Boys' Book of Model Boats Part 5

[Ill.u.s.tration: FIG. 74]

[Ill.u.s.tration: FIG. 76]

Fig. 73 will give the reader a very good idea of the appearance of the boat at this stage. It will be seen that the sketch shows the deck broken away so as to render the cross-batten visible, which also shows the fair-lead at _F_, Fig. 73. This is cut from two small pieces of 3/16-inch stuff, glued and pinned in place. The forward deck is completed by the addition of cowl-ventilators, cut from hard wood and screwed in place. The flag-mast is made from a short piece of 1/16-inch wire. The details of the mooring-cleats are shown in Fig. 74. They are fas.h.i.+oned by using a small screw-eye and soldering a short piece of bra.s.s wire through the eye. An oblong metal plate is then cut and a central hole drilled. This plate is soldered to the shank of the screw-eye and the cleat is complete. One of these devices is to be fitted to the fore-deck and two on the main-deck and stern.

[Ill.u.s.tration: FIG. 75]

The rudder and steering gear will be considered next. Fig. 75 shows the stern of the boat with the rudder gear mounted in place. It will be noted that the rudder-blade is merely a piece of sheet bra.s.s cut to shape and soldered into the rudder-post _M_, which is slit to accommodate it. The rudder-post is hung in two screw-eyes on the stern of the boat. A small wheel about 1 inch in diameter, with an edge filed in it, is soldered to the top of the rudder-post. A fine cord or string, well stretched and oiled, is attached to the wheel and led through two screw-eyes on the deck. From this it is led through an opening in the coaming to a drum on the steering column, which is turned by another small wheel similar to that used on the rudder-post, but with a round edge. The steering column is merely a piece of 1/8-inch wire, held in place by two small screw-eyes fixed in the coaming and with a tube-brush soldered on to keep the wire in position. The drum is simply a hard-wood bus.h.i.+ng driven tightly in place.

The power machinery for the _Nancy Lee_ must be considered at this time.

This is really one of the most interesting parts of the construction.

The general appearance of the power plant can be seen by referring to Fig. 77, which is a view of the complete boiler and engine mounted together on the same base. The boiler is shown at _A_ and the safety-valve and filler at _L_. The base or firebox _B_ protects the burner from stray drafts of air, and also supports the boiler.

The lamp or burner consists of a receptacle _C_ for containing the denatured alcohol. The denatured alcohol is inserted through the filler-tube _E_, which is kept closed with a cork. The upright tube _D_ is fitted so that air can go into the receptacle containing the alcohol.

Three burners are necessary to fire the boiler. These are fitted as shown in _F_, and they give sufficient heat to produce steam enough to drive the cylinder _G_. The steam is conducted to the cylinder through the short pipe _K_. The steam-cylinder has the usual piston and rod, which drives the circular crank _H_. This crank is mounted on a crankshaft carried on the metal tube _M_. As will be noticed, the cylinder is of the simple oscillating type mounted on a standard, formed as part of the boiler casing, and stiffened by two angle-plates _L_.

A heavy flywheel, _J_, is now fitted to the inside end of the crankshaft. This wheel should be a lead casting, and as heavy as possible. A heavy flywheel contributes much to the operating efficiency of the engine. The propeller-shaft and crank are shown at _N_ in the insert.

The boiler is made from a strong tin can about 1-3/4 inches in diameter and 4-1/2 inches long. It is cleaned inside and out, and all the seams are double-soldered. The lid is also soldered on the can. This little boiler, although not elaborately made, will be found capable of standing up under considerable steam-pressure, and so no fear need be had of accidents by explosion.

[Ill.u.s.tration: FIG. 83]

[Ill.u.s.tration: FIG. 78]

[Ill.u.s.tration: FIG. 77]

[Ill.u.s.tration: FIG. 79]

[Ill.u.s.tration: FIG. 80]

[Ill.u.s.tration: FIG. 81]

[Ill.u.s.tration: FIG. 82]

A little safety-valve and filler-plug suitable for use on the boiler are shown clearly in Fig. 78. A piece of sheet tin is cut out to the size and shape ill.u.s.trated in Fig. 79 at _A_. The piece is bent up at the dotted lines and the seams are soldered. Two angle-plates, _B_, are then cut and fitted and soldered in place. Next a piece of bra.s.s tube with a 1/8-inch bore and 1 inch long is cut and soldered in place for the bearing of the crankshaft. A lead flywheel 1-1/4 inches in diameter and 1/2 inch thick is then mounted firmly on a piece of straight steel wire 1-3/4 inches long, which acts as a shaft.

