planing issues solved

[hangbelly]

http://www.youtube.com/watch?v=PPpxL...layer_embedded

[RidgeRunner]

They do help. I was a believer in 1987 when I tried a DoelFin on an underpowered Stumpknocker flatbottom. (17' boat 35hp Johnson) The boat was quicker on plane with half the bow rise and the stern didn't drop coming off plane. One negative, if you trimmed it up and got it to moving, (maybe 28MPH WOT) and then trimmed the motor all the way down, the fin would bury the bow to the point of being dangerous.
I believe it is less about loosing thrust up as the illustration shows and more about surface area and lift. If you are throwing a rooster tail coming out of the hole you got different issues altogether.
I was lucky to have trim and tilt. Dole Fluid Power Products made a cast aluminum aftermarket power trim system for small outboards. It had hydraulic cylinders and clamp at the motor (like the old external trim Mercury used) and a manual hydraulic pump near the helm. To trim the motor you turned a knob and moved a lever back and forth like any hydraulic jack. Power up, gravity down. It was good for 3 or 4MPH.
The fin and power trim (human powered or otherwise) made for a much nicer setup.