Universal Rule - changes from 1903-1931

Yacht racing - rating and design

[Note, The following was valid as of 1935. All measurments use the imperial (ft., lbs.) system. Ed.]

1903

First developed by the New York Yacht Club, at this time it is better defined as the "Rating Measurement, New York Yacht Club."

L x √SA = Rating.
5 ∛D

The mean of the length overall, exclusive of bulwarks and rail, and of the length on the load water plane, both measurements to be taken parallel to the middle vertical plane and at a distance from it equal to one-quarter of the greatest beam at the load waterline.

In case the width of the stern on deck exceeds one-half the greatest beam at the load waterline, the measurement for the length overall shall be taken to a point abaft the stern, where the continuation of the fair line of the top edge of the planksheer would intersect the quarter-beam line.

Displacement to be obtained by areas of cross sections, load waterline divided into five parts.

One-half of any excess of load waterline over 115 per cent of L shall be added to racing measurement.

Limit of draft in feet 0.133 rating plus 2.66. Any excess over this limit to be multiplied by 2 and added to the rating measurement.

Limit of sail area. Any excess of the square root of the sail area over 135 per cent of L shall be added to the rating measurement.

The draft of any vessel, not including centerboard, shall not exceed 18 feet.

1904

Constant for the cube root of D "displacement" increased from 5 to 5.5.

L x √SA = Rating.
5.5 ∛D

1905

Length L measured on a line parallel with the middle fore and aft vertical plane at a distance from it equal to it of one-quarter of the greatest beam at the load waterline, and one-tenth of this beam above the load waterline ; and in case there are any notches, jogs, curves or angles, at or near the plane of measurement, L shall be taken on a fair line bridging such notches, jogs, curves or angles.

Limit of draft 0.15 times L plus 2.50; and any excess of draft, exclusive of centerboard, as per above formula, shall be multiplied by three and added to rating measurement. This penalty not to apply to yachts launched or keels laid prior to January 1, 1905.

Developed by the NYYC as the "Rating Measurement, New York Yacht Club", with these changes it was widely adopted in North America, and commonly referred to as the "American Rule".

1906-1908.

No changes.

1909

Constant 0.18 substituted as multipher for entire formula in place of 5.5 for D

0.18 L x √SA = Rating.
∛D

L shall be the load waterline length plus one-half the excess of the quarter-beam length over the percentage of the load waterline length given by the formula, Percentage = 100 -sqrtL.W_L. provided, however, that in all boats over one hundred feet L.W.L. the percentage shall be 90.

Displacement. The load waterline to be divided into ten equal parts in place of five.

Limit of draft 0.16 times L.W.L. plus 1.75. Any excess to be multiplied by three and added to the rating. This penalty not to apply to yachts launched or keel laid prior to January 1, 1909.

With these changes, the "American Rule" was accepted in Europe and finally, formally became the "Universal Rule" although Europe had developed the "International Rule."

1913

Establishment and marking of load waterline plane; "from which all calculations are made."

Displacement. In calculation D shall never exceed 20 per cent L.W.L. plus 0.50. Added provisions for bridging concave lines in hull.

1928

Load waterline length to be limited to 108 per cent of rating measurement plus 5.0. Any excess to be added to measurement.

Freeboard to top of covering board to be not less than 6 per cent of L.W.L. plus 0.6; the deficit to be multiplied by two and added to measurement.

The sheer to be a fair, continuous concave curve; and the tumble home on each side of the yacht shall not exceed 2 per cent of the extreme beam.

Seantlings according to established rules of classification societies or Herreshoff’s rules.

1931

L in classes 56-foot, 65-foot and 76-foot. Percentage = 100 - 1/2 L.W.L. Quarter beam measured at 1/8 of breadth above L.W.L. plane. Draft 16 per cent L.W.L. plus 1.75 with limits of 11 feet 9 inches in 56-foot; 13 feet 3 inches in 65-foot and 15 feet in 76-foot classes ; applicable to all yachts launched after May 21, 1931.

Freeboard not less than 5.7 per cent of L.W.L. plus 0.6.

Camber of deck not less than 14 inch per foot of beam.

Centerboards to be pivoted at fore end. Top of trunk not above floor; and 6 feet 6 inches below under side of deck beams. Weight not to exceed in pounds area in square feet multiplied by 0.5 of rating measurement.

Masts to weigh not less than 0.0125 cube of rating.

Note. There is no terminolgy in the rules for the terms “Class J” or ‘J-Boat”, both are common (lubberly?) misnomers. The correct and legal title of this class is 76-foot Rating Class: all other classes being similarly designated. The letters are merely symbols carried on the sails as a convenience in identifying the classes.

Comparative table for 76 rating under the Universal Rule

L.W.L.	Displacement				Draft		Freeboard	Sail Area		Mast from deck
L.W.L.	0.20L	+0.5	Cu. Ft.	Tons	0.16L	+1.75	Freeboard	√S.A.	Sq. Ft.	Mast from deck
75	15.00	15.50	3774	108.4	12.00	13.75	5.10	87.26	7614	153.3
76	15.20	15.70	3870	110.5	12.16	13.91	5.16	87.22	7608	153.3
77	15.40	15.90	4020	114.83	12.32	14.07	5.22	87.18	7600	153.2
78	15.60	16.10	4173	119.2	12.48	14.23	5.28	87.15	7595	153.1
79	15.80	16.30	4330	123.7	12.64	14.39	5.34	87.12	7589	153.1
80	16.00	16.50	4492	128.34	12.80	14.55	5.40	87.08	7583	153.0
81	16.20	16.70	4657	133.0	12.96	14.71	5.46	87.05	7577	153.0
82	16.40	16.90	4826	137.9	138.12	14.87	5.52	87.02	7572	152.9
83	16.60	17.10	5000	142.8	13.28	15.03	5.58	86.99	7566	152.8
84	16.80	17.30	5177	147.9	13.44	15.19	5.64	86.95	7560	152.8
85	17.00	17.50	5359	153.1	13.60	15.35	5.70	86.92	7555	152.7
86	17.20	17.70	5545	158.4	13.76	15.51	5.76	86.89	7549	152.7
87	17.40	17.90	5735	163.8	18.92	15.67	5.82	86.87	7546	152.6

Note: Maximum limit of L.W .L., 108 x 76 = 82.08 + 5 = 87.08.