Mounting trim tabs on a mono hull ?

[Andris Golts]

Hi all i have heard some boaters mount the trim tabs flush with the bottom of the boat while others mount them about a 1/16'' to 3/32'' above the bottom of the hull . What are the pro's and cons of either method ? Regards Andris Golts.

[MadProps]

Mount them above, mounting them flush you will be surprised how much drag they can create , water rises as it comes off the transom of the hull

[Andris Golts]

Thanks for the reply.

[Jesse J]

Some boats don’t even need them. Try without, if set up right, shouldn’t need em.

[NativePaul]

^^^^^
I'm not a mono guy, so I cant say why, but I haven't seen an oval race boat with trim tabs here for years.

Some submerged drive Monos that run the M or triangle course and need to handle 120 degree hairpin turns have trim wedges built into the hulls though, often servo actuated and mixed into the rudder channel.

[RossCo216]

Should they be mounted closer to the strut or the turn fins? I would assume they should be equal distance between the two.

Also, are there any noticeable advantages to a dual trim tab?

[Panther6834]

Should they be mounted closer to the strut or the turn fins? I would assume they should be equal distance between the two.

Also, are there any noticeable advantages to a dual trim tab?

I'm still fairly new to FE, but I can answer your first question. Of all the boats I've seen with trim tabs, they're so closer to the strut.

In regards to dual trim tabs, I can't claim to know whether, or not, they're are any "advantages", but I can tell you this. On my ProBoat SonicWake, after replacing the stock single trim tabs with the dual trim tabs available from Boat Bitz, the boat was handling considerably better. I don't know if the dual trim tabs, themselves, had anything to do with it, or if it had to do with how I had them set. I had the sides closer to the strut parallel to the hull, and the sides closer to the turn fins up about 0.5mm.


~ More peace, love, laughter, & kindness would make the world a MUCH better place

[Jesse J]

Dual tabs: inside is for ruining straights, outside is for tuning turns. Some boats need this to be separate, others don’t. If you have dual, you can adjust independently. And definitely have them raised 1/16-3/32”.

[fweasel]

Trim tabs get mounted closer to the strut so they're in contact with the water when it's headed straight. There's a fine line of how close because of turbulence being introduced to the prop. When a mono turns, it rolls, and one tab is out. Dual trim tabs are really just wide trim tabs, useful on slightly larger hulls, and offer a finer degree of tuning between sides to custom tune the setup.

[Panther6834]

Dual tabs: inside is for ruining straights, outside is for tuning turns. Some boats need this to be separate, others don?t. If you have dual, you can adjust independently. And definitely have them raised 1/16-3/32?.

That is good information to have...but it does raise, at least for me, another question. If the outer tabs in a dual tab setup are to assist with turning, should they be higher, or lower, than the inner tabs?


~ More peace, love, laughter, & kindness would make the world a MUCH better place

[NativePaul]

Yo know that you have to run your boat without them, and see what (if any) flaws when going straight, and when turning it has that you want to correct.

[Panther6834]

Yo know that you have to run your boat without them, and see what (if any) flaws when going straight, and when turning it has that you want to correct.

While I'm waiting for the replacement from Boat Bitz, I just might do that. Will have to temporarily take over the mounting holes, but it's worth a try. But, that still doesn't answer me question...so, let me reword it this way.

When using dual trim tabs, if the outer tabs are intended to "assist" with turning, should they be higher, or lower, than the inner tabs? I'm not asking about the inner tabs...only the outer tab's position-relationship to the inner tabs.


~ More peace, love, laughter, & kindness would make the world a MUCH better place

[RossCo216]

Thanks for clarifying the dual tab function. I plan to keep running the boat without them but I did just order the carbon fiber dual tabs from OSE just in case.

Is there a general rule of offset from the strut, say 5mm beyond the prop area? Or is it just a matter of drilling holes and trying different set ups?

[jaike5]

For my Delta force snipper 44" 10s . The out side trim is set higher than the in side trim. each boat will be different (test test test). For my DFS, if the outside trim is to flat it pushes the nose down and will cause hooking coming out of the corner. You have to find the balance in race slop, not to flip, and not to hook in the corners.
J.

[Norwest]

Oh really!