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Low speed porpoise caused by step?

Old 07-10-2007, 03:15 PM
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Default Low speed porpoise caused by step?

Just bought a boat. The hull bottom is essentially the same as a Dana 23' open bow with one exception... mine was laid up with a step. I have a 454 magnum carb'd with a bravo 1 outdrive and bravo 1 22p prop. The prev owner had a "whale tail" on it for wakeboarding, etc. I pulled the whale tail off and picked up about 4 mph or so and a few hundred RPM. Boat runs great at high speed with the whale tail off but at around 30-35 mph it porpoises pretty bad, although I can get most of it out by trimming all the way in. It doesnt porpoise with the whale tail. I talked to one of the guys at Dana and they dont have the problem with the hull. They run the Bravo 1 22 and 24's on it with a bravo 1 drive.

I am going to check to make sure the hull doesnt have any rocker this weekend (boat is an hour away). I have a few questions in the meantime. Could the step be causing this? I figure with less of the back end in the water, there is less of the hull to push up and create stern lift (which the whale tail is compensating for). Could this be fixed with tabs? Was thinking about going with the Lencos for ease of installation although some eddies or danas look nice ($$$). I am thinking a more stern lifting prop isnt the right solution since the boat runs great at high speeds.
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Old 07-11-2007, 07:36 AM
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Yes I think the problem could be cured with trim tabs. I have a 23 Wellcraft nova, if the tabs are all the way up, she will bounce , but but the tabs down alittle and she smoths out.
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Old 07-11-2007, 08:44 AM
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I was pretty sure it could be cured with the tabs since the whale tail kinda covers up the problem. The question that I am most curious about is whether or not the step in the hull could be the reason for this.

Thanks
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Old 07-12-2007, 11:44 AM
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Nobody, huh?
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Old 07-13-2007, 08:56 AM
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Tabs will definitly help ALOT!
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