A Guide to Motor Boat Design and Construction - A Collection of Historical Articles Containing Information on the Methods and Equipment of the Boat Builder. Various
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To get the proper slant on the stern, measure from H 4 1/2 inches to L and saw off the triangle LHK. Make the other side board an exact duplicate of the first one, as in Fig. 228. Next set these two boards on edge, like sledge runners (Fig. 230), and let them be 2 feet, 6 inches apart (the boat will be safer if made six inches wider, and its speed will be almost as great), which can be tested by fitting the stern-boards between them before nailing the temporary boards on, which are to hold them in place (Fig. 230). Do not drive the nails home, but leave the heads protruding on all temporary braces, so that they may be easily removed when necessary.
Fig. 228.
Fig. 229.
Fig. 230.—Parts of motor-boat.
Now turn the boat bottom side up and nail the bottom on, as already described in previous chapters (Fig. 232). The bottom-boards are to be so planed upon their edges that they leave V-shaped grooves on the inside of the boat to be calked with candle-wick and putty (Fig. 231). Next make a shaft-log by cutting a board in a triangular piece, as shown in Fig. 233, and nailing two other pieces of board on it, and leaving a space for the shaft-rod, over which is nailed a duplicate of the bottom-board, as shown in Fig. 234. Make the shaft-log of three thicknesses of 1-inch plank. To make it more secure there should be a board nailed on the inside bottom of the boat, as shown in Fig. 235 by the dotted lines.
This board is put there to strengthen the bottom and allow us to cut a slot through for the admission of a shaft (Fig. 236) which is drawn on a scale shown below it. With the engine comes a stuffing box, through which the shaft passes and which prevents the water from coming up through the shaft-hole. The stuffing boxes, which are furnished to fit upon the inside of the boat, are expensive, but one to fit upon the stern of the shaft-log costs but little, and will answer all purposes.
Of course, when attaching the shaft-log to the bottom, it must be in the exact centre of the boat. Find the centre of the boat at the bow and stern, mark the points and snap a chalk-line between them. Now place the shaft-log in position on this line and while holding that there firmly, mark around it with a carpenter’s pencil. Next lay the shaft-log flat on its side with its edge along this line and with your pencil mark on the bottom of the boat the exact place where the shaft-hole must be cut to correspond with the one in the shaft-log. As may be seen by Fig. 236, the shaft runs through at an acute angle; hence the hole must be bored on a slant, or better still a slot cut through the floor long enough to allow for the slant.
Fig. 231.
Details of motor-boat.
The leak, which would naturally occur here is prevented by the stuffing box which is fastened on to the stern-end of the shaft-log where the latter protrudes for the propeller. To set the engine in the boat it is necessary to have an engine-bed. This is made of two pieces of board cut diagonally, upon which the engine rests.
Fig. 237 shows a piece of 2-inch board and a method of sawing it to make the duplicate pieces to form the engine-bed. The dimension of these pieces must be obtained by measuring the width of the engine rest, which is to be installed. The angle, of course, must correspond to the angle of the shaft.
Make your own rudder of any shape that suits your fancy, square or paddle-shaped, of a piece of galvanized iron or of wood, as shown in the diagram; or you can simply fasten the rudder-stem to the transom (stern-board), as is often done on row-boats and sail-boats. If you desire to make your rudder like the one shown here, use two pieces of galvanized pipes for your rudderposts, one of which fits loosely inside of the other. Make the rudder-posts of what is known as 3/8-inch (which means literally a 3/8-inch opening) and for its jacket use a 3/4-inch pipe, or any two kinds of pipe, which will allow one to turn loosely inside the other. The smaller pipe can be bent easily by hand to suit your convenience, after it has been thrust through the larger pipe.
First bend the lower end of the small pipe to fit your proposed rudder, then remove the larger pipe and flatten the lower end of the small one by beating it with the hammer. To bore the screw-holes in the flattened end you will use a small tool for drilling metal. One of these drills, which will fit any carpenter’s brace, can be procured for the cost of a few cents.
Drill holes through the flattened end of your pipe for the reception of your screws, which are to secure it to the rudder. It is now necessary to fasten a block of 2-inch plank securely to the bottom of the boat upon the inside where the rudder-post is to be set. This block might best be secured on with four bolts. A hole is then bored through the block and the bottom of the boat a trifle smaller than the largest piece of pipe; the latter is supposed to have screw threads upon its lower end (Fig. 238) so that it may be screwed into the wood, but before doing so coat the threads with white lead and also the inside of the hole in the block with the same substance.
When the larger pipe is now screwed into the block until its lower end is flushed with the outside bottom of the boat, the white lead will not only make the process easier, but will tend to keep out the moisture and water from the joint.
From the outside thrust the upper end of the small pipe through the hole in the bottom until it protrudes the proper distance above the larger pipe, and with the point of a nail scratch a mark on the surface of the small pipe where it issues from the big one. At this point drill a hole through the small pipe to admit a nail which is to act as a peg to keep the helm from sliding down and jamming in its bearings.
If you choose, a small seat or deck may be inserted in the stern, through which the helm extends and which will help to steady it. The top of the helm, or protruding ends of the small pipe may now be bent over toward the bow, as shown in the diagram, and by holding some hard substance under it, the end may be flattened with a hammer and two holes drilled through the flattened end for the rudder-line, as in Fig. СКАЧАТЬ