An examination of this form of the Y.R.A. rule is interesting. By cubing V. and comparing it with I., it will be seen that six thousand times the English rating equals the cube of the American rating derived from formula V.
Diagram of sail curves, showing the relation of sail to L.W.L. in the Y.R.A., New York, and Seawanhaka Rules. 40-rating class.
When English and American rules are examined diagraphically, the sail-curves take three positions that differ considerably in their steepness—the Y.R.A. rule giving a curve nearest to the horizontal which indicates R. = S. ÷ constant, proposed by Mr. Richardson in 1886 (or R. = √S ÷ constant if expressed in American measure; or R. = S. √S divided by a constant if expressed in English measure); and the New York rule taking a position nearest to the vertical denoting R. = L., under which the Solent Length Classes used to sail.
The Seawanhaka rule gives an intermediate curve—perhaps the 'happy medium.'
The curves have been plotted for yachts of 40-rating by our rule, and the following table gives the actual numbers:—
| L.W.L. | Sail-area allowed to | ||
| 40-raters, Y.R.A. Rule | 61.5 Corrected L. Seawanhaka Rule | 61 Corrected L. New York Rule | |
| ft. | ft. | ft. | ft. |
| 54 | 4,444 | 4,761 | — |
| 56 | 4,286 | 4,489 | 5,041 |
| 58 | 4,139 | 4,225 | — |
| 59 | 4,068 | 4,096 | 4,096 |
| 60 | 4,000 | 3,969 | — |
| 62 | 3,871 | 3,721 | 3,481 |
| 64 | 3,750 | 3,481 | — |