Trim angle

Hello,

How do you determine the trim angle(s) of a flat bottom planing hulls? Currently looking at calculating various hydrodynamic drag and lift for a flat bottomed hull.

I ask as I am calculating the varying drag will velocity starting from 0 m/s. I've just used skin friction to calculate the drag whilst the hull is in displacement mode, then when it reaches hull speed I will begin to include hydrodynamic drag.

Am I on the right track?

Thank you,

 

Maximum lift of a typical aircraft is achieved at 10 degrees. I think planing hulls are about the same however more variation should be expected because of the wide variation in hull shapes, displacements and aspect ratios. If you have access to a lot of Trailer Boat Magazines you could look at many performance graphs and take stock of the speeds where greatest efficiency is achieved. FB hulls will require less trim angles than all other shapes. On long and light FB hulls very low trim angles are the norm whereas on heavy and short hulls high trim angles are required, especially at lower planing speeds. My 2 cents.