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Old 06-22-2016, 10:01 PM   #81
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Originally Posted by Nomad Willy View Post
Gordon,
Narrower FD boats respond better to paravane stabilizers.
Have you read my post #49 ?
Perhaps it's flawed.
If so how so?
Gordon isn't talking about paravanes. You keep reverting.
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Old 06-22-2016, 10:03 PM   #82
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Nomad Willy, why would I use paravanes when I can use hydraulic? I am not a nautical engineer and take no issue with your opinions.

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Old 06-22-2016, 10:06 PM   #83
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This short video of the OA 42's hull is quite revealing. The best look at the running hull is at the 1:45 mark of the video.]
Hmm. Walt,...I think I might have underestimated that hull. Of course, it's very calm water, but that baby is nicely trimmed. Anyway, I hate those videos that show glimpses of things and fade the frames "artistically" so you can never gain a point of reference on much of anything. Thankfully, they didn't do that to the shot underway before you could actually see something. Nice boat though.
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Old 06-23-2016, 06:08 AM   #84
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I don't buy it. I have seen G I G A N T I C planing boats with tremendous beam and interior space. Your boat is a perfect example. Your boat does not lack interior volume and it is not a semi planing hull. Ask Hargrave or whoever designed it. I would think it to be modified V.... Yes I know it is not cut and dry but Hatt has never been known for their semi hulls. In fact Your boat goes slower(15kts) simply due to a lack of power....not hull form. If your boat had 1500hp per side it would be perfectly happy cruising in the 20s. If you overpower a semi planing hull it will start to bow steer....IOW, all of the lift is in the aft part of the hull and the forward part has very little lift. This was an issue on the Mainship Pilot 2s with the 6 cylinder Yanmar...allegedly.
Sorry Baker but you are dead wrong about my boat. I got to compare its hull to a couple hundred other boats of all kinds during a couple of hurricane haul outs. Like the Fleming for instance it has a much fuller and deeper hull than boats the same size that can go twice as fast. Someday I will dig up the file of photos I took.

I may have a picture around of a Hatteras 58 LRC out of the water and the subtle difference between my hull and its.

My Hatteras achieved its very large interior via high freeboard and an 18'2" beam that extended for a good deal of the length. I have posted a picture of it next to a Fleming 55 that illustrates this dramatic above the water line difference. Another factor was that Hargrave molded the 1050 gallon fuel and 210 gallon holding tanks into the bottom center of the boat.
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Old 06-23-2016, 10:41 AM   #85
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Paravanes and fin stabilizers mechanically operated work the same way dynamicly so re this discussion are the same. They act as an ofset plane to the direction of movement. Offset when the boat rolls.

We actually have been arguing about the wrong thing. Re the effectiveness of stabilizers the question of FD or SD is mostly irrelevant.

One should say instead that boats w strong righting moments will find stabilizers less effective. Roughly speaking it's mostly the beam of a vessel that's the problem. SD or FD have little to do w it. Weight and inertia are involved in no small way too.

Imaging an unloaded barge w stabilizers. With this image anyone can see the stabs would be very ineffective. Then imagine a narrow, heavy and round bottomed boat w stabilizers. Very strong effect. The barge has an extremely strong righting moment and the narrow boat's righting moment is weak. I don't see where there's any room for discussion much less argument. Boats w a strong righting moment are not going to do as well w stabilizers ..... and that's just a fact as I see it.

For those not familar w the expression "righting moment" it's a force that tries to right a boat that is found to be tipped, rolled or otherwise (as they say) "not on an even keel". The rolling force that causes the boat to right itself. Of course when a boat is sideways on the face of a wave the boat (via it's righting moment) tends to right itself to the face of the wave. And the job of the stabilizers is to oppose this force so the boat won't jerk itself to a new and different position. "Snap roll". The stabilizers don't stabilize at all ... they just oppose the rate of movement to the tendency to roll.
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Old 06-23-2016, 10:52 AM   #86
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If I could post a short 39-second film, you would see how effective fin stabilizers are on my OA 456. Alas, I am unable to figure it out.

I understand you to say that the rounder, deeper hulls require more stabilization than SD hulls, and I think that is right. In the end, however, stabilizers make both hull types more comfortable, unless you like roll. I would have hated being on the Kady Krogen 48 without stabilizers.

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Old 06-23-2016, 11:08 AM   #87
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Dos'nt make it seaworthy.
Of course it doesn't since "seaworthy" is an insurance/legal term and not a marine term. "Seaworthy" defines the specific condition of a specific vessel for a specific voyage and includes a determination of the qualifications and competence of the master and crew for that specific voyage.
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Old 06-23-2016, 11:10 AM   #88
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Gordon,
You probably would'nt like my Willard. The only stabilizer I have is the substantial keel. But I would hate to think of the roll w/o the keel.
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Old 06-23-2016, 12:04 PM   #89
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if I were looking for smaller...

Quote:
Originally Posted by Nomad Willy View Post
Gordon,
You probably would'nt like my Willard. The only stabilizer I have is the substantial keel. But I would hate to think of the roll w/o the keel.
I am sure your boat would be fine. My OA 456 also has a keel, although not quite as large as yours (Proportionally), but still enough to reduce roll.

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