an extension of the bowsprit. The small boom that projects over the stern of a yawl is called the bumpkin. The spar is rather a general term applied to practically all wooden supports of sails. The spar of a lug-sail is called the yard. It is different from a boom or gaff, by reason of its lying against the mast instead of having one end butting on the mast. Anything belonging to the mainmast should be distinguished by the prefix main. Thus, there are the mainsail, the mainboom, main-topsail, etc.
A sail for a model cutter-rigged yacht is shown in Fig. 140. The bowsprit and masts are, when necessary, given support by ropes that are stretched tightly to some point where they can be conveniently anchored to the hull. The following are those largely used on model yachts: topmast stay, bobstay, topmast shrouds, and forestay.
The sails are pulled up and fastened by ropes termed halyards. The halyards are fastened to the upper portions of the sail, and they are named according to the sail to which they are attached. For instance, there is the jib halyard and the foresail halyard. A mainsail carried by a gaff has two halyards, the throat and peak. The movement of the sails is controlled by ropes, called sheets, which take their names from the sails they control. There is a mainsheet, a jibsheet, and a foresheet. The reader should take note of this term and refrain from confusing it with the sails.
Sailing Model Yachts
The sailing of model yachts is a real art, and the author warns the reader that he cannot hope to become a proficient yachtsman by merely digesting the information given in this book. His real knowledge must be earned by experience in handling a model yacht on the water. However, there are few sports that will afford more pleasure than that of sailing model yachts. Being an outdoor sport it is very healthful.
In sailing a model yacht the sails are set, or "trimmed," so that she will continue to sail along the course previously decided upon by the yachtsman. She must do this in as speedy a manner as possible and with as little deviation from her original course as possible. The trim of the sails will depend upon the wind. If the boat is to sail against the wind, that is termed "beating to windward"; with the wind is called "scudding." With the wind sideways it is called "reaching." If the boat is sailed with the wind blowing midway between one of the sides and the stern in such a way that it sweeps from one side of the stern across the deck, this is called "three-quarter sailing" in a "quartering" wind. A model yacht will continue for a great distance on a reach or while scudding; but, on the other hand, it will not be possible for her to sail directly against the wind. If a yachtsman is to make headway against the wind, he must sail his boat as near dead against the wind as it will go.
The cutter type of yacht will move against a wind that is blowing at a very small angle on her bowsprit. As soon as she reaches the limit of her course, the yachtsman turns her bow at a small angle so as to bring the wind on the opposite side of the vessel, and in this way a second course is started. These courses are repeated in a zigzag fashion until the yacht arrives at her destination. This zigzagging, or "tacking," as it is called, is illustrated in Fig. 141. It will be seen that the yacht starts at B, and makes 3 tacks before she arrives at her destination, A. Each time she touches the shore she is "put about" and set upon a new course, or "tack."
It will be understood that tacking is slow work, and a greater distance must be traveled than would be covered by a power-boat, which would be able to go in a straight line. However, with wind-propelled craft this is the only way in which progress can be made against the wind. The left-hand side of a yacht viewed from the stern is called the port side, while the right-hand side is called the starboard side. Thus a yacht sailing with the wind blowing on her port side is on the port tack, while if the wind is blowing on the starboard side she is said to be on the starboard tack. From this the reader will see that Fig. 142 shows an impossible case.
The sails in front of the mast that are placed nearest the stern of the yacht act in such a manner as to turn the bows in the direction of the arrow, as illustrated in Fig. 146, and the sail or sails abaft the mast turn the boat in the direction of the arrow A. The boat thus revolves upon the center of the mast much as a weathercock revolves upon its pivot. If there is more than one mast, all the sails carried abaft the mainmast serve to turn the boat in the direction A. The work of sailing depends greatly upon the skill in balancing these two effects so that the boat will progress in a straight line. To do this the sails are set in a greater or less angle in relation to the center line of the boat. The less the angle that a sail makes with the center line of the boat, the greater is its power to determine in which direction the boat will steer. The more the yachtsman slackens out his jib and foresail, or the smaller he makes these sails, the less their power will be to turn the boat in the direction B. On the other hand, the larger they are and the more tightly they are pulled in, the greater will be their power. When the mainsail and all of the sails abaft the mainsail are slackened out and the smaller they are made, the less their power will be to swing the boat in the direction A.
