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Old 03-17-2019, 11:49 PM   #1
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Trim Tabs for 12í RIB?

I have trim tabs on both my old rib and my bullfrog, the new rib has significantly more horsepower but the bow comes way up when jumping on a plane and it porpoises a bit at low speed plane. Are trim tabs really that effective, I for the life of me canít seem to think of anything else different? If so what brand do you like best.

Thanks!
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Old 03-18-2019, 12:42 AM   #2
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I’ve been playing with the problem of bow rise and I’ve decided you need some planing surface aft of the transom. Fixed or spring type trim tabs solve the problem nicely. I don’t know why more small boats aren’t designed with surface area aft of the transom.
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Old 03-18-2019, 01:21 AM   #3
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I added the spring type of tabs, cannot remember the name of them, on a previous RIB and they worked well.
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Old 03-18-2019, 05:09 AM   #4
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Some small RIBS benefit from a hydrofoil on the outboard. Doelfin, Stingray, Whaletail, choose your poison I don't have experience with any of them but when I see one on a RIB I have always asked how they work and the answer has almost always been something like "good." Downside is there is no adjustment, so they work or they don't but there is no tweak. They may also shave a little speed off top end and get in the way

There are three types of trim tabs for a small RIB to consider

Fixed: Cheapest, adjustable but not underway, includes "wedges"

Spring Loaded: Bennett and Nauticus and maybe others, offer more tab when you need it to get on plane, and less as speed increases, some adjustability but not underway

Electric: Bennett and Lenco and others, fully operational trim tabs that are just the actuators, planes and control at helm. Best and most expensive

There are also "intercepters." These sound just wrong but really work. I don't believe any of the manufacturers make any small enough for a RIB, but fixed intercepters would be easy to fabricate and would be adjustable, but not underway.

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Old 03-18-2019, 06:27 AM   #5
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Thanks all, I think I’ll give the Nauticus a try, plus ordered the Davis hydrofoil, it’s likely less effective than the larger ones but I need to be able to walk around the boat so a large fin like the whaletail is out.
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Old 03-18-2019, 07:10 AM   #6
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Quote:
Originally Posted by Arthurc View Post
Thanks all, I think Iíll give the Nauticus a try, plus ordered the Davis hydrofoil, itís likely less effective than the larger ones but I need to be able to walk around the boat so a large fin like the whaletail is out.

Addition of a Doel-Fin changed our 10-6 Caribe with a 15 HP from bow-high & unstable to quick-planing and steady. No more bow attitude. With only one person, it was almost scary. EZPZ install, no maintenance. A friend had the gas shock tabs on their AB, mostly they were replacing the springs. Rarely functioned as intended.Great concept, lousy implementation.
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Old 03-18-2019, 07:21 AM   #7
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I would try the hydrofoil first, you may not need tabs if it works



Quote:
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Thanks all, I think Iíll give the Nauticus a try, plus ordered the Davis hydrofoil, itís likely less effective than the larger ones but I need to be able to walk around the boat so a large fin like the whaletail is out.
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Old 03-18-2019, 07:40 AM   #8
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Yep, I plan on installing it first, plus I’m a bit worried the tabs will monkey with the airmar transom mount transducer which I have yet to install.
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Old 03-18-2019, 07:41 AM   #9
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I have a Diel fin

Quote:
Originally Posted by Arthurc View Post
Thanks all, I think Iíll give the Nauticus a try, plus ordered the Davis hydrofoil, itís likely less effective than the larger ones but I need to be able to walk around the boat so a large fin like the whaletail is out.
On my 12 foot dinghy with 15hp engine. It came with the boat when bought three years ago, so I donít know about performance before install. My boat gets on plane with four adults and seems stable and under control at all speeds.

These characteristics may come from the dinghy versus the fin. The dinghy is a west marine 350 with 19 inch tubes.

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Old 03-18-2019, 07:50 AM   #10
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Quote:
Originally Posted by Arthurc View Post
Thanks all, I think Iíll give the Nauticus a try, plus ordered the Davis hydrofoil, itís likely less effective than the larger ones but I need to be able to walk around the boat so a large fin like the whaletail is out.
I have the Nauticus and Iím pleased. Be aware that they say not to use a hydrofoil with the tabs. I had a foil and had to remove it.
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Old 03-18-2019, 09:35 AM   #11
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Originally Posted by Arthurc
Thanks all, I think Iíll give the Nauticus a try, plus ordered the Davis hydrofoil, itís likely less effective than the larger ones but I need to be able to walk around the boat so a large fin like the whaletail is out.


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I would try the hydrofoil first, you may not need tabs if it works
While the Nauticus product has been around for awhile, I think the Bennett spring loaded units to have cleaner look and are more robust. I may not be entirely objective:
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Old 03-18-2019, 10:08 AM   #12
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Somnetimes just changing the hieght of the motor on the transome will give better results.
I have had great results with the Nauticus tabs on 3 different RIBS now - some fairly high powered. They were adjustable enough to alleviate bow lift and porpoising on one RIB which had a larger tendency to porpoise without them.
Never have I favored attachments to outboards or outdrives as they always seem to lend at least one negative attribute.
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