The finished Sharpie hull without its driving batteries or motor should weigh about 1 pound 3 ounces. The hull being finished, let us consider the electric propelling equipment.
A 1/8-inch cold-rolled steel driving or propeller-shaft is used. The shaft is 13 inches long and a gear-wheel 1 inch in diameter is fixed to one end of this shaft. This gear-wheel meshes with a brass pinion on the motor-shaft. This forms a 31/2 to 1 reduction gear, which produces a greatly increased speed of the boat. The other end of the propeller-shaft rests in the skeg bearing. In this present case this consists of a tube about 1/2 inch long, which is made for a revolving fit on the propeller-shaft and supported by a sheet-metal bracket. This is shown in [Fig. 63] . The end of the propeller also revolves adjacent to the bearing in the skeg.
GETTING READY FOR A TRIP
Heating the blow-torch to a point where it will burn automatically
The propeller is a three-blade affair with a diameter of 21/4 inches. It is attached to the propeller-shaft with a set-screw. The motor is a very simple type obtainable in the open market. It is similar to one shown in [Fig. 41]. As before mentioned, either dry or storage batteries may be used as a source of current. The writer strongly advises the use of storage batteries if possible. The initial cost of these batteries is greater than that for dry batteries; but, on the other hand, the small storage battery can be charged repeatedly and will outlast many dry batteries. If the boat is used much the storage battery will probably be the more economical of the two.
The steering gear of the boat is very simple. The rudder works in a bearing that is screwed to the stern piece. The end of the rudder-shaft is tapped, and a brass screw is used to clamp it in position after setting it with the fingers. The rudder-shaft is a 3/4-inch brass rod. The lower end of this rod is slit with a hacksaw and the rudder is placed in this. Solder is then flowed along the joint.
ALL READY TO GO!
A little boat with steam up, ready for a trip when her owner releases her