The influence of a sail upon the speed of a boat also increases with the angle that it makes with the center line of the hull. The more the yachtsman slackens out his sail, the more it will help the boat along. The reader will see that these two conditions interfere with each other, and therefore the trimming of the sails becomes a compromise. It is good for the young yachtsman to remember to sail his boat with the sails as slack as possible, as long as she keeps a good course. He should also remember not to overload her with sails, since the nearer to an upright position she maintains the faster she will go.
It is not possible to depend entirely upon the trim of the sails to keep a model in a given course. This is because the strength of the wind varies so that the sails are in balance one moment and out of balance the next. The sails abaft the mainmast overpower the sails before it when the wind increases. The result of this is that the bow of the boat will be repeatedly turned in the direction A, Fig. 146.
Some form of automatic rudder is therefore generally used to overcome this tendency of the yacht to "luff" in the wind. Fig. 147 shows the course of a yacht reaching from A to B. The dotted lines show the course she should follow. The full line shows the effect of puffs of wind, which repeatedly take her out of her course. Many times she may completely turn around and make a similar course back to the starting-point, as in Fig. 148. There is also the danger of her being taken back when pointing directly against the wind—the wind will force her backward stern first for some distance, as illustrated in Fig. 149. She will do this until she manages to get around on one tack or the other.
The dotted line B illustrates the course in which she would be driven under these conditions. It is not practical to sail a model yacht dead before the wind without an automatic rudder. With the use of an automatic rudder the erratic movements shown in Fig. 148 can be entirely overcome. The action of the rudder is such that every time the boat leans over to luff up into the wind, the weight of the rudder causes it to swing out, and thus prevents her from losing her course. As a different type of rudder is required, according to the course in which the yacht is sailing, the weight should be adjustable if the same rudder is used.
Let us consider scudding before the wind. For scudding the heaviest rudder should be used, or the weight on a loaded tiller should be in its position of maximum power. All the sails abaft the foremast should be slackened out as far as they will go, which will bring the booms almost at right angles with the center line of the boat. If the craft is a cutter or yawl with a light weight, the yachtsman should rig the spinnaker. The head-sails may be left slack or can be tightened. Fig. 150 shows the position of the booms when scudding with a schooner and yawl. The yawl is shown scudding goose winged. The cutter is illustrated with the spinnaker set. The other craft is a two-mast lugger with balanced lugs.
Attention is now directed to "reaching." For this particular work the yachtsman should put on a medium rudder. When using a weighted tiller the weight should be put in a midway position. The head-sails should be pulled in fairly tight and the aft-sails made slack. The yachtsman, however, should not slacken them as for scudding. Fig. 151 shows a schooner reaching. The thick black lines represent the booms of the sails. If the wind is very light a spinnaker-jib may be set or a jib-topsail in light or moderate breezes. In the case of a wind that comes over the stern quarter, as indicated by the arrow A, the next heavier rudder, or its equivalent in weighted tiller, should be put in operation, and the sails slackened out a little more than before. The boat is then said to be free and sailing on the starboard tack. If the wind is coming in the direction B the jib and foresail may require slackening and the aft sails pulled in more than when sailing with the wind in the direction C. A still lighter rudder can be used as the course gets near to beating windward, and the yacht is said to be close-hauled on the starboard tack.
In beating to windward, if a rudder is used at all, it should be as light as possible, just heavy enough to keep the boat steady. However, this is just the condition of sailing when a boat can dispense with a rudder. It depends entirely upon the characteristics of the particular yacht being sailed, and for this the yachtsman must depend upon his own experience. The jib-topsail should not be used in a case like this, and if the wind is fairly strong a smaller jib should be set than that used for reaching. It is advisable to slacken the jib and foresail out and pull the aft-sails in somewhat tightly. Fig. 152 shows a cutter beating to windward on a port tack. In this case she will have to pay out to starboard a bit before her sails fill.
