THE AMERICAN ICE YACHT give the sizes of the material, such as used in the construction of the Haze.* The keel, or centre timber, is 24ft. 6in. long, 3in. wide, and 9in. deep (an ordinary " deal "). The side frames are 2iin. thick and 4in. deep.
At the mast a timber, lft. wide, by Sin. deep and 7ft. 6in. long, is fitted on top across the side frames. Underneath the mast timber is the • The engraving is copied from the Scientific American.
" runner " plank, of lft. width, 8in. depth, and about 16ft. loig, the side frames, mast plank, and " runner " plank being all bolted together. Sometimes the side framing is continued forward of the mast timber round to the bowsprit, and thus makes the construction look more boat-like.
The after part of the frame is bottom-planked with inch boards to form the deck.
The "runners " are three in number, one fixed to either end of the runner plank (which crosses the keel at right angles), and the third is fitted aft to the keel timber and rudder post, and is used as a rudder, the pintles being " upside down." This rudder-runner is usually somewhat smaller than the other two, and is fitted with a tiller.
The runners are securely fitted, in a line parallel with the keel, to the ends of the runner plank. They are 6in. deep, 2in. thick, and 2ft. 6in. or 3ft. long. Each runner is shod with steel, and rounded up at the fore end. The shoe is solid, and is llin. deep. One inch of this depth is ground to an angle of 90° V ; the remaining sin. forms the upper part of the shod, and is square with the top, which is 2in. wide. The steel is " tapped" on the upper side about an inch deep. Into these taps fin. bolts are screwed, and are long enough to pass through the runner and runner plank; their heads are then secured with counter-sunk nuts before the runner is fitted to the " runner plank."* As a rule, nothing but the two sails are carried, and the ice yachts of Toronto have but one lateen sail. These lateen sails are similar to the sail described on page 296, and reproduced in Fig. 117. The dimensions of the spars of the Haze are as follows : The ice boats are usually of about the dimensions given; but one, the Icicle, owned by Mr. J. A. Roosevelt, has a framework 32ft. long, is 26ft. between the runners, and the runners are 7ft. bin. These appear to be extreme dimensions. An ice boat built for a gentleman in the North of England in 1879 was 12ft. long, and the runner plank was about 7ft. long, the sizes of the timber being proportionately small. The weight, however, is of use when sailing with a beam wind, to keep the boat from excessive heeling, it being a not uncommon circumstance for the weather runner to be lifted four or five feet off the ice; and in such an event the yacht is lulled sharp up.
The favourite points of sailing are with the wind a point or so before the beam, right abeam, or a point abaft the beam. With such a wind,
a straight course over perfectly smooth ice, free from hummocks and cracks, and a gale of wind, it is claimed that these yachts can and do travel at the rate of sixty or more miles an hour. Every winter we see numerous records of such time made, and they are apparently well authenti cated ; at any rate, it seems incredible that, year after year, American gentlemen should enter into a conspiracy to deliberately publish false times. There is not the shadow of a reason for believing that the time given for making a mile (a statute mile is understood) is persistently exaggerated.* An elucidation of the phenomenon of a vessel sailing faster than the wind has frequently been attempted, bat, so far as we know, with no clear conception of the mechanical principles involved. In the first place, it must be distinctly understood that a boat's speed before a wind which blows with a constant velocity cannot equal the speed of the wind ; under different conditions it is conceivable, and in accordance with mechanical principles, that the speed of a boat may equal, and greatly exceed, that of the wind. If the boat were before a wind which is travelling at the rate of 30 sea miles an hour, the direct impulse of the wind on the sails, if fixtures, would be equal to 61b. per square foot. But the sails are not fixtures, and move before, or away from, the wind ; the pressure is thereby gradually diminished until it is balanced by the resistance met with by the boat on the ice. As the resistance of an ice boat is very small, a high speed—nearly equal to that of the wind—is reached before the resistance and the wind pressure become uniform. Thus, say the velocity of the wind were 30 miles an hour, and the speed of the boat 20 miles an hour, the resultant pressure of the wind would be only of that due to a wind speed of 10 miles, or about Vb. per square foot (see page 19). But if the wind makes a more or less acute angle with the line of advance, the conditions are entirely altered ; the pressure of the wind does not diminish with the advance of the boat, and its effective impulse is determinable on mechanical principles, which will admit as possible a speed of the boat much greater than the actual speed of the wind. However, it is scarcely possible that any water-borne boat propelled by sails could ever be made to exceed the speed of the wind which impelled it, on account of the enormous growth of the resistance due to wave-making ; but " ice boats " may be regarded as having almost no head-resistance ; the slightest force will give them motion, and keep them in motion. The only friction is from the lee runner, as when sailing the weather runner seldom touches the ice, and the lee runner. cutting into the ice, prevents excessive leeway.