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What determines which way to mount trim tabs ( straight or angled )

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Old 12-06-2010, 10:10 AM
  #31
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Originally Posted by Wet-N-Wild View Post
What's your problem?? Why do people like you always have to talk s**t and try to start something?? You couldn't just try to help and answer the question.
with the boat being short what they mean is. if your running them even and your bouncing around in 3 footers they could dig in and force the bow to stuff causing possible death to you or hurting you and the boat. the small cats that I have been in run great without and just using the trim, boats were a trip ob 30 spectra and a twin skater 24. we ran the 30 in 4 to 5s off block island in a pokerrun at 90 it was hairy at times and only lasted ten minutes then back to the bay where it was only 2 footers and wakes. you should be fine without them even the 24 ran good in the bay running in 2 to 3s and jumping wakes from big yachts. so save your money. art
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Old 12-06-2010, 10:53 AM
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I dont know if this will help, but here are some pics of transoms from my last two boats.
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Old 12-06-2010, 11:04 AM
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Originally Posted by AIR TIME View Post
with the boat being short what they mean is. if your running them even and your bouncing around in 3 footers they could dig in and force the bow to stuff causing possible death to you or hurting you and the boat. the small cats that I have been in run great without and just using the trim, boats were a trip ob 30 spectra and a twin skater 24. we ran the 30 in 4 to 5s off block island in a pokerrun at 90 it was hairy at times and only lasted ten minutes then back to the bay where it was only 2 footers and wakes. you should be fine without them even the 24 ran good in the bay running in 2 to 3s and jumping wakes from big yachts. so save your money. art
Cool, thank you so much for the info. The shop told me to put the money to better use like full hydraulic steering. I was just wondering what that meant because i see other smaller boat with trim tabs. My boat runs and handles great, but I'm not running in the 90s yet, still need some work
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Old 12-06-2010, 03:15 PM
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Originally Posted by Smitty View Post
You should have full hydraulic steering and make sure every pivot point is tight with no play.
yup,have it ..

The 27 Carrera is prone to chine walking from the 25deg vee
and the fact it is actually made from a longer boat.
( 30 Carrera with a 3ft plug in the mold )
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Old 12-06-2010, 03:34 PM
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I guess some clarification is needed.

Trim tabs mounted at an angle simply extend the running surface when set level or slightly above the bottom. Chine walking is a very subtle problem when it starts, and gets progressively worse with each rebounding cycle. Therefore you want to stop it with a slight subtle "nudge". To do this you insert a small outer corner of two opposing trim tabs into the water flowing off the bottom which creates a stabilizing (centering) affect on the hull without increasing drag beyond the bare minimum. You can't do this with angled tabs since they are an "all or nothing" proposition. You either put the entire tab surface in the water...or take it out. The Bennett style tabs shown in most of the pictures above are used more to help in planing and holding the bow down than to reduce chine walking, and they are a medium duty unit rather than a high performance tab. In addition when you mount tabs at an angle you are creating a "hook" at the transom which will create more bow steer and scrub speed. The only reason I can see where this might improve a hull is if the builder or rigger put too much rocker into the hull, or the C/G is too far aft, and you need artificial means to correct what is basically a flaw in construction, rigging, or design.

The hull that started this thread has an extremely deep vee and certainly could benefit from properly fitted and mounted tabs IMHO.

I hope this helps.

T2x

Last edited by T2x; 12-06-2010 at 03:37 PM.
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Old 12-06-2010, 03:37 PM
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Lavey did it both ways and flat works better on my hull.

Uncle Dave
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Old 12-07-2010, 10:53 AM
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Thank you all for your input, I will try mounting them straight and see how I like,
since i dont have any tabs right now i think I will like it..
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Old 12-07-2010, 12:13 PM
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Also remember that where you mount the tabs on the transom - whether it be angled or straight across - makes a difference too.

Most folks mount tabs all the way out towards the chines. I talked to a number of folks and looked at lots of pictures of Progression 22's before electing to mount mine a bit further in - over the lifting strakes. Why? Take a look at the picture below and note where the tabs are a just under 80 MPH. If I mounted them at the chines, no matter how low I dropped them, not much would happen at speed.

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Old 12-07-2010, 12:16 PM
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Flat mounted tabs on my Donzi. Rarely need to use them except in quartering seas.

With my Kryptonite, the angled tabs gave me more length and I ran them even with the bottom and a touch down in following seas.

As T2X said, different set ups depending on how they are being used.
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Old 12-07-2010, 03:54 PM
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generally for top end, flat. but general use (i.e., all around use) level with the hull.

Flat tabs really won't do much to help you with a list from weight, etc. while cruising. So if you want to use them for the all purpose tab use, angled is best. if you really want to fly top out, generally flat is best.
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