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trim tabs or doel fins ///


bacon100
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Hi Bacon

 

Welcome to Poole Bay.

 

Do you have a picture of your boat?

Assuming she is a planing through to semi planing hull then I think you have a more fendamental issue if you are not get up with 130Hp in 21 feet.

That's bags of Hp to pop you up and fly you along.

 

Trim tabs may give a marginal boost to get you up, but that is not their purpose. They will give a hell of an improved ride once you learn to use them effectively in different sea conditions.

 

Once again welcome and post a pic we'll see if we can help.

 

Tom

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Hi Darrell

 

Welcome to the forum

 

Would love to have a chat with you sometime about Volvo leg's. Have a similar one to you by the looks of it, mine is a AP275.

What size prop have you managed to work it out to?

I am running a 15x19 but I think this is too high and was thinking along the 15x17 or 15x15 to allow the revs to get up. I am running a Ford 2.5ltr desiel turbo.

 

To get back to the thread, if you want to have a look at the Eltrim Trim tabs on my boat give me a shout.

 

user posted image

 

user posted image

 

Coddy

cool.gif

Edited by Coddy
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From the back, the underwater profile look about the same as mine.

What's the displacement? About 1.5 tonne at a guess, which would be about 86hp per tonne.

 

Less than 50hp per tonne planning will be difficult, at 64hp per tonne planning should be easy, so unless she displaces more than 2 tonnes she should plane easily.

 

1. Is your engine running right?

2. Are you getting max revs?

3. Is all the weight at the back?

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HI thanks for all the replys ,first if you click on the photo it will give you a look at the front and side , it is runing fine now after a top end rebuild. Its a aq130 on a 270 drive with 2.15 gearing At the moment its got a 14.5 * 13 prop and reves out to quick so will go back to the 15*15 it came with all though it still wouldn,t plane its so close but the back just seams to squat down to much.I think maybe your right Brain its got all the weight over the back. Im told its around the 2 ton mark .Im working away this week so will not get to see the replys till friday but thanks again and I look forward to days out meeting some of you out there .Darrell

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Nic semi displacement hull, but it does look like it might prefer a shaft drive over an outdrive and so it could well be weight distribution.

I take it you have the leg trimmed right in when you hit the throttle?

Tabs may well help you get out of the water a little quicker, but that HP should have no issues getting you up and running.

Is the engine definitely getting it's Hp?

 

Tom

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  • 3 months later...

Hi,

 

Just to bring this back to the top as Darrell is still having trouble with planing......

 

We were out playing with the prop/whale tail and engine trim over the weekend and nothing we did made much difference. We have tried hanging two large people over the front and even that didn't pop it onto the plane!

 

Current symptoms:

 

Engine trimmed in to max (pin placed in closest hole to transom)

Engine revs to 4200rpm when excelerating in gear, front bow rises, rear squats and that is it! It feels as though the engine still needs to be trimmed in some more but there is no movement left.

 

All appears to be original so if it should plane everything appears to be as it should be.

 

We did get it to rev to 4600rpm at max revs with two people hanging of the bow but it was no nearer to planing.....

 

As we are making peak revs at full throttle we are really not sure where to go from here, any suggestions?

 

Cheers,

 

Darren.

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As I said before your hull looks identical to mine.

Sounds to be behaving that same as my boat was before I fitted Bennett trim Tabs.

She was lifting the bow and squatting at the stern, due to all the weight being at the back.

After fitting 18" x 12" trim tabs she leveled off and planned. I bought mine from Magic Marine at Broadstone.

 

Due to rot in the internal timber I've advertised my boat as a renovation project, if it doesn't sell in a couple of weeks I'll be stripping everything off and selling the bits, so might have a set of Bennett tabs going cheap.

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making some temporary trim tabs

 

wink.gifwink.gif How?? This sounds dodgy... do you mean temporary doel fins? If you mean temp trim tabs, how will you do that?

 

Persoanlly, I'd suggest a power issue, as 130hp should be more than enough to plane the boat - unless it is heavier than it should be, i.e water logged, and than tabs will be a temp cure, and not really solving the main problem.... Its hard to tell over the internet.

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Coddy and trever good to meet up over the weekend, the out come is that the doelfins do seem to lift the stern; but the bow is still pointing up to the sky .trim tabs are now on order. trev the 15x15 you lent me will only get 3200-3400 rpm and i pulled 4200-4400 with a 16x13 so im going to get the pitch checked if thats ok ,maybe its been re done at some time because that does not add up to me . Thanks again for your help ill let you no the outcome Darrell

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  • 3 weeks later...

As you have looked at this from all other angles what about checking out the turbo to ensure that you are getting the full boost pressure. Just because you can pull max revs with an egg whisk doesn't necessarily mean you are getting full power from your unit. If your not getting full pressure then the engine will not turn an adequately sized propeller to give you the performance you need/should have

 

Just a thought

 

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