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Old 29 April 2005, 07:30   #1
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Trim Tabs on the cheap

Our Delta is still severely stern heavy, the 4 blade lower pitch prop helped with low down grunt but the heavy 100hp Yam still makes it bow up, next idea may be a doel fin lifting foil but I'm also looking for info on trim tabs. Did a search but couldnt find anythng on the more economic self adjusting ones any ideas anyone?
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Old 29 April 2005, 08:33   #2
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Simon Iím convinced that trim tabs and dol fins are only really covering problems you shouldnít be experiencing on a rib Trim tabs are great on a gin palace because it is harder to adjust the cargo, getting sun bathing beauties to Ďsit the boatí or balancing water or fuel tanks is hard so trim tabs solve the problem. On a rib you can move people and weights around to get the right trim and Iím convinced that this is what you should do it Trim tabs can have very strand effects, on a Nimbus 21 I used to use by playing with the tabs you could get the boat to almost lay on its side with a rib, that is primarily a safety boat, the last thing you want is something that has a negative effect on the handling and therefore safety So my advice is move the fuel tanks, move the anchor and even consider moving the console forwards to get the trim.
And as for dol fins have you got all day Des
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Old 29 April 2005, 08:56   #3
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We have almost exhausted the avenues of trim via repositioning of items, the console is as far frd as could be fitted so no joy there. When diving we had planned to put all weight belts in a box forward of the console also store spare fuel in this area too.

I saw a long doel fin thread a while back are you saying there is more...! Will also be requesting (when I helm the boat at least) that we have all the girls in bikinis up at the front too!...Hmmm

I think personally the engine is too heavy for the boat but that cannot be undone now. So as you said we are in a way masking an error.
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Old 29 April 2005, 09:01   #4
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Quote:
Originally Posted by Simon B
..........I think personally the engine is too heavy for the boat but that cannot be undone now.....................
I donít know, my brothers boat is a .5.5 ribcraft with a 115 (I think) on the back and that works fine but you do need to sit everyone parallel or forward of the console Where do you get people to sit Des
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Old 29 April 2005, 09:20   #5
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We still cant get it level even if we have everyone sat close up to the console on the tubes, this configuration is in my opinion a little dangerous as there have been times when people have absent mindedly grabbed the wheel and not a grab rail. Quite what would happen if they did the same with the throttle doesnt bear thinking about.

Additionally it can get a bit hairy when it starts to porpoise, this occurred last week on almost mirror finish water trimmed well in.
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Old 29 April 2005, 09:27   #6
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I wouldnt strictly agree that trim tabs are a panacea for poor design, layout, rigging etc as they are very useful for correcting lean into the wind on larger boats for example. I would agree that they should be unneccessary on a 5.5m RIB. In you circumstances I would try a doelfin as the cheaper option and a potential solution.
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Old 29 April 2005, 13:43   #7
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After much online research (search the forums on iboats.com), and Boatster's experience adding Nauticus Smart Tabs to his 4M Searider, I picked up a set on eBay for my 5.4M Searider. These are the self adjusting type you're speaking of. I fitted them prior to my first time using the boat, so I have no comparison, but I can attest to the fact that there is literally 0 bow lift and the boat jumps up onto the plane immediately. This is with myself, my wife and my 5 year old all seated on the standard jockey seat. You merely feel the boat accelerate as the ballast drains. I was very impressed. I am also able to keep the boat planing at what seemed to be a fairly low speed. BTW, Boatster is a huge convert, I recall seeing his posts on iboats railing against the Smart Tabs, now he loves them!

I want to experiment with the settings a bit and with them fully retracted as if they weren't there, but it's a low priority as my sailboat is to be launched on May 12th, with much to be done, plus my wife has all sorts of work for me to do in the garden! And I really need to clean and rebuild the carbs so the outboard will idle properly!

I read many negative things about doel fins, and removed the one that came with my outboard, in favor of the Smart Tabs. No offense to anyone opposed to adding tabs, but I really don't see any negatives, only benefits, So what's the problem? It was $90 well spent in my opinion.
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Old 29 April 2005, 17:51   #8
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Simon.

We have a Delta 5.5m as our main dive club RIB, fitted with a Mariner 90hp Fourstroke (which is a heavy lump). When out diving we have all the cylinders stored in the bow, weight belts down the side,and the rest of it in the stern. This gives us the best angle for the boat (sometimes bring a couple sets back to bring the nose up).

We have fitted doel fins/hydrofoils to the engine, and although I am not a fan of them, they have solved the problem of long time to plane and bow upness.

Hope this helps
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