In sailing the weather must be watched very closely, and the amount of sail carried will depend entirely upon the weather conditions. A yacht should never be overloaded with sail. If she has more than she can comfortably carry she will heel over and drag her sails in the water. Not only this, but she will also drift to leeward when beating to windward. When sailing a new boat, her best trim for various points of sailing and force of wind must be found by painstaking experiments. The boat should always be sailed with her sails as slack as she will take them and keep in her course. In this way she will move faster than when the sails are pulled in close.
The model yachtsman should always watch the wind and note whether it shifts its direction or alters its force. The boat is trimmed accordingly when the boat is put about. Easing or tightening the jib or main-sheet slightly will make a very noticeable difference.
By taking down the top-sail or setting a jib-head top-sail in place of a jack yard top-sail, the yacht will be caused to ride easier in puffs of wind. In case she does not point well to windward when beating, the yachtsman should try a smaller jib, or he can slacken the foresail-sheet. If she runs off regularly to leeward on one tack only, while keeping well to windward on the other, she has some defect in construction or a bent keel.
TWO-FOOT SAILING YACHT
THE model yacht described in this Chapter is the design of Mr. W. J. Daniels, of England, and was described by him in "Junior Mechanics." Mr. Daniels is one of the best known and most successful English designers of model yachts, and the one here described can easily be constructed by the average boy:
In order that the reader may realize the obstacles to be surmounted in designing a model yacht that will sail in a straight line to windward, irrespective of the different pressure that the wind may expend on the sails, it must be pointed out that the boat is continuously altering the shape of the submerged part of her hull: therefore, unless the hull is so designed that harmony is retained at every angle to which the pressure of wind on the sails may heel it, the model's path through the water will be, more or less, an arc of a circle. Whether the boat sails toward the wind, or, in other words, in a curve the center of the circle of which is on the same side of the boat as the wind, or in a curve the center of the circle of which is on the opposite or leeward side, will depend upon the formation of the boat.
As these notes are intended to first initiate the reader into the subject of model yacht building and construction, the design supplied is one in which all things, as far as shape is concerned, have been considered.
It is the endeavor of every designer to produce the most powerful boat possible for a given length—that is, one that can hold her sail up in resistance to the wind-pressure best. Of course, the reader will easily realize that breadth and weight of keel will be the main features that will enable the model to achieve this object; but, as these two factors are those that tend to make a design less slender, if pushed to extremes, the designer has to compromise at a point when the excess of beam and buoyancy are detrimental to the speed lines of the hull.
But the question of design pure and simple is a complex one, and we do not intend to weary the reader just now with anything of that kind, so we will now proceed to build the hull. In order that we may correctly interpret the shape shown in the design without being expert woodcarvers, we must use our ingenuity and by mechanical means achieve our object, at the same time saving ourselves a large amount of labor, such as we should have to expend if we made this boat from a solid block of wood.
Now, as regards understanding the drawings: it is essential to remember that a line which in one view is a curve is always a straight line in the other two views. Those lines which are drawn parallel to the water-line are known as water-lines, and it will be seen that the curves shown on the deck plan represent the actual shapes of the hull at the corresponding water-lines above, below, and exactly on the load water-line. In other words, if after the hull is made it were sunk down to these various levels, the shapes of the hole made in the surface of the water would be as shown in the plan.
Therefore, instead of making our boat from a solid block of wood, we will make our block up from several layers, the thickness of each layer being equal to the space between the water-lines; but before gluing these layers together we will cut them out to the exact shape that the boat will be at their various positions.
It will not be necessary to have a separate piece of wood for each layer, as some layers below the actual water-line will be cut from the pieces of wood that have been cut out from the layers above.
In this case, the boat being 24 inches long, the top layer will be the same length and breadth as the boat, and 1 inch in thickness.
