'Dunraven.'
An attempt will be made to treat the subject as simply as possible, so that anyone who knows a little arithmetic may follow it.
The following 'hieroglyphics' will be used:—
| B. | Beam |
| D. | Draught |
| F. | Freeboard |
| G. | Girth |
| L. | Length |
| L.O.A. | Length over all |
| L.O.M. | Length between official marks |
| L.W.L. | Length on W.L. |
| M. | Area of immersed mid-section |
| M.S. | Mid section |
| R. | Rating, whether Y.R.A., or corrected length, or other |
| S. | Sail area |
| T. | Tonnage |
| U.Y.F. | Union des Yachts Français |
| W. | Weight of yacht complete in English tons dead weight same as her displacement |
| W.L. | Water level |
| Y.R.A. | Yacht Racing Association |
If the subject of rating were treated historically, it would be necessary to begin with the old tonnage rules; but we live in the present, and the more important of the existing rules will therefore be examined first. The old tonnage rules will more conveniently be described at the end of the chapter, with existing tonnage rules.
England and America have used rating rules for some years, and France determined to do the same in October 1892.
The efficiency of a sailing yacht can be calculated very similarly to that of a steam yacht, the sails being the motor in one, the engines in the other. But we know that the efficiency of a steamer should vary directly as her indicated horse-power, and inversely as her displacement. The same idea should apply to sailing yachts. It is, in fact, almost impossible to rate a sailing yacht satisfactorily without taking into account both her sail-area and her displacement—or something very closely allied with the latter.
A length and sail-area rule proposed by Mr. Dixon Kemp in 1880 was adopted in 1883 for second-class racing, and in 1886 this alternative rule was adopted as the sole rule. It is—
English R = L × S ÷ 6,000 (I.)
This important step was taken after a careful and exhaustive inquiry conducted by a special committee appointed by the Council, Y.R.A., and presided over by Sir William Forwood. The committee took the evidence of our most noted yacht architects, and finally reported in favour of Rule (I), and of the present classification (except 2½ rating, which was afterwards added by the Council). The report met with general approval; the Y.R.A. put its seal upon it, and gave it a tenure of seven years; subject, however, to General Rule 12, by which any change at any time can be made by the requisite majorities.