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Old 27-12-2013, 10:14   #61
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Re: The Prout Debate

You'll have to give it up SS. I was thinking of the Wharrams . With the overhangs. Those U shape waterlines are also close to what you'd see on a wide canoe stern. There is nothing outdated about rounded V hulls, very seakindly and soft riding, this also makes them good for cruising tri amas.

All the tools of design are there to blend the chosen compromises in the best way possible for the intended use. Many compromises are currently selected which are marketing driven, this has led to more complicated shapes in an attempt to reduce the less than seaworthy aspects of these craft. Not often mentioned either is the center of gravity of these craft, let alone the center of pressure from the wind on these exposed topsides. Hard tops and flying bridges are raising the stakes in more ways than one. A boat that is overbuilt will also have a higher C of G, if the beam has not been increased it will be less stable than the designers intent. Naval architects are scrambling to try to keep these cruising demands within a certain safety margin but in no way are they necessarily safer than their predecessors. Because those older boats were keeping within the envelope, not over inflating the balloon, many have survived the test of time.
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Old 27-12-2013, 13:21   #62
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Re: The Prout Debate

Cav, I have to 'give it up'? You erroneously made the bald suggestion that double-enders have increased reserve bounyancy that is cut-off on boats with a transom; I merely pointed out that as your boat (a Prout, which is the topic of this thread afterall) has no rear overhangs, this is not even arguably true.

Yes, Wharrams have some rear overhang and therefore implicit in my statement is that one could at least argue about the increase in bouyancy as water rises up on the hulls from astern. Of course, the increase in bouyancy due to the overhangs would be much more gradual than the increase in bouyancy that occurs when a boat with U-shaped hulls aft and an elevated transom suddenly has the transom immersed in water!

I am not sure why you are talking about flying bridges, but we can agree that Prouts certainly don't have them (nor, I suspect, would any of the other cats that the OP would be considering in a similar price range).

I think that we can also agree that V (or 'modified' V shapes) are appropriate for the amas on a trimaran. Of course, the amas on a trimaran do not serve the same function as the hulls on a catamaran: they are intended to reduce heeling, reduce side-slip and in some cases, to provide lift. They are not typically intended to carry load or weight apart from that induced on the leeward side by heeling forces.

Remember, I am not 'anti-Prout'. I have already expressed the opinion in post 43 that early Prouts are excellent sea boats. In the same post I also extolled the virtues of the low freeboard, Ce for the sailplan and Cg of the hull. I even commended the 'Prout', or cutter rig for a cruising cat. Where we differ on the question of the early Prouts is with respect to the efficacy of their double-ended hulls. I think we have just about beaten that topic to death and others can read our respective arguments and, if they so choose, do some additional research on such things as bouyancy, hobby-horsing, wetted surface, prismatic coefficient and the load carrying ability of modified V shaped, double-ended hulls versus U-shaped hulls with transoms.

Brad

PS Just so that my silence is not taken as tacit approval, I suspect that we also differ on the beneifts of the solid foredeck, low bridgedeck clearance and extremely low, central pods for a single diesel on some Prouts, but we can leave that for another day. Thanks for the spirited debate!
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Old 27-12-2013, 16:01   #63
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Re: The Prout Debate

I thought I made it clear that my point was double enders CAN have superior buoyancy aft. So I must insist the errors are in your understanding!

We could touch on those other things....there is a lot of merit for keeping the windage down. Your average double ended Prout can keep bumping to windward at a close angle in winds that the tall boys can't buck into. While I'd prefer not to have the solid deck forward they are useful in several ways. 1 ease of working on deck 2 less spray on deck. 3 excellent endplate effect for the genoa.4 much stronger bows. All good for the cruiser.....downside? More bumps from the waves. I don't think pitching is increased much because they act like an air damper. There is a reason we call wing decks air compressors...because they do.

Cheers!
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Old 27-12-2013, 16:05   #64
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Re: The Prout Debate

Off topic but those tri amas do wind up carrying most of the load of the boat as the wind picks up and heeling forces increase....A softer ride in both 2 and 3 hull configurations mean less strain on the structure and the crew.
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