The Boat Sailer's Manual: A Complete Treatise on the Management of Sailing ... by Edward Francis Qualtrough

Author:Edward Francis Qualtrough
Language: eng
Format: epub
Publisher: C. Scribner's sons
Published: 1896-03-25T05:00:00+00:00

Fig. 89.

Fig. 9a

such as the man's body, are coming into the vertical, in which is the centre of buoyancy, and that of the spars and sails is shifting out to leeward. This is rapidly shortening the righting lever, and therefore the canoe is nearing the capsizing point, and at forty-five degrees this will be reached and then an upset must follow.

But before this point is reached, the man*s balancing power, aided by that of ballast trimmed to windward, comes into play, and the craft receives a new lease of stability, as in Fig. 90 the only danger then remaining is that of the lee well-coaming get-

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ting under water, or of the weights Hnddenly slipping to leeward.

In the Figures the positions of the centres are exaggerated, for the sake of clearness : h represents the centre of buoyancy (through which a force acts upward at right angles to the water's surface); g is the mean centre of gravity of all the weights, such as ballast, crew, spars, sails, centreboard, and hull; a force acts downward, vertically through g.

Each of these two forces is exactly equal to the weight of the canoe and its contents.

The horizontal distance between the verticals of g and b is the <' righting couple," and so long as g has any horizonttd distance to windward of 6, the canoe has stability; but in Fig. 89, g and h have been brought into the same vertical line, the meta-centre has been made to coincide with the centre of gravity, consequently the vessel is in equilibrium, and a touch either way will settle the question of capsize or right.

The centre of gravity of the separate parts are represented individually in the Figures, a being that of the man, d of the ballast, c of the centreboard, and 8 that of the spars and top-hamper.

The stability of a canoe in which the ballast is not shifted and the man's position not altered would rapidly decline after a heel of about twenty-five degrees, and vanish entirely at about forty-five degrees; but if the man and ballast both shift up to windward, the canoe will be safe, even though a puff should suddenly force her over to forty-five degrees.

Suppose a canoe to be sailing, and heeled oyer to an angle of about twenty degrees, and working short tacks where there is no time to trim ballast over, and where the wind is coming in sudden pufiGs: it will often be found necessary to do a multitude of things at the same moment; such as to sit over to windward, to luff sharply before steerage-way has been lost in consequence of the sails banging about, to ease off the head-sheet and flatten in the mizzen, and perhaps to lift the centreboard for shoal water; and then have to go about suddenly, and perform much

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of the' same thing on the other tack, with perhapd the addition of taking in or shaking out a reef or two.

The necessity of performing the

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