Draw down the center of the board a straight line, and other lines square to it, representing the position of the cross-sections as shown in the drawing. You have now to transfer the deck line to this board, and this is done by marking the breadth at the various sections and drawing a curve through the spots, a thin strip of straight-grained wood being used as a rule, the latter being held down by such weights as are available. For the purpose of laying off the water-lines truly, lines spaced at 1-1/2 inches are shown; the first, it will be noticed, is half a section or 3/4 inch from the stem head.
The material required will be a board of pine about 6 feet long, 8 inches wide, and 1 inch finished thickness.
Nearly all wood-yards stock first-quality pine, but it is in planks 3 inches thick. You can no doubt pick up a short length about 4 feet long.
If so, take it to a sawmill and have two boards 1-1/4 inches thick cut and then machine-planed down to a dead inch. Perhaps you can purchase a board that is already cut, and is fully 1 inch thick, to allow for planing.
Prepare one edge of the board straight with a plane, seeing that it is square to the surface.
As a planing-machine always leaves a series of ridges across the board, varying according to the quality of the machine, it is necessary before transferring the lines to the wood to just skim the surface with a nicely sharpened plane, and set so as to just skim the wood.
The lengths required are: A, plank 24 inches long; B, plank 24 inches; C, plank 18-1/2 inches.
The D plank will be cut from the center of B, but will have to be shifted two sections forward.
Having transferred the various shapes from the drawing on to their respective layers, you saw out each carefully with a bow or a keyhole-saw, care being taken not to cut inside the lines. It is better to cut full, and trim down to the lines with a chisel or plane. A good deal of trouble can be saved by the expenditure of a few cents for having them machine-sawed, in which case ask the sawyer to use his finest-toothed saw.
Having cut out layers A, B, C, and D, fresh lines are marked, as shown by the dotted lines in the plan. These indicate the shape of the inside of each layer when the boat is carved out, and save labor.
These may as well be sawed out now as carved out later. It will also facilitate gluing up, as it will allow the superfluous glue to be squeezed out, and also decrease the breadth of the joint.
In order to get these various layers glued together dead true to their positions as indicated in the design, you must choose a section about amidships, say section 11, and with a square draw a line from that section, which is, of course, still showing on the surface of the layer, down the edge on either side, joining up with a line across the opposite face. Also vertical lines at each end of the midships line must be drawn on the wood, great care being taken to get the midships line on the under face of the layers dead opposite each other.
If your outfit contains half a dozen carpenter's hand screws, these can be used; but if not, it will be necessary to purchase from a hardware store eight seven-inch bolts and nuts 3/8 inch in diameter, with one washer for each, and to make up four clamps, as shown in Fig. 156.
You will start by gluing layer C to layer D, blocks being placed between the surface of the layers and the clamps to prevent bruising the wood. These two are then glued to layer B, and when this is thoroughly set they are glued to the layer A. The best glue to use for this job is marine glue, which does not dry too quickly, and so gives plenty of time to see that the layers have not shifted. In every case one clamp should be placed at each extreme end of the shorter layer, so as to insure the ends making contact, the other two being placed equidistant.
While waiting for the glue to set, you can be preparing the four layers (shown below D) for the lead keel pattern. The lines must be cut out, in this case, with a chisel, as it will be noticed that the lower faces must be left wide enough to receive the top face of the layer beneath it.
It will be noticed that the under face of each of these layers extends beyond the top face aft, and allowance must be made for this. On laying off the lines on the fin layers, do not join up with a point each end, but leave about 1/8 inch thickness, as shown on the drawing.
These layers must be drilled through to take the keel-bolts, which are made from two motorcycle spokes, twelve-gage. These should be cut to a length of 5-1/2 or 6 inches. Great care should be taken to insure that the midship lines are exactly vertical over each other when these layers are glued up.
Before gluing these four layers on to the hull proper, they should be held in position by means of the spokes, in which position they can be sawed to shape for the keel pattern. First, with a small plane or sharp chisel cut down roughly, then a rasp and different grades of sandpaper are used, working across the joints.
