This document forms part of the validation of Formation Design Systems' seakeeping software Seakeeper. The Seakeeper program is fully integrated into the Maxsurf naval architecture design suite.

Seakeeper uses Strip Theory (Salvesen et al. 1970) to predict the heave and pitch response of a vessel in a seaway. Conformal mapping methods and inviscid flow calculations are used to compute the section added mass and damping.

Calculations are presented for a standard series of catamaran forms tested at the University of Southampton (Molland et al. 1995, Couser 1996). The results from Seakeeper are compared with those from towing tank measurements for three Length:Displacement ratios, two demihull separations (and single demihull in isolation) for three different speeds. The hullforms tested were based on the NPL round bilge series (Bailey 1976) see Figure 1; the hulls having been stretched in the longitudinal direction to give suitable Length:Displacement ratios. A summary of the test conditions is given below:

Model principal particulars

Separations tested: S/L = 0.2, 0.4, Monohull

Speeds tested: F_n = 0.20, 0.53, 0.80.

Tank Dimensions

All tests were conducted in head seas.