87MagnumII

is it possible for a set of trim tabs to interfere with bow lift even if they are in the fully retracted position?? I have seen boats identical to mine in make/model/power plant get some really good bow lift but mine wont come up like it should, the only difference is mine has a big set of tabs on it and the others dont. I also think the the lack of lift is hampering my top speed due to more drag, any feedback would be appreciated.

1987 Concord Magnum II
260HP Mercruiser 5.7L
21P Laser II prop

http://www.concordboats.com/Magnum-II.html

ezstriper

I would not think so if they retract all the way above the hull, a lot of things can effect lift, props, hull weight and weight placement, waterlogged area of the boat..

GTOFFSHORE

Just pull them and try without. Not very hard just leave the rams and try it out. You can have too much of a tab on a boat or bad placement if added later on.

Too Stroked

It is possible for trim tabs to negatively affect top end in several ways. First, if the bottom of the tab plates are too close to the running surface / bottom of the boat, they will cause drag. We generally mount them at least 1/4" up on the transom from the planing bottom.

Second - and as you said - if the tabs are mounted in such a way as to drag in the water even when fully retracted, you'll get drag. On tabs where you can change where the bottom of the ram attaches to the tab itself, you can sometimes move the mounting outward - which effectively raises the tab.

Finally, if the tabs are mounted too far down into the v (on a vee hull), they'll be dragging all of the time. On the other hand, mounting them too far outward / away from the center of the boat can lead to tabs that almost never contact the water - until it's too late.

Remember, there are other things that affect bow lift too. Things like fuel load, prop, engine / drive combination, x-dimension, etc.