It will be realized that, if the pattern for the keel were cut off dead on the line indicated on the design, there would be a loss of wood through the saw cut. In order to obviate this, another line 3/16 inch below the proper lead line is drawn, and the saw cut made between these two lines. You will now plane down each face that is left rough by the saw, straight and square to each of these lines. On the top face of the pattern for the lead, glue or tack a piece 3/16 inch thick along the face, and cut down the edges flush.
You will by this means have made up for the amount of wood carried away by the saw. You will no doubt find a difficulty in holding the pieces of wood for planing in the ordinary way, but it is simple enough if you set the plane nicely, grip it in a vise or bench screw upside down, and push the work over the plane's face, instead of vice versa. But be careful of your fingers!
Take the pieces left from the spokes when cutting down to length, and put these in the holes in the keel pattern. These are for cores, and if you take your pattern to a foundry they will cast it for a small amount, with the holes in it.
Shoot the top face of the lead in the manner before described, and fit on. The hull is now ready for carving out. Screw on your bench two pieces of wood about 18 inches in length and 4 inches wide, so that they project over the edge of the bench about 10 inches. These should be about 15 inches apart. Place your hull upside down on them, and fix it by nailing upward into the top layer. After cutting off the corners of the layers roughly with a chisel you use a small plane set fairly fine, and work all over the hull evenly, taking care not to cut below any of the joints. A small gouge will be required to clear the wood from the region of the after fin, a round rasp—sandpaper being wrapped around a small stick—being used for smoothing down afterward.
Templates of the cross-sections should now be made from thick white paper. This is done by pricking through the design to transfer their shape onto the paper. The cross-sections have on this account been produced here actual size. If cross-lines representing the water-lines are drawn, you will have an excellent guide for fitting, as these lines will, of course, come opposite each glued joint.
Try your templates now and again as you work, and do not try to finish one spot, but keep the whole at an even stage, and you will see the hull gradually grow into shape.
The topsides (which is the name given to that part of the vessel's hull above the water-line) are responsible for the boat's appearance when afloat, and until the top sheer is cut off the boat looks very disappointing. The cross-lines being still on the upper layer, draw square lines from them down the topsides and from the drawing mark the points through which the sheer-line runs. The thickness of the deck must be allowed for, and as this will be just over 1/16 inch, the line must be drawn this much below the finished sheer-line. The arch of the transom must be marked, and the hull cut down to the sheer. To avoid the risk of splitting, a number of fine saw cuts are made down each section line and two or three at the transom.
You now proceed to carve out the inside. Pad your bench bearers and rest your hull upon them. A curved wood gouge with a fairly flat edge is the best tool. Get it nicely sharpened, and work all over the inside of hull until it is about 3/16 inch thick, the top edge being left 3/8 inch wide.
Keep holding up to the light until it is showing a blood-red color, and smooth down the gouge marks with coarse sandpaper.
The hole for the stern-tube must now be drilled, and the tube made and fitted. The hole should be 1/4 inch in diameter. First drill a smaller hole, and then with a 1/4-inch rat-tail file slowly open it out, at the same time rubbing a groove down the stern-post. The stern-tube is made from a piece of light-gage brass tube, it being cut away with a piercing saw to leave a strip the length of the stern-post. Drill three holes in the strip at equal distance and large enough to take a 1/4 inch brass screw, No. 0 size. Temporarily screw the tube in position, and from a piece of thin brass make a plate for the inside. An oval hole will have to be made in the plate to enable it to seat flat over the tube. Solder this while in position. Then remove the whole, and replace, after white-leading where wood touches brass.
The deck-beams, three in number and 1/4 inch square in section, must now be fitted. The sheer edge which we left 3/8 inch wide must be recessed to receive the beams, the recess being made with a 1/4-inch chisel.
Before gluing beams in, three coats of good varnish must be applied to the inside of shell.
The deck should now be prepared and fitted. You will require a piece of pine of ample length and breadth, 1/8 inch in thickness, and after planing finely and sand-papering, pieces of the same stuff should be glued on the under face to reinforce it where the bowsprit, keel-plate, hatch rim, and mast will be fitted. Cut these pieces to shape before gluing on.
Before doing the latter, apply a coat of clear size to the upper face of the deck; this will bring up the grain, so paper it down when dry. This process should be repeated three times.
