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post #5806 of Old 01-23-2014 Thread Starter
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Design - Inverted bows

I have been talking about inverted bows on another thread but it is here that it makes sense to discuss them.

I will post some of the stuff I had posted elsewhere. They seem to me the next boat revolution after beam being brought back, resulting in large transoms even in not necessarily beamy boats.

No, they are not a fashion, they have a purpose and that's diminishing wave drag through a better wave penetration. Modern inverted bows were designed to meet strong sea conditions (with significant sized waves) and to be more efficient on those conditions. The inverted bow shape reduces pitch and speed loss in waves diminish slamming and bow impact, reducing stress in that area reducing the probability of damage in extreme weather..

An inverted bow does not result necessarily in a lower buoyancy at the bow. That depends of the bow design and it is possible to have a bigger buoyancy with a wave piercing bow than with a conventional one. The design would have to be a far more complex one but I believe that in the future we will see bows wit a rounded submersed shape, coming backwards and becoming thinner almost till the top where you have to add some kind of wingless to deflect and prevent the water to came rushing backwards. that will have also the advantage to create some lift.

Here, a motorboat with that type of deflectors I was imagining (it seems somebody has already invented it):

That way we can add the advantages of a rounded bow in what regards superior hull form stability and bigger buoyancy, specially needