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Old 20 November 2006, 14:51   #11
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Wavecrosschris, I see your asking if you should put trim tabs on your rib, the reason I did what I did in the above statement is because putting trim tabs on these tiny hulls is crazy, more to go wrong, more to bang on the trailer, and why on a hull no larger than a surf canoe, if it cant be set up without, then it's either overpowered or poor weight distribution or a bad hull, unless of course your looking for crazy speeds that is?
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Old 21 November 2006, 14:09   #12
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Trim tabs V Hydrofoils V Volvo interseptor

For general inforrmation and this is from practical "on the job" experience.
I had a large RIB that had a bad attitude problem (inbuilt from manufacture). She always was bow high in the water at standstill, cruising, full throttle, loaded or unloaded etc,etc. In large seas she was dangerous! I played with all types of additions to assist this problem. I started with the simplest and most inexpensive, Hydrofoils. Now this boat was a twin installation on legs and approx 260hp each. After initial trials (lots) in all sea conditions it was proved that the hydrofoils cartainly made a significant difference to the attitude of the boat. In other words they actually did do what it said on the tin(so to speak). However they did not satisfy me and left more improvement necessary for safe and comfortable transits. They were left in situ on the legs and trial two started. I fitted trim tabs, the largest type available with financial constraints. I cannot remember the name of these tabs but you will see them in all magazines under the Nautequipe advert. Now they are a good item but my application of them was incorrect, my boat was too heavy hence I continually broke the tab rams. On the trials with these they did in fact prove that trim tabs were the way to go. They changed the attitude of my boat instantly. It was a different vessel completely and much safer in all seas. The change was staggering! Having continued with these tabs and continually changing the rams I finally invested in the largest Bennet Trim Tabs available. At long last and after a bad financial route I settled for these and continued also with the hydrofoils. In actual fact the boat builder is now I believe fitting these tabs and also using the hydrofoils on all new builds? I am at present looking seriously at the Volvo Tabs mentioned earlier in another thread. So in summary:
Hydrofoils do actually work and work well considering their limitations on outboards, drive legs up to and including 260hp, not exactly what it says on the tin.
Trim tabs and only the correct ones are fantastic at altering the handling of badly behaved boats and in fact correctly researched and fitted make the vessel much safer at sea. I must add here that there should be no real reason for fitting any handling device other than for badly set up hulls or inherent bad build qualities? If you see a new vessel that has to have tabs etc fitted by the manufacturer to make it perform properly you have acquried the wrong vessel, personal opinion of course!
I have no experience of the new Volvo intercepter units however all reports are extremely favourable both from the installation and operating views. I also believe they are financial competitive as well? Anyone with these units fitted, I and I'm sure all members, would be very interested to know how they have been received in all aspects?
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Old 21 November 2006, 14:22   #13
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I will be fitting the interceptors to my RIB in the next few months. They are a lot cheaper than the others as they come complete with the indicators and switches etc as standard. Also on a big RIB that gets a hammering they say you should use dual rams on normal tabs which increases the cost quite a bit.
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Old 21 November 2006, 14:35   #14
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Trim Tabs et.

Yes, twin or dual rams are most certainly better and stronger. Unfortunitely it was dual rams that I continually broke on my initial tabs. The Bennet Tabs were much, much stronger and suffered no damage or breakages. If in doubt simply go for the best. I most certainly would be interested to hear your comments and results when you fit the Volvo items. Thanks.
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Old 21 November 2006, 14:55   #15
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do trim tabs add to drag and increase fuel consumption?
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Old 21 November 2006, 15:19   #16
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Trim Tab etc.

Regarding drag and fuel consumption, these are my personal findings and results. No, they do not cause drag as we know it. Consider that the tabs etc are actually raising the stern under way and extending the length, fractonally, of your hull. If fitted and utilising correct operating procedures, you will actually use your trim tabs on flat good seas, good cruising speed and achieve better fuel consumption. There is a myth that tabs are only for foul weather etc,etc. This is incorrect, they enhance all movements and attitudes of the vessel and correctly used in all conditions and weathers are brilliant. Also consider the old favourite questions "tubes in or out of the water". Well if your tubes are in contact with the water under way you are actually causing drag and increasing your fuel consumption, fact! If your tabs or hydrofoils are raising your stern under way, then you are actually assisting the vessel through the water by decreasing drag and assisting fuel consumption, fact. This is very brief for such a complicated subject. I hope it is of use to all. So again to summarise:
These items do not cause drag and yes they most certainly assist fuel consumption. Again my personal opinions.
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Old 21 November 2006, 16:28   #17
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Originally Posted by ribit View Post
Wavecrosschris, I see your asking if you should put trim tabs on your rib, the reason I did what I did in the above statement is because putting trim tabs on these tiny hulls is crazy, more to go wrong, more to bang on the trailer, and why on a hull no larger than a surf canoe, if it cant be set up without, then it's either overpowered or poor weight distribution or a bad hull, unless of course your looking for crazy speeds that is?

hmmm, I know i'm putting tabs on my boat and know they'll work! - I used to build rc powerboats (before I bought a bigger toy) and if they work on a 100cm 30mph model, they're goana work on a half-ton rib with slightly too much weight on the stern. I have bought a set of Plastimo tabs which are on adjustable rams. Basically, I know the only time I need to trim the boat (keep the bow down) is when I'm carrying people - I will just wind them down a bit when I'm carrying more load, which will give lift when I need it. When it's just me, they can run level to the hull and just increase the planing surface.

My RIB does have slightly too much power for its size (not over the max rating on the transom though) but like anything with excessive power, superbikes and cars alike, it's the person on the throttle that says whether it's in control or not.

Can't see why you wouldn't want tabs and advise not to have them - everyone I have spoken to, from the dealer I bought the boat from - a main Yamaha dealer to people with SR4's on this forum, all say tabs work?!
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Old 21 November 2006, 16:58   #18
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Originally Posted by Matal Mickey View Post
I must add here that there should be no real reason for fitting any handling device other than for badly set up hulls or inherent bad build qualities? If you see a new vessel that has to have tabs etc fitted by the manufacturer to make it perform properly you have acquried the wrong vessel, personal opinion of course!
So anyone with a sunseeker Tomahawk 37 , princess 45, fairline turbo 36, er, Class 1 race boat... (i could go on!) and they all have trim tabs, has aquired the wrong vessel? or have i got the wrong end of the...
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Old 21 November 2006, 17:02   #19
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Quote:
Originally Posted by wavecrosschris View Post
So anyone with a sunseeker Tomahawk 37 , princess 45, fairline turbo 36, er, Class 1 race boat... (i could go on!) and they all have trim tabs, has aquired the wrong vessel? or have i got the wrong end of the...
What about Scorpion, they seem to put trim tabs on many of their ribs, they're one of the top rib manufacturers, surely they can't be wrong.

Freddie
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Old 21 November 2006, 17:04   #20
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What about Scorpion, they seem to put trim tabs on many of their ribs, they're one of the top rib manufacturers, surely they can't be wrong.

Freddie

funny, lol i was just looking at the scorprion website and couldn't see any tabs in the pics so didn't put them in my post - but knew the one that did the round britain must have had them!
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