Three coats of varnish should be given to the under side of the deck after the pieces have been glued on, and when dry the deck can be fitted, 3/8-inch veneer pins being used for fixing on, and care being taken to get it true to position. A center line is drawn down the under side of the deck, and marks made to correspond at the stern and transom on the shell.
The planking lines on the deck can be drawn to suit your fancy, India ink and a draftsman's ruling pen being used to do it, afterward applying two coats of carriage varnish.
To paint the hull, white lead and dryers, in the proportion of 5 to 1 by weight respectively, should be dissolved in turpentine, a few drops of linseed oil being mixed to make it work freely. Have this about the consistency of milk, and, after straining, give the hull about eight coats, one every twenty-four hours, rubbing each down when dry with No. 00 sandpaper. Keep the joint representing the load water-line always in sight by penciling over after each coat of paint is dry. When a sufficient body of paint has been applied, the colors can be applied. Enamel is best for this. Stick strips of gummed paper around the hull at the water-line, and paint up to the edge. When the paint is dry the paper can be soaked off, the paper being again applied, but reversed for the other color. If you can use a lining brush the paper is not necessary for the second color.
While the painting is going on, spars, sails, and fittings can be made. As the spars have to be varnished, it is best to make them first. Pine should be used, and after cutting strips of suitable length and diameter, plane them square in section. With the batten draw on the face the amount of taper to be given, and plane down to this line, still keeping the spar square in section. This having been done, the corners are planed off carefully until the spar is octagonal in section, when it is easy to make it perfectly round with sandpaper by rubbing with the paper rolled around the stick. The diameter of our mast is 1/2 inch parallel until the hoist of the fore triangle is reached, tapering from there to 1/4 inch at the masthead or truck. The boom is 1/4 inch at the gooseneck, thickening to 3/8 inch where the main-sheet is attached, down to 1/4 inch at the outboard end. The jib-boom is slightly less than 1/4 inch parallel.
All spars should be treated with clear size and fine sandpaper before varnishing. This will prevent discoloring by the latter, and will also allow the India ink markings to be made, which latter will be a guide for the trimming of the sails.
In order that any yacht, model or otherwise, may be able to perform her best, it is essential that she should have well setting sails. In fact, in a model a badly setting sail will sometimes even be enough to prevent her going to windward at all. By well setting sails we mean sails that are naturally flat and not made so by straining them out on the spars. Light material, such as cambric or light union silk, is best for this purpose, but not a material that has any dressing in it.
This particular sail plan is very easy to mark out. Lay your material out on a table or smooth surface and pin it down with drawing-pins, sufficiently stretching it so as to pull out any creases. The length of the back edge of the mainsail (which is called the leech) is measured off 1-1/4 inches inside the edge of the cloth, and a curve struck as illustrated. The other two sides of the mainsail are then laid off and pencil lines drawn. You will note that allowance must be made for hemming the back edge of the mainsail. If your sewing-machine has a hemmer, find out how wide a hem it makes (the smaller the better), and make allowance accordingly, twice the width of the hem being necessary. Much depends upon the tension at which the machine is set, so be careful that the latter is sufficiently slack so that it does not draw up the material.
The jib is marked out in the same manner, and, as illustrated, the lines representing the positions of the batten sleeves are drawn. The batten sleeves are small pockets into which thin pieces of cane (called battens) are inserted to help the sail to set nicely. Unless the sail is a good cut to begin with, however, the insertion of these battens will never make it right. The sails should now be cut out with a sharp penknife or scissors, care being taken not to pull the cloth, and especially not along the edges that run across the threads. You then hem the backs and also the foot of the jib. The batten sleeves (which should be of white satin ribbon about 3/8 inch in width) should now be sewn on by stitching down along the extreme edge to the line drawn, and then down the other edge, the ends being left open. A strip of narrow tape is sewn across the foot of the jib-sail to take the strain of the pull, the part of the jib contained by the curve of the foot and the tape being known as the bonnet of the jib.
