The Seawanhaka rule is therefore superior to ours if excessive length be feared; and being a plus formula, it lends itself readily to the adoption of any desired tax on other linear dimensions.
For instance, Mr. Watson's proposal (II.) might be put into the plus form, thus:—
American R = (2L +2B + D + √S) ÷ 3.8 (VI.)
This shows the value of a plus rule over a multiplying rule and the value is not lost when a plus rule is converted into an English rating rule by cubing the former and dividing by a constant. Thus, the recent Rule Committee proposed to convert the Seawanhaka rule into an English rating rule by cubing it and dividing by 6,000, the result being:
English R = (L + √S)3 ÷ constant, say 48,000 (VII.)
The variable within brackets in VI. can be cubed and divided by a constant in a similar manner. But the cubic forms of the 'plus' rules are clumsy, and seem difficult to those who cannot compute by logarithms. No real advantage is gained by adhering to the English rating and time scale and classification. In fact, the American time scale is simpler. If, therefore, a 'plus form' of rating be ever adopted, it would be much better to adopt 'corrected length' as the rating, together with the American time scale. The classification could, of course, be chosen in such a manner that our own racing yachts would be at the top of the classes without any important alterations.
Another rule was proposed in a leading article of the 'Field' on October 15, 1892. It is:—
English R = L2 √S ÷ constant, say 6,000 (VIII.)
It gives a sail-curve nearly parallel to the one produced by the New York rule, and may almost be regarded as that rule dressed in Y.R.A. uniform; but the advantages of a plus rule are lost, whereas in the conversion of the Seawanhaka rule proposed by the Y.R.A. Committee 1892 they are retained.
Similarly, the Y.R.A. rule—varying as [3]√L.S. (see [V.]), or as [3]√L. × √S. × √S.—may be considered as equivalent to the plus formula L. + 2 √S. ÷ constant, and the English and American rules may therefore be regarded to vary as follows: