Boys' Book of Model Boats

by Raymond F. Yates

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 14¹/₂ 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.