The
Universal rating rule encourages heavy displacement boats, and a maximum displacement credit is set at (0.2*LWL + 0.5)^3 cubic feet for the various rating classes, or what was called "normal displacement" by
Norman Skene. Students of yacht design with a knack for metric conversions will recognize the normal displacement as the same value as minimum displacement allowed without penalty under the International Rule. Thus, most boats designed under the Universal and International rules had the same displacement for a given waterline length. This worked out fine for boats down to the size of a Universal R class, and the slightly smaller International 6 meters are a bit heavy for their length. The very small International 2.4 meters have a minimum displacement of (0.2*LWL + 0.06)^3 cubic meters and the
proposed 4.6 meter class minimum displacement is ((0.2*LWL + 0.10)^3 cubic meters instead of the (0.2*LWL + 0.15)^3 cubic meters for the 6, 8, and 12 meter classes. The effects of this reduction in minimum displacement for the smaller classes is shown in the illustration, which shows the rise in the displacement/length ratio for normal displacement at waterline lengths of less than 20 feet.
While all this seems archaic given that the Universal and International rating rules began over one hundred years ago, the 2.4, 6, 8, and 12 meter classes are still active under the International rule, and the
Universal rule still has a pulse with the J class.
