Page:Popular Science Monthly Volume 91.djvu/293

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Popular Science Monthly

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���The shape of the stern of the motor-boat is also of vital importance since it affects speed as well as seaworthiness and ability to run with the sea. Different shapes are adapted for different waters

��3^-in. bolts. Most of these reverse gears have three notches, the center one being neutral, so that the engine may be started without turning the propeller in either direction. The other two notches are for full speed ahead or astern. Although some of the gears are provided with two speeds ahead, the majority of motor-boat operators prefer to control the speed of the boat by the speed of the engine and the latter by means of the spark lever on the timer or distributor in about the same manner as the automobile is controlled.

There are numerous steering devices on the market, but those shown at H, I and / are the most popular for motor-boat use. Sketch H shows the common type of steering wheel where the tiller-rope passes around the drum of the wheel so that turning the wheel in either direc- tion neces- sarily moves the rudder. In connecting up a wheel of this kind the turns taken around the drum must be uneven in number; that is, the tiller rope should pass around the drum three or five times and never two or four. Sketch / shows a lever arrangement which is very satisfactory as a side steerer, provided the guard is set low enough to allow of the lever being moved backward or forward far enough to turn the rudder at an angle of about forty-five degrees of the keel in either direction. This type of steerer is never used except on the side of the craft so that one man may handle the engine and the boat. Sketch / shows what is known as the auto steerer, which is a very

���The position the engine takes relative to the boat hull for directing the shaft downward at the stern end of the boat

��popular type for speed craft and the larger cruisers. In this type, the wheel is between the operator's knees, so that his hands rest on it. The shaft of this apparatus projects below the floor boards and has a sprocket wheel on the extreme end, from which passes the open-link chain which the sprocket teeth engage when the wheel is turned in either direction. The first- mentioned type often causes some annoy- ance through the tiller rope slipping on the drum; this trouble may be overcome by using either a small woven-wire cable in place of cordage or a manila line having a woven-wire cord. With the side steerer there is very little trouble except that caused by the con tinual shrinking and stretching of cotton or hemp tiller rope, but even if the line should get slack it is a very easy matter to take the slack out at the eyes at either side of the lever or with a turn-buckle. The last- mentioned type is preferably used in con- necting with a wire cable so that there is never any trouble through having too much play, or slack.

Another piece of apparatus which is a desirable adjunct' to the modern motor- boat is the generator and magneto. These magnetos are known as high and low tension, the former being for ignition pur- poses only, while the latter may be used also for lighting purposes. In order to overcome the objection of the Steam Boat Inspection Service to this method of light- ing, it is advisable to have a storage battery connected into the lighting circuit

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