Rowboats, canoes, dories and other small craft may be turned temporarily into motor boats by attaching to them a portable detach able motor made for such purpose. These little engines range from one horse power upward, and are provided with one or two cylinders, the the inlet pipes on one side and the exhaust on the other. The crank-shaft is cased in below. At one end is the fly-wheel, the reversing lever at the other. A 12-horse-power engine in a 30-foot boat may drive it 10 miles an hour or more; with 20-horse-power, 16 to 18 miles may be attained. Racers with 30 to 60 horse-power motors make 30 to 35 miles an hour, meaning in each case statute miles. Over considerable distances the speed shown is much less. For instance, in the Philadelphia-Havana 1,200-mile ocean race in 1910 the winner averaged less than eight miles an hour.
The small open boats employ mostly engines with one or two, and occasionally three cylin ders. In these small engines the bore and stroke are about the same. In the larger en gines, the stroke usually exceeds the bore by 20 to 30 per cent. The displacement speed boats commonly employ four-cylinder to eight cylinder engines, while hydroplanes are built with four- to six-cylinder engines, up to 65 horse power or more. The large cruisers com monly install several motors tandem to get the desired horse power. In small boats the usual motor is of the two-cycle type; in the larger boats the four-cycle type is common, but by no means universal. Tice four-cycle motor is more economical of gasoline, and from a me chanical point of view is superior as a machine, hut it is much more complex than the two cycle motor, and is nearly twice the weight— latter type being more dependable. The motor is self-contained, and is simply clamped upon the stern board of the boat. It will drive an ordinary round-bottom rowboat six to seven miles an hour.
The hydroplane boat is of a distinct type, having a flat bottom or hull in the first instance, then a step being introduced in the hull, this being called a biplane hydroplane. This step
construction involved a division in the bottom or hull, so that the forward half was a "step' lower than the aft half, this step being perhaps two inches high. This worked well, and the multiplane or multistep type was introduced and generally followed, as securing the best re sults. In its natural position the first plane of the hull is on the water level, and as the boat gathers speed the bow rises, and the entire boat is more or less lifted out of the water, tending to skim on top instead of to drag through the water, like other boats. But in order to rise upon the surface the speed must be very great; a slow boat will not The highest au thentic record up to 1 Jan. 1918, is that of the Whip-Po'-Will which averaged 69.39 miles per hour for six one-mile spurts on Lake George, 6 Nov. 1917; and made its fastest mile in 51.55 seconds— a rate of 70.15 miles per hour. Other fast records for 1917 were by Miss Detroit II, 61.72 miles per hour; and Miss Minseapolis, 49.27 miles per hour.
Motor boat races are held regularly at Monaco and many European water resorts; also in the United States, on the Hudson, off Marblehead, off Block Island, on the Missis sippi and the Great Lakes. In the 1917 motor boat race from New York to Albany and re turn, a distance of 235 miles, the winner was Luetta with a record of 29 hours, 38 minutes, 26 seconds. In the Miami-to-Palm Beach, Fla., race in 1917, Roves III completed the 70 miles in 1 hour, 47 minutes, elapsed time. Consult Durand, W. F.,