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Question about planing devices

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Old 01-12-2011, 09:58 AM
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Default Question about planing devices

I picked up a 221 Liberator at the end of the boating season last year and only used it a couple of times. It has a 468 Chevy and King Cobra outdrive. The previous owner installed a large fin on the drive to get it to plane quicker for skiing with his kids. The boat comes up on plane very quickly. I don't use the boat for skiing. Does the fin detract from the boats higher speed performance?
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Old 01-12-2011, 10:07 AM
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Ditch the fin and install trim tabs if planning becomes an issue. You can use Marine Tex to fill the holes on the outdrive.
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Old 01-12-2011, 10:28 AM
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I am not sure I agree. Tabs would be better for sure, but drag race outboard boats all use planning fins on the drive. At higher speed they are completley out of the water and I do not think they would slow you down at all. I think a small boat like a 22' it would not be a problem.
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Old 01-12-2011, 10:33 AM
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You have a 22' boat with a 468 CID Chevy and it needs a planing aid? I don't think so. Take it off now before anyone else sees it.
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Old 01-12-2011, 11:13 AM
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If you don't plan on using the boat for any water sports I would ditch it. The purpose is to get the boat on plane faster and keep it on plane at slower speeds for skiers.

I don't think it would negatively effect the performance, though.
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Old 01-12-2011, 11:40 AM
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Quote:
Originally Posted by 3birds View Post
I picked up a 221 Liberator at the end of the boating season last year and only used it a couple of times. It has a 468 Chevy and King Cobra outdrive. The previous owner installed a large fin on the drive to get it to plane quicker for skiing with his kids. The boat comes up on plane very quickly. I don't use the boat for skiing. Does the fin detract from the boats higher speed performance?
Run it, remove the 4 bolts to remove the fin, do a back to back test run.
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Old 01-12-2011, 11:41 AM
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I am not sure I agree. Tabs would be better for sure, but drag race outboard boats all use planning fins on the drive. At higher speed they are completley out of the water and I do not think they would slow you down at all. I think a small boat like a 22' it would not be a problem.
Agree it should not affect high speed performance. I just hate seeing these things on any boat. I should have stated such.
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Old 01-12-2011, 11:45 AM
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It will actually scrub about 2-3 mph off on top speed and they exert huge forces on the cavitation plate and cause them to break. O your boat with that much power you may not see as much of a speed drop, but on a 40-50 mph I have seen as much as 3 mph more with it off. And of course having the cavitation plate welded back on is always a joy too

Lose it, you'll be happy. Fill the holes with Marinetex or epoxy as someone else said.
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Old 01-13-2011, 09:07 AM
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I'll pull it off and fill the holes. Worse case is to put it back on if needed. I also think I can go a larger prop.
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Old 01-13-2011, 10:26 AM
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I'll pull it off and fill the holes. Worse case is to put it back on if needed. I also think I can go a larger prop.
Good call. Those things belong on 4 banger Bayliners and such that can't get on plane without some help! You can always have two props; A power prop and a top end prop.
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