What is the prefered Trim Tab Size?

Carl · Post by **Carl** » May 23rd, '08, 14:35

To squeeze every ounce of fuel economy out of the boat this year, I think I will be putting tabs on her this year.

What size tabs are best for our 31's? Looking at the Bennett site they reccomend a tab size of 36 x 9", I am thinking that is too large.

Thanks,
Carl

Hyena Love · Post by **Hyena Love** » May 23rd, '08, 16:17

I believe the answer is 0 x 0. Absolutely no bigger than that.

Bennett is the recommended brand, although at this size, go with the cheapest you can find. And, just your luck, I have a set this very size for sale right now.

Harv · Post by **Harv** » May 23rd, '08, 18:00

36 x 9 is perfect. It's exactly what I have on my boat.
make sure to mount them as far outboard from the keel as possible.
You will probably have to shim the outter & inner portions of the tab mounts.
Before

After

Charlie J · Post by **Charlie J** » May 23rd, '08, 19:07

harv
thats one big ass stern running light you have there

Harv · Post by **Harv** » May 23rd, '08, 19:55

Charlie,

when we originally got the boat, there was the one light on the stern pointing into the water, and one light on the goal posts, pointing at the deck. When I pulled the posts and put up a real arch, I put 2 lights on the arch and did away with the one on the transom. Maybe before she hits the water, I'll put some underwater lights in the transom.

Ironman · Post by **Ironman** » May 23rd, '08, 20:22

I had big 36in wide...IMO too big w/Cummins I shortened them by 12in each..Less drag I think,still work good..
Wayne

Carl · Post by **Carl** » May 24th, '08, 06:37

Thank you.

Still seems real big...I could always cut down if needed.

I believe the answer is 0 x 0. Absolutely no bigger than that.

Hyena Love, I hear you loud and clear and for 12 years I ran without them. Running 18 knots and up, I agree I don't think there is any reason for them.

Since I put a larger tank in and have more weight aft I find in the 16-18 knot range the boat reaaly just squats. On those days I have "no place to be" or want to run a mile or so for another drift I like to run slow, tabs would be helpfull. Then there are the days that are really snotty and it a pain squatting thru big water. Then the nights I can only see so far, I can run faster then a dispacement but but see fast enough to be going 18 knots. It's those times I can really see the benefit of tabs.

My last boat I was able to pick up 1-2knots at the same rpm just by bringing down the bow...

Again thanks...

keysdisease · Post by **keysdisease** » May 24th, '08, 07:52

Hello Gentlemen,

Boats are designed to run on an even keel within a specific range of bow up attitude when on plane.

Boats will run just fine without trim tabs, almost all will run better with.

Trim tabs allow a boat to get on plane faster, stay on plane at slower speeds, run on an even keel regardless of load inbalance, wind and wave conditions.

When installed properly they have negative angle, which means that when retracted they are above the bottom and do not affect attitude.

Re larger sizes, it is more efficient to depress a larger tab a little to get the desired effect than to depress a smaller tab alot to get the same effect.

Some boaters with flow meters know for sure that tabs can contribute to some real fuel savings by keeping that deep V in the "sweet spot" attitude at lower throttle settings saving fuel and extending range.

Those 36 x 9's look just right to me.

Steve Moyer

Carl · Post by **Carl** » May 24th, '08, 10:38

They are ordered...

Harv · Post by **Harv** » May 24th, '08, 15:19

It's real nice to point the bow down on a snotty head sea, and plow right through as opposed to going up, over, and bang.
Just ask Charlie Johnson.

Charlie J · Post by **Charlie J** » May 24th, '08, 16:45

yea cant forget that trip harv, 10s and a ocassional 12 thrown in, your right

bertram31.com

What is the prefered Trim Tab Size?

What is the prefered Trim Tab Size?

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