THE application of the marine internal-combustion engine to the British ML class of 80-footers and to the American 110-ft. class of submarine chasers, undoubtedly constituted the most important development along this line of automotive work. With a hull form similar to that of an enlarged runabout, driven by a pair of six-cylinder Standard marine engines rated at 220 b.-hp. at 460 r.p.m., the boats of the ML class averaged about 20 knots. A total of 720 boats of this type were built and the class as a whole proved very satisfactory.
In the development of the 110-ft. SC class, the requirement of seaworthiness was made of greater importance than speed. Each boat carried three six-cylinder Standard engines identical with those used in the British boats, driving them at about 17 knots. Although rather uncomfortable, as in the case of any small vessel, the 110-ft. boats proved wonderfully successful in heavy weather; about 450 of this class were built.
The 220-b.-hp. engines have six cylinders of 10-in. bore and 11-in. stroke. They are started by air and are of the direct reversing type. Many unique features are found in their construction. Some idea of the magnitude of the undertaking is given by noting that the total of 700,000 b.-hp. built during a little over three years would be sufficient to drive twenty-five large super-dreadnaughts of the Arkansas class.