At the higher speeds a succession of waves followed the bow wave along the side of the ship, and if the crest of the last of these waves came at about the middle of the length of the after body, the forward pressure on this part of the ship was increased, and there was a con sequent decrease in the total resistance ; but when the speed was so altered that there was a hollow in place of the crest in the position indicated, there was a decided increase in the total resistance. It would therefore appear that increasing a vessel's length by making an addition to the middle body need not necessarily be accompanied by a favourable character of wave-making. The Guinevere is the best example we know of a yacht with a great straight of breadth, although of course she has not parallel sides, such as could strictly be termed so. The inference is that if 20ft. (equal to about 70 tons displacement) were taken out of Guinevere, her resistance, say at speeds of about 9 knots per hour, would be slightly diminished. At the speeds where the resistance due to wave-making would be very sensibly felt, the case would be different, and greater advantage might be gained by a reduction of her length ; but the fact that the sail-carrying power had been considerably reduced by the abstraction of 70 tons displacement would have to be weighed against this.
This leads us to consider an important matter which has a direct influence on the proportions of yachts. Under the present rule * for estimating the builder's price for a yacht, and for classing yachts for competitive sailing, beam is heavily taxed, as already stated ; and the operation of this rule effectually prevents a designer making a large use of beam to obtain great sail-carrying power. Accordingly, as beam can only be used in a restricted way, great employment is made of weight or displacement. A " long body " is given by making the fore-and-aft lines as straight and full as may be considered consistent with the ex pected speed, and the depth and sharpness of the body are only limited by the same considerations ; t but it seems pretty certain that, for any given length and weight of vessel, better results, so far at least as speed is concerned, would be obtained in smooth water with fresh winds if beam were left entirely unrestricted.
With regard to cruising yachts—or yachts built entirely with a view of getting the most possible comfort whilst afloat—it cannot be con tended that the rule of measurement should necessarily operate against beam. In short, it is the builder's interest to make the vessel as broad as possible, as he is paid by the ton, and under this rule beam increases tonnage nearly eight times as fast as length, if the proportion of length to beam is as five to one. But as a matter of fact the person for whom the yacht is to be built knows this condition of the rule as well as the builder ; and as 8ft. of length is of more value for internal accommodation than lft.
of breadth, it is not surprising that owners are willing to put up with as little beam as possible. However, for cruising, a yacht is generally given a greater proportion of beam to length than a racing yacht ; and either a cutter or a yawl has more beam than a schooner. For any given beam a schooner is generally made longer than a cutler, in order that she may have an appropriate fore and aft spread for her canvas ; or, to put the matter differently, say a certain length is given to the hull more than would be given to a cutter of the same beam, then it is concluded that the schooner rig will be the more suitable, as the length of boom, gaff, and bowsprit of the cutter rig may be found inconveniently extended.
The proportion which beam should bear to length is subject to a great variety of opinions (see "Beam " and " Length " in the appendix), but the true reasons for giving a cruising yacht more beam than a racing yacht are these : In the first place initial stability, or resistance to be heeled from an upright position at the commencement of inclination, is directly proportional to the beam, and as it is very desirable for comfort that a cruising yacht should be kept as upright as possible, she is given such a proportion of beam as will ensure her having a fair amount of initial stability. For cruising, nothing can be more uncomfortable and inconvenient than for a yacht, even in moderate breezes, to be always over on her aide ; it will be impossible to walk about her deck, and the discomfort and disorder below are unbearable. In the next place a very narrow racing yacht would have a quantity of lead inside and outside, and this is incompatible with a com fortable cruising yacht ; and a very narrow yacht, unless she has great depth, would make very bad weather of it in a heavy sea ; she would lie down and wallow in the sea, would always have her lee deck full of water, and would be a difficult and dangerous craft to handle. On the other hand, a yacht which has a great proportion of beam to length may be propor tionately deficient in depth of body, and she will then be lively in a sea, and be of inferior speed, excepting, perhaps, in smooth water, or with a quarter wind.
The results of experience indicate that for a cruising yacht the length should be about times the beam, or in other words, the beam should be equal to the length on the load water line multiplied by ; or, say the length is 80ft., then 80 x •225 = 18ft. = beam. For yachts of less length, say of 40ft., the proportion might be increased to .23, but as small yachts have generally more proportionate depth than larger yachts, this ratio need not be exceeded.