Page:Popular Science Monthly Volume 88.djvu/169

 How to Build an Ice-Boat

��THE ice-boat described is fast for its size, and can be built at a small cost. It has a sail area of about 70 sq. ft. — enough to carry two people. Good lum- ber should be used, such as bass wood or white pine, and the weight should be kept as low as possible.

The sail is of the "balanced" type. The dimensions are : Boom, or bottom, 10'; gaff, or top, 6'; leach, or back, 12'; and luff, or front, 7'. This sail can be

���Fig. I. The completed ice-boat, showing details of the sail

drawn tight by means of the rope and pulley on the boom as shown is Fig. 3. The flatter a sail hangs, the closer the boat will sail into the wind, for which reason two bamboo poles are put across the sail as shown in Fig. 1. A set of

���Fig.

��2. Showing construction of the runner plank

��reef points should be fastened to the lower bamboo pole so the sail area can be decreased in case of a strong wind.

In making the sail, first chalk its out- line on the floor, cut and sew the strips as shown in Fig. 1. The outer edge should be turned over and a cord sewn in. The top of the sail is not straight but is cut with a slight curve. Lace the sail to the poles with a strong cord.

The mast is 14' high. Care should be taken to select straight-grained wood for the mast. At one-fourth of the distance from the top, the mast should be 3" in diameter and taper to 23/2" at top and bottom. The bottom should rest on a hardwood block with a 2^" hole drilled into it. Drill this hole lyi" deep and fasten the block securely to the bowsprit I3/2' in front of the center of the runner plank.

The mast is held in place by three wire stays. On the two side stays, turn- buckles should he used to tighten the wires. Fasten a 3V2" ring to the boom with rawhide to hold the boom in place on the mast.

Tie the top ring to the end of the rope, with which the sail is hoisted and thread the rope through the pulley on the center of the gaff. Fig. 3. A strong rope should be fastened as shown in Fig. 3. Do not make the sail poles until the sail is completed, and then make them 6" or 8'' longer than the sail so stretching can be taken up. For drawing the sail in and out, fasten the rope and pulleys as shown in Fig. 1.

The runners and runner guides are made of oak. Cut runners as shown in Fig. 4, and fit iron shoes to them. For runner shoes use ^4" square iron rod and flatten both ends so that holes can be drilled for bolts, to fasten to runners.

���Mast Rigging

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