I have screw heads underneath my trim tabs, normal? (see pics)

[Pursuit2150]

Re: I have screw heads underneath my trim tabs, normal? (see pics)

The "SMALL HEADS" of any screws or bolts you will use will have "0" impact on the speed of the boat.
Case in point can you figure the "drag" impact on the engine shaft,transducer,swim platform, etc.?
You are not in the American Cup Race..
The trims on a boat are much the same as on an aircraft, not 100 percent of the water is in contact with the entire fin.
It's all about air & fluid dymatics.

If really worried, use SS pan-head screws.

 

[MikDee]

Re: I have screw heads underneath my trim tabs, normal? (see pics)

This is what drives me nuts about trim tab installations. They are not supposed to be flush with the bottom. They are supposed to be mounted up at least a 1/4". Otherwise you can never get them out of the water. IE - they're always affecting the attitude of the hull.

In my opinion the best option is the recessed tabs. When they're fully up they become part of the hull. Nothing behind the transom. Gotta love a Hewes.

I'm with Dhadley on this one, the drag of the tabs not being mounted above the hull, combined by the slight down angle of them fully retracted, is WAY more then a coupla screw heads in plate! Think about this, on full plane all boats are never completely out of the water at the trailing edge of the transom, And the water closely following the boat is actually higher then the bottom of the boat, so you would need a negative angle on your trim tabs to keep them from creating drag! Along with being mounted above the transom.

IMO I think they should be mounted about 1/2" above the bottom to start with. I wouldn't worry about a few screw heads, you have bigger issues going on here. Good Luck, Mike

 

[Dhadley]

Re: I have screw heads underneath my trim tabs, normal? (see pics)

If you really want to see what effect the tabs are having, unbolt the cylinder from the plate and tie everything up out of the way. Then go for a ride. Most likely you'll get more bow rise on holeshost but the big issue is going to be the difference in cruise and top end. It wouldn't hurt to go for a ride as is and make notes of speed, rpm and ride. Then unbolt the tabs an test again.

Regardless, they are not mounted correctly now. If it takes that much down tab to make the boat handle properly, something else is wrong.

 

[Dhadley]

Re: I have screw heads underneath my trim tabs, normal? (see pics)

And as for the drag the screws have, it'll be unmeasurable on that hull. The hook in the hull has way more effect than those screw heads will ever have.

 

[Pursuit2150]

Re: I have screw heads underneath my trim tabs, normal? (see pics)

Ditto I think that is what I stated!
"no Noticeable DRAG, that can be measured....

 

[PhatboyC]

Re: I have screw heads underneath my trim tabs, normal? (see pics)

I'm not worry about the screws underneath the tabs anymore. Obviously I have bigger problems with my negative angle of the tabs. I sent an email to the dealer last week. Explaining the problem and the solution (switching to 12"x12" edge mount) suggested by Lenco. I asked them if they can send someone or just ship me the parts. Silicone and tabs. I'm still waiting for an answer. Good thing it's winter and -12C.