)
Fig. 74, details A, B and C, shows the three steps required to make the mastheads. The taper extends downward to the top edge of the trestletrees, and the squared sections below this point have vertical sides.
Next the cheeks are fitted. Those for the sides of the masts are made as in Fig. 71. They can be made with a simple slot for a sheave hole, or they may be slightly thicker to provide a wider slot, into which a very thin sheave pulley can be fitted. Cheeks on the forward and after sides are thin wooden strips glued to the masts between the side cheeks; their thickness must not exceed the diameter of the round mast section below. Note detail C, Fig. 74.
The sizes of trestletrees (fore and aft) and crosstrees (athwartships) are given with the respective masts to which they are attached. Their lower edges are tapered from about half the depth to one-quarter or their lengths from the ends inward. Those for the lower and topmasts have the crosstrees half-lapped into their trestletrees; topgallant and royal crosstrees are thinner in proportion and rest in notches filed into their trestletrees to receive them. See Fig. 72. Be sure that the center line of the trestletrees is flush with the forward side of the mast, to provide a square opening for the heel (lower end) of the mast above. This should be a loose fit, as certain rigging lines must also pass through the same opening as the upper mast. The top surfaces of trestle and crosstrees are flush, or nearly so, to seat the tops which rest upon them. The upper mast trestle and crosstrees are glued in place; the larger, lower trees should also be doweled with bamboo splints to make them more secure. No cheeks are required on the upper-masts, their squared sections being satisfactory for attachment of the trestletrees. We can dispose of the mizzenmast by noting its exceptions to the first two. Its masthead is simply "padded out" with rectangular wooden strips on all four sides, similar to the forward cheek shown at C, Fig. 74.
Copyright, © 1933, by Popular Mechanics Company
