turn fins on tub

[Kim J]

Thanks again Charles.

BTW This is in contradiction to post # 33 !

 

[Marty Davis]

More questions Charles :

What are the symptoms of a misplaced fin - too much forward or aft ?

Kim J, when I build a new boat (most of my boats are scratch built) I make the turn fin mount, with the help of an adjustable bracket, so that I can move it forward or backwards to find the optimum position. The turn fin itself is also sacrificed. Starting with a fin that is to large, I trim it until it is slightly too small, then I back up to the last size that worked well and make a new fin that size.

Considering that everything else is as it should be, a turn fin that is too far forward of the COG will mke the boat turn sluggish using more rudder travel. A turn fin that is too far behind the COG will make the boat turn too snappy, too sensitive in the straights and in the turns. When the turn fin is correct as you put the boat in the turn, you only have to use a small amount of rudder travel and hold the rudder in that position as the boat continues thru the turn. You will know when you have acheived the correct turn fin and position.

Charles:

With the fins that I run, having the fin too far forward makes the turn too snappy and too far back not enough turning. Opposite of what you are saying.

Wonder why this is?

 

[Charles Perdue]

Hello Marty, that is one of the handling differences between the flat turn fin and the curved turn fin. With the front to back positioning of the flat turn fin the boat reacts similar to lenghtening or shortening the wheel base on a car. Like the differences between the Funny Cars and the Top fuel Dragsters.

Charles