Page:Popular Science Monthly Volume 91.djvu/291

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Practical Motor-Boating

II. — The proper location of the power plant and mechanical attachments, and their care and operation

��By George M. Petersen

���THE amateur boatman should thor- oughly understand the names and location of the various parts of his craft, in order to take good care of it. The principal ones are as follows: stem, keel, stern-post, dead wood, shaft-log, keel- son, bilge keelson, deck beams, stringers, knee, shear-brake, ribs, bulkheads and car- lines. The planking of the hull is really the skin or shell. It covers the ribs and frame of the boat and may be applied in several different ways. The edge nail construction is probably the most durable for a boat which is subject to severe pounding through seas or heavy engine vibration, as the planks are narrow and are secured through both the edge and the face.

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. For instance, the V-shaped stern shown at points A and B on page 277 may give the longest water line on a given overall length as well as the most protection to the rudder, but it is not a good design for backing or running with an overtaking sea. The "square transom" and the "rounded tran- som" are fairly satisfactory types, al- though the rounded is more expensive to construct. A "compromise stern," D, is seaworthy and dry when running before a storm, but it is never used on a craft where the maximum of accommodation is desired because of the large amount of

��deck-room which is sacrificed to its use. The old style "fan-tail" is shown at E. This is now almost obsolete, for the reason that it is almost impossible to back a small boat against a heavy sea because of the resistance offered to the hull by the waves. This type is inclined to be un- wieldly when running with a sea, as the waves will lift the stern. A type of stern which is still popular is shown in the illustration above. It is known as the "torpedo." This type is adapted to shallow waters where a minimum draft is desired, but has a tendency to squat when the boat is under way, thereby greatly decreasing her speed. It is a good "heavy weather" type, however.

Strictly speaking, the power plant con- sists of the engine only, but it is customary among small motor-boat operators to in- clude everything that is connected with the actual operation of the craft. For instance, the engine classification includes the following: the crank-case, or base of the engine; the cylinder, including the water jacket, or top of the engine; the crank-shaft upon which is mounted the fly- wheel at the forward end while the shaft connects with the rear end ; the connecting rod which connects the piston with the crank-shaft, being attached to the form by means of a "wrist pin"; the carburetor, by means of which the proper amount of air is admitted with the gasoline to the compression chamber; the spark coil and battery which generate the spark which is

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