A GREAT many arbitrary and empirical rules have been from time to time proposed for the placing of masts in yachts, and for regulating their lengths; but, as there appears to have been an inability to base these rules upon the actual stability of a vessel, they are little better than clever guesswork, and might very well prove fallacious ; in fact, a yacht is generally sparred upon what may be termed a principle of comparison. The builder, according to his judgment and experience (which generally lead him to a right, but occasionally to a wrong, result), fixes upon the lengths of the spars without any reference to rules whatever, as he is conscious that the rules, although mysteriously contrived, might lead him astray. The result of the chance system is that the masts very frequently have to be reduced, and not unfrequently have to be increased in length.
No doubt masts affect the stability of a vessel to an enormous extent, and we find in Seabelle that 30 per cent. of her ballast goes to counteract the leverage of her masts alone. A cutter is better off in this respect, as she has only one mast ; but even in a cutter as much as 20 per cent. of the ballast was found to be required to balance the moment of the mast. As masts so largely affect the stability of a vessel, it will perhaps be conceded that a little more care and trouble should be taken in deciding upon their lengths. The position of a vessel's centre of gravity can be appropriately calculated before she is built, and the exact influence the mast will have on that centre will form a large item in the calculation. The objections which we have heard urged against making these calculations are, firstly, that they are very troublesome ; and secondly, that in the hands of an incompetent person they might be as misleading as any empirical rule. The obvious
reply to these objections is, that, troublesome as the calculations may be to those who ordinarily construct yachts, plenty of men can be found who would undertake them ; and to the second objection we would reply by the question, Why should such calculations be placed in the hands of incom petent persons ? But a naval architect would not be content with calcula tions, but would test the stability of a vessel he had designed, unmasted, when afloat. After these experiments had been conclusively made, the effect of a certain length and weight of mast upon the stability could be easily calculated. The sail area would next be determined by the stability of the vessel thus masted, as explained in Chapter V. It might be found that the figure and area of the sails allowed of the masts being reduced ; and there would be this certainty, that, whatever was wrong with the vessel, she was neither over-sparred nor over-canvased. It certainly does seem incredible that, when there is a certain way of proceeding, some yacht constructors should persist in deciding on the length of spars by " rale of thumb," and then giving the length of those spars to the sail maker, who gets as much canvas upon them as he con veniently can.
One of the so-called " rules " referred to is to make the length of the lower masts proportional to the beam ; and, although this rule might easily be misleading, yet it is as much to be relied upon as some of the others, which are a little more complicated.