The shaft is made to run freely in the crankshaft bearing that was previously soldered in place. The cylinder is shown in section in Fig.

80. If the reader will refer back to the construction of the engine described in Chapter 4 he will readily understand the operation and construction of this particular engine.

A little crank must be cut from 1/16-inch bra.s.s, and soldered to the crankshaft after fitting a wire crank-pin to the outer edge. This crank-pin should be of such a size that the joint on the end of the piston-rod shown at _A_, Fig. 80, turns on it easily. The throw should be only half the stroke of the engine, which is 3/8 of an inch.

The boiler is now fixed in place by bending the lugs _B_, Fig. 79, so that they just support the boiler nicely. They are then soldered in place. Next fit the short steam-pipe _K_ between the boiler and the steam block on the cylinder. The builder should take care to keep the steam-pipe well up to the top of the boiler.

The lamp should be built at this time. The container for the denatured alcohol is made from a well soldered tin box of suitable size. It can also be made by cutting a sheet of tin to the size and shape shown in Fig. 81. The corner joints are soldered and then a tin lid is soldered in place. The builder should not forget to make the filler-tube _E_ and air-tube _D_, as shown in Fig. 77, before soldering the top piece in place. The burners should be made as high as the container, and these should be made from little pieces of tin bent to shape and soldered on to a bottom pipe, as shown in Fig. 77. The builder should also remember to cut the holes through this pipe so that the alcohol can get into the burner-tubes, and also to solder the open end of the bottom or feed tube. Before the wicks are put into the lamps, the container should be tested by filling it with alcohol to see that it is perfectly tight at all joints. If it is not the container should be gone over again with solder to a.s.sure its being leak-proof.

Before operating the engine with steam, it can be tested with a small bicycle pump through the opening for the safety-valve. The engine should turn over briskly at every stroke of the pump, providing it does not come to rest at "dead center." If it does come to rest at "dead center,"

where no air can enter the piston, the crankshaft should be given a little twist and the engine will then start. Before steam is applied it will be well to experiment until the engine runs with the air-pump.

Having made the engine run smoothly with air, steam can be generated in the boiler. The wicks should not be placed too tightly in the burners.

After they are in place the container may be filled with denatured alcohol, and the burners lighted and placed under the boiler. In a very few minutes steam will be up. At the first indication of pressure in the boiler the engine should be given a twist with the fingers until it starts and goes of its own accord. The constructor should remember to keep his engine well lubricated.

The propeller-shaft is merely a piece of steel wire, perfectly straight and fitted with a crank _A_, Fig. 82. This crank is similar to the one fitted to the engine, but with a small slot cut out for the crank-pin to fit into. This is done so that, as the crank-pin on the engine turns around, it also turns a slotted crank on the propeller-shaft.

A short piece of tube, _C_, is now fitted to a flat bra.s.s plate, _D_.

The plate is mounted at an angle to the tube, so that when it is in place on the stern of the boat the propeller-shaft will be in line with the crankshaft of the engine.

A clearance hole is now drilled through the hull, so that the propeller-shaft can be put in place. Solder the tube to the plate, and punch four small holes in the plate, so that it can be screwed firmly to the hull. Solder a short piece of tube, as shown at _B_, Fig. 82, to keep the propeller-shaft in position.

The propeller must now be made. This is easily done by cutting out a disk of bra.s.s 1-1/2 inches in diameter, as shown in Fig. 83. The shaded portions of the bra.s.s disk are cut away. The blades are bent to shape, care being taken to see that they are all alike. This done, the propeller is soldered to the propeller-shaft.

The only part of the job that remains is to screw the boiler in place under the fore-deck of the boat. This done, the _Nancy Lee_ is ready for her trial. The fore-deck should be made removable by fitting it with pins or screws with the heads cut off, so that the deck only needs pus.h.i.+ng into place. This little boat should be capable of attaining a speed of from four to five miles an hour if it is made carefully and according to the directions outlined in this Chapter.

CHAPTER VII

AN ELECTRICALLY DRIVEN LAKE FREIGHTER

A PROTOTYPE of the model lake freighter described in this Chapter will probably be familiar to many readers. It is a type of boat used on the Great Lakes, and, owing to its peculiarity of design, it lends itself very well to construction in model form.

The lines of the boat may be seen very clearly in Fig. 84.

