Gyradius Measurements of Olympic Class Dinghies and Keel Boats

Modern construction techniques allow dinghy hulls to be built well under the minimum weight specified by the class rules. This has lead to a trend, notably in the Olympic dinghy classes, towards hulls with light ends, especially light bows. A number of classes, of which the Finn was the first, have therefore introduced means of measuring the fore and aft weight distribution. Measurements of the pitch and yaw gyradii of Flying Dutchman hulls made at the 1976, 1984 and 1988 Olympic regattas, as well as data for a number of other classes are presented. The various methods used for gyradius measurement are compared, with special emphasis on their precision, accuracy, worldwide reproducibility and the systematic corrections required. Calculations of the contribution of each of the components, including the crew, to the total moment of inertia are presented for Flying Dutchmen.