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Trim tab sizing

Old 11-03-2016, 04:57 PM
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Default Trim tab sizing

In Trim Tab sizing which number is the Port to Starboard measurement . For example 9 x 12. Also what would be a good size for a 20 Ft. Grady White 150 HP (2500 lbs).....Thanks
Old 11-03-2016, 05:01 PM
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ibn a 9x12 they are 12" wide and 9" front to back. i have 12x12 tabs on my boat. my friend has 9x12s on her 24 skeeter. i prefer the bigger ones when running a heavier load.
Old 11-03-2016, 05:12 PM
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Go with which ever one will fit and you have plenty of clearance from ODs or OB foot. Having too big just means they work faster. Having too small means you wasted money!!!!!

I have a pair of Bennett drop fines that I order for my heavy Proline but boat burned up. I believe they are 24" x 12." I cant use them on boat I just bought because stern has a recurve in it. If interested let me know. I take 1/2 price for them.
Old 11-03-2016, 05:17 PM
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The info is here.
http://www.bennetttrimtabs.com/tab-sizing-guidelines/
Old 11-03-2016, 05:32 PM
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Go big, you'll be disappointed if they dont get the job done. The ones on my seabird are 12*18, glad I didnt go smaller.
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Old 11-03-2016, 05:37 PM
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Any swim ladder that will interfere? If not, 12x9 will work just fine. I have 12x4 Lenco limited space tabs because of my swim ladder and they work just fine on my 2101 CC Striper
Old 11-04-2016, 05:25 AM
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If it were my boat I would choice the 12 x 12s for best results.

For Bennett the side to side measurements are first and the fore to aft measurements are second. For some reason Lenco is the other way around.

We do make a 12 x 12 that needs very little height to mount if need be.



I hope this helps, let me now if you have any questions.

Tom McGow
Bennett Marine
Old 06-14-2018, 02:54 PM
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What size tabs would I need? I seem to be getting conflicting information. I have an alumium 30' single sterndrive that weighs 12k. I was told an inch wide per foot and confirmed that on bennett's website. So in that regard I would need 30" x 9" per side. Is there a more accurate square inch formula to determine different length and widths that would work? For example 30x9 is 270 Sq in so an 18x16 is 288 sq in or 15x20 is 300 sq in. Is there a way to figure out trim tab size in regard to boat length or weight using surface area?
Old 06-14-2018, 04:17 PM
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Originally Posted by Senior Ron View Post
In Trim Tab sizing which number is the Port to Starboard measurement . For example 9 x 12. Also what would be a good size for a 20 Ft. Grady White 150 HP (2500 lbs).....Thanks
I have 9X9 Lencos on our BW Outrage 190 with 150 horse Merc, bare hull weight about 2100 pounds. They are plenty and very responsive and make a huge difference in ride quality and overall handling especially in chop and also drop the planning speed (even more so in combo with a Rev 4 prop).

Last edited by high'n'dry; 06-14-2018 at 08:22 PM.
Old 06-14-2018, 08:05 PM
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Originally Posted by Garth.stephen View Post
What size tabs would I need? I seem to be getting conflicting information. I have an alumium 30' single sterndrive that weighs 12k. I was told an inch wide per foot and confirmed that on bennett's website. So in that regard I would need 30" x 9" per side. Is there a more accurate square inch formula to determine different length and widths that would work? For example 30x9 is 270 Sq in so an 18x16 is 288 sq in or 15x20 is 300 sq in. Is there a way to figure out trim tab size in regard to boat length or weight using surface area?
Can you tell me the make of boat and possibly post a photo of the transom or send it to Tabmanhelp@gmail.com ? I would be delighted to give you some specific recommendations.

Tom McGow
Bennett Marine
Old 06-14-2018, 09:52 PM
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Originally Posted by Tabman View Post
Can you tell me the make of boat and possibly post a photo of the transom or send it to Tabmanhelp@gmail.com ? I would be delighted to give you some specific recommendations.

Tom McGow
Bennett Marine
I sent you an email. I don’t have enough posts to post pictures yet lol.

For anyone else watching this post, my tabs are 18in wide by 12in long for a 30 foot 12k lb aluminum boat. The tabs are about 1” over the chines and I have a support for the swim step. If I maintained the 3” gap from the chines I have 15” width on the transom before I hit the support for the step.
Old 06-15-2018, 06:17 AM
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Yeah, bigger is better. I made the mistake of putting 9x9 edge mount Lencos on my 22' bay boat. Not nearly enough tab. I should have gone with 12x9, but I didn't want the tabs to extend past the strakes. I sure don't want to move the actuators. About the only things mine are good for are to eliminate porpoising and adjusting list for load imbalance. Hopefully, I can just replace the blades.
Old 06-15-2018, 07:02 AM
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Bigger is not necessarily better - correctly matched is best. A friend fitted oversize tabs to a 21ft boat and said they were a nightmare - the slightest touch and the boat would react too much - he said it was almost impossible to get them right.
Old 06-15-2018, 07:22 AM
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Originally Posted by Clinker View Post
Bigger is not necessarily better - correctly matched is best. A friend fitted oversize tabs to a 21ft boat and said they were a nightmare - the slightest touch and the boat would react too much - he said it was almost impossible to get them right.
Do you know what size he went with?
Old 06-15-2018, 09:44 AM
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Originally Posted by Clinker View Post
Bigger is not necessarily better - correctly matched is best. A friend fitted oversize tabs to a 21ft boat and said they were a nightmare - the slightest touch and the boat would react too much - he said it was almost impossible to get them right.
What size did he put on and what size should he have gotten? I have a 21' bay boat and per the Bennett website, there are about 3 or 4 different models that would work on a 21' boat.
Old 06-15-2018, 12:17 PM
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On a 21 ft Bay Boat I would suggest a 12 x 12 BOLT electric Trim Tab system. If there is a swim platform and / or ladder you need to use our edge mount Tabs.

Tom
Bennett Marine
Old 06-15-2018, 12:26 PM
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Originally Posted by Tabman View Post
On a 21 ft Bay Boat I would suggest a 12 x 12 BOLT electric Trim Tab system. If there is a swim platform and / or ladder you need to use our edge mount Tabs.

Tom
Bennett Marine
I remember not too long ago the recommendation would be to use a width in INCHES approximately the length in feet of the boat x 9". And if the width was much under to jump up to the 12".

Funny now days it seems like the 12x12 is the universal size for almost every boat between 19 and 25 feet. Transoms are not as simple and straight as they used to be I am sure is the reason.
Old 06-15-2018, 02:10 PM
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Originally Posted by Jonboater View Post
I remember not too long ago the recommendation would be to use a width in INCHES approximately the length in feet of the boat x 9". And if the width was much under to jump up to the 12".

Funny now days it seems like the 12x12 is the universal size for almost every boat between 19 and 25 feet. Transoms are not as simple and straight as they used to be I am sure is the reason.
Yup, that's pretty much the reason, plus more transducers, platforms, power poles, etc. than there used to be too!

Tom
Bennett Marine.

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