To prevent the edges of the sails (other than those hemmed) being stretched, you bind them with good tape. The tape is first folded and creased by rubbing over an edge. The end of the tape is then turned in. Take a corner of the sail and place it inside the fold of the tape, care being taken to get the raw edge right up against the crease. The needle of the machine should then be lowered through it as near to the edge of the tape as practicable, taking care that it goes through both edges. Keeping a slight pull on the binding, arrange the cloth in it without pulling the edge. Put the foot of the machine down and sew it, afterward raising the foot again and proceeding as before right around the raw edges of the sail, leaving the needle down each time the foot is raised. Do not sew where a batten sleeve passes under the binding, as you will require the former left open to allow the batten to pass into the fold of the binding. The rings for putting up the luffs of the jib- and main-sail are made by winding a piece of thin brass or German silver wire around a steel rod (the spokes used in the keel being suitable for the latter) and sawing down to divide them. A small eyelet should be put in each corner of the sails, and others spaced evenly at about 2-1/2 inches apart along the boom and about 5 inches apart along the mast, for lacing on. An extra row of stitching may be run down the outer edge of the binding to smooth it down.
The simpler the fittings of a model that is required for practical sailing, the better. They should be as light as practical. Aluminum is not advisable for fittings when the boat is to be sailed in salt water.
The bowsprit fittings, which are known as the gammon iron and heel plate (Figs. 157, 158), are made by soldering pieces of brass tube (cut to suitable size and shape) onto pieces of triangular sheet brass, as illustrated. The horses can either be of wire with the ends turned to suitable shape and fitted with one screw, or they can have plates for two screws, in which case the wire is either threaded and screwed into the plate or silver-soldered to it. Silver-soldering is done with a blow-pipe. The flux used is borax made into a thin paste with water. Silver-solder is bought in small sheets, and a few cents' worth will go a long way if used properly. Cut small pieces about 1/8 inch by 1/16 inch, and, after painting the part to be soldered with your paste borax with a very small brush, pick up the solder with the tip of the brush and put it in position. It will then run around the joint when the metal is raised to sufficient heat.
The hatch-rim is made by cutting a strip of thin brass 1/4 inch in width, the length being the circumference of the oval. The two ends are brought together and silver-soldered. Cut out the oval in a piece of very thin brass and fit in your oval strip so that the flat is just in the center of it. This can then be sweated around with an ordinary soldering-iron, the flat being trimmed down afterward with the shears to leave a flange 1/4 inch in width, the latter being drilled to take 1/4 inch No. 0 round-head screws.
The deck fitting for the mast, (Fig. 159) is made in much the same way, a piece of tube being used instead of cutting a strip of brass. To receive the heel of the mast a fitting known as the mast-step must be made and fitted. This, of course, must be done before the deck is put on. The step is made from two pieces of brass, each about 1/32 inch in thickness, 1 inch long and 1/2 inch wide. One is hard-soldered on edge down the center of the other to form something like a T girder. A slot, as illustrated, is cut in the upright piece with a ward file, and holes drilled in the flat for screwing down on the inside of the boat. A ferrule of brass tube is fitted to the heel of the mast, a cut of suitable size being made in it to receive the upright of the step. A hole should be drilled through the heel of the mast at right angles to the slot, and a wire passed through and riveted, the latter being of suitable thickness to be received by the slot in the step.
The rudder-blade (Fig. 162) is made from a piece of sheet brass fitted to a tube, the latter being an easy fit into the stern-tube already fitted. The blade can be soldered onto the tube. The pintle on which the rudder fits and swings is a strip of brass, the width of the after fin, a wire pin being hard-soldered in to fit up into the rudder.
The pintle (Fig. 163) should be fitted before the painting is started.
In the steering gear, instead of a quadrant, as the fitting on the rudder-head of the "Braine" gear is called, you fit an ordinary tiller (Fig. 164) by bending a wire to suit your fancy and soldering it on to a collar made from a piece of tube that will just sleeve on the outside of the rubber-tube, which latter is fixed by drilling a hole right through it and the rudder head, and fitting a tapered pin.