32 caliber

Does amyone know why the trim tabs are mounted on an angle, usually the same angle as the hull ? When running on the water the boat is level, not on an angle like the hull. It would seem that if they were 90* to the water when running that they would hold the bow down better. When they are in the down position they are also angled out, which would put a drag on the boat when moving. Has anyone ever tried mounting them at 90* ?

Pismo10

Many performance boats mount their tabs flat or flater than the vee of the hull. Some of Fountains top boats are dead flat all the way at the edge.

32 caliber

Well then I guess I'm not to far off in my thinking....I was thinking about repositioning them.....I'll wait and see if anyone else has any opinions....

32 caliber

I just found a number of pics on fountains with the tabs mounted straight, or 90 degrees to the water, not on an angle matching the hull...hmm...I think I'm on the right track here with my opinion....

mmwalters

Some velocitys also mounted the tabs flat with the deck. If you were to look back at the bottom of the boat at speed the water comes off the bottom at the angle of the bottom. It would only be flat if the bottom were flat

32 caliber

If thats the case, look at the bottom pic, the hull isn't flat, and the tabs don't match the angle of the hull.....

mcrsr

it doesn't make sense, though, if you have it mounted flat, perfectly in line w/ the hull what happens when your running the boat w/ the bow high? dont't the tabs drag in the water and slow the boat down? mine are set up that way and i am considering raising them

mmwalters

Jim I agree, the bottom is flat only in the area of the chines. I believe on a pad bottom like a velocity, the pad lifts the boat so high at speed that the v section on both sides of the pad have little contact with the water. Maybe that explains the flat mounting. I have seen both mounting positions on race boats. The most common by far is the tab at the angle with the bottom.

mmwalters

mcrsr You sure don't want the tabs to drag at speed. It is common to mount tabs 3/4'' above the bottom so they will not drag. There should be enough UP angle so the tabs do not touch when the boat is trimed out. Remember the best running angle on a well set up hull is only 2-4 degrees

32 caliber

From what I could find, it seems all the newer fountains have the tabs 90* to the water, the older ones are on an angle equal to the v hull. They must of changed it for good reason...it wouldn't be a very big deal to reposition mine, maybe I need to make the change and then see what difference it really makes....