The mast of our boat was a pole 8 feet long, tapering from a diameter 2 inches at the base to 1-1/2 inches at the top.  A step for the mast was cut from a 2 by 4 block 8 inches long.  A 2-inch hole was drilled into the face of this block.  We had no drill large enough to bore this hole, but accomplished the same result by drilling eight 1/2-inch holes inside of a 2-inch circle (Fig. 168), and then used a chisel to cut off the projecting pieces.  The mast step was firmly bolted to the backbone at its thickest part, that is, just four feet from the forward end.  The mast was braced with stay ropes stretched from the top to the forward end of the backbone and to the ends of the crosspiece.  A 9-foot pole, tapering from 1-1/2 inches to 1 inch in diameter, was used for the boom of the mainsail, and for the gaff we used a 6-foot pole of the same diameter.

[Illustration:  Fig. 169.  The Mainsail.]

[Illustration:  Fig. 170.  Jaws of the Boom.]

The dimensions of the mainsail are given in Fig. 169.  For mast hoops we used curtain rings.  Five were attached to the sail along the luff, and one was fastened with a piece of leather to the end of the gaff.  We used a different scheme for holding the boom to the mast.  The forward end of the boom was flattened at the sides and a couple of cheek blocks were bolted on, forming jaws of the shape indicated in Fig. 170.  The jaws were whittled out to fit nicely around the mast, and were kept from slipping off by a piece of rope passed around the mast and threaded through the ends of the cheek blocks.  Half a dozen small pulley blocks were now procured, of the type used on awnings.  A rope called the throat halyard was strung from the throat or forward end of the gaff through a pulley block near the top of the mast, and led down to the backbone, where it was “belayed,” or wrapped around a cleat.  The cleat, which was whittled out of a stick of wood, was made in the form indicated in Fig. 171.  A short length of rope was strung through a pulley block and tied with some slack to the upper end and to the center of the gaff.  This rope is called a “bridle,” and to the pulley block on this “bridle” a rope was attached called the “peak halyard.”  The peak halyard was passed through a pulley block at the top of the mast, and belayed on a cleat at the side of the backbone.  For the main sheet (that is, the rope used for guiding the mainsail) two pulley blocks were fastened to the backbone, one just in front of the seat and the other a few feet further forward, and two more were lashed to the boom, midway between these blocks.  The sheet was fastened near the aft end of the backbone and then strung through the blocks in the order illustrated, the free end of the sheet being brought back to the seat, where a cleat was provided, to which it could be secured when desired.

[Illustration:  Fig. 171.  A Cleat.]

[Illustration:  Fig. 172.  The Jib-sail.]

[Illustration:  Fig. 173.  The Ice Boat Completed.]