Effect of Sinkage and Trim on Form Factor of Resistance

Abstract

In order to investigate the effect of sinkage and trim on form factor, resistance tests were condducted on two sets of geometrically similar models with keeping their trim and sinkage constant.The results of these experiments show that sinkage and trim have important effects on form factor of resistance and that form factor is nearly constant independent of ship's speed if the trim and sinkage in her runs were kept constant.

Scale effects and full-scale ship hydrodynamics: A review

“…Research on scale effects in the interim is therefore necessary. For example, would be interesting to settle the disagreement between Ferguson (1977) and Yokoo (1960) regarding sinkage and trim, explored in section 2.2.1.2. This would help progress the debate around scale effects on sinkage and trim which will find applications in shallow waters as well as in general cases.…”

“…Since sinkage and trim change considerably with Froude number, it is conceivable that form factor variations as a result of varying Froude number are a secondary effect we can correct for by modifying the mean flow velocity around the hull. This was Yokoo's (1960) approach to the problem, who presented correction formulas to modify the mean flow in an attempt to account for these phenomena. To the best of the authors' knowledge, these corrections remain untested in the literature.…”

“…So, the cause of scale effect in sinkage and trim is the form resistance itself. In essence, Ferguson (1977) saw a single phenomenon based largely on boundary layer physics and experimentation where Yokoo (1960) saw two. Although he did not explicitly state so Ferguson's (1977) conclusions are in direct contravention to established extrapolation laws.…”

“…Although he did not explicitly state so Ferguson's (1977) conclusions are in direct contravention to established extrapolation laws. On the other hand, Yokoo (1960) found a way to preserve the validity of these hypotheses by devising correction factors.…”