Ted's recommendations were used for the optimal values, with a minimum of 25 and a maximum of 50. This ratio appears to be lower now than in older designs. Wide boats are popular today since they provide form stability and large interior volume. On the downside, excess beam contributes to poor balance, distorted heeled waterlines, and high inverted stability. The roll period is based on the moment of inertia, waterline length, and beam.
Large values resist rolling forces.
A heavy rig can greatly increase I, with little impact on displacement. This equation was developed to support the 1987 Fastnet race investigation. Simply stated, a sailboat's roll period, in seconds, is inversely proportional to its stability. Tender boats have long periods, stiff boats have short periods. Then measure the time it takes for ten full cycles , and divide by 10.