UNDERSTANDING THE PHYSICS OF TRIM

Relative rotative efficiencyFunction of the torque in openwater (Q ow ) and torque behindship (Q ship ) :ηRRQ=QowshipRelative rotative efficiency1.011.000.99Fn=0.128Fn=0.164Fn=0.201The moment measured on theship/model differs from themoment in open water due tonon-uniform flow and the level ofturbulence.Trim (m)0.98-2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2Results for Froude number = 0.128Trim -2.0m 0.0m 2.0mη RR [-] 1.005 0.988 0.982Δη RR [-] 1.7% 0.0% -0.6%ΔP D ηRR [%] -1.7% 0.0% 0.6%