The hull of the model freighter measures four feet over all, and the beam at the water-line is 8 inches. The extreme draft will be in the neighborhood of 5 inches. This model, when completed, will be capable of carrying considerable weight; in fact, it is able to accommodate thirty-five pounds in weight when used in fresh water. This will give the builder an opportunity to install a very substantial power equipment with little regard for weight.

[Ill.u.s.tration: FIG. 84]

[Ill.u.s.tration: FIG. 85]

The hull is made according to the built-up principle, and the constructor will have to cut his templates before attempting the shaping of the hull. Owing to the depth of the model, it will be necessary to use about ten planks. The plank that is used to form the bottom of the boat is not gouged out. Every other plank is gouged out with a saw and chisel.

The bottom plank is shaped with a knife to conform to the lines of the boat. In building up the hull with the planks, they should first be smeared with glue, and when put in place a few bra.s.s brads should be driven in. As mentioned in an earlier part of this book, iron nails should not be used in work of this nature, owing to the fact that they will rust and cause trouble. The bra.s.s brads are placed about one inch apart the entire length of the boards. The hull is finished with a plane and sandpaper, and after it has been brought to shape in this way and finished, a coat of paint is applied. Black with dark red tr.i.m.m.i.n.gs makes a very good combination for a boat of this type.

The deck is made from a piece of 1/4-inch pine board. Seven hatches are added to the deck. Six of these hatches can be made by merely gluing a square piece of 1/4-inch wood to the deck. The seventh hatch should be made with a hole cut in the deck, so that access can be had to the power motor.

The deck-house, wheel-house, and chart-house, as well as the bridge, should be constructed of tin, which may be salvaged from clean tin cans. The bridge is provided with spray-cloths made from white adhesive tape, as outlined in Chapter 9. The port-holes in the deck-house and hull are made by little pieces of bra.s.s forced in place over a small piece of mica. The life-boats, which are carried on top of the engine-house, are whittled out of a solid piece of wood and painted white. Life-boats are always painted white, regardless of the color of the boat upon which they are used. The life-boats are held by means of string and small dummy pulleys to davits made of heavy stovepipe wire. A rub-streak made of a piece of 1/4-inch square pine is tacked to each side of the hull just below the sheer-line. The rub-streak should be tacked in place with nails such as those used on cigar-boxes.

The funnel measures 1 inch in diameter by 4 inches long. A small exhaust steam pipe, which can be made from a piece of bra.s.s tubing, is mounted directly aft of the funnel. The forward deck fittings consist mainly of a steering-boom, two bollards, two fair-heads, and four life-buoys mounted on the bridge. The main-deck is equipped with six bollards and two covered ventilators, each 1/2 inch in diameter. The foremast is properly stayed in the deck, and should be fitted with rat-lines. The rat-lines can be made with black thread and finished with varnish, which when dry will tend to hold the threads in shape.

The rudder is cut from a piece of sheet bra.s.s to the shape shown, and fitted with a quadrant. The engine cabin can be made from cigar-box wood. The windows and doors can either be painted in place, or the windows can be cut and backed up with sheet celluloid. A good subst.i.tute for painted doors will be found in small pieces of tin painted a different color from the cabin. The same procedure may be followed in fitting the windows and doors to the forward cabin.

We are now ready to consider the power plant. Owing to the large displacement of the boat, it will carry a fairly heavy storage battery.

The electric motor and storage battery are mounted in the manner shown in Fig. 85, which will also give the reader an idea of the appearance of the finished model. As the drawing indicates, it will not be necessary to tilt the motor to any great degree in order to bring the propeller to the proper depth. This is because of the depth of the boat. Instead of a string or belt to connect the motor with the propeller, the shaft of the motor is taken out and replaced by a longer steel rod that will serve both as a motor-shaft and a propeller-shaft. The propeller-shaft extends from the motor through the stern-tube. The propeller used for this model is a three-blade affair, 3 inches in diameter. It must be of this size in order to propel a boat of these dimensions at a consistent speed.

Care must be taken in mounting the motor in this way. If it is not mounted directly in line with the stern-tube the propeller-shaft will have a tendency to bind. However, with a little care no trouble should be experienced from this source. The storage battery used should be of the four-volt forty-ampere hour variety. This boat will be capable of carrying such a battery and this weight should just bring the craft down to her load water-line. The whole deck is made removable, so that the storage battery can be taken in and out at times when it is necessary to recharge it. A battery of this capacity, however, will drive a small motor similar to the type used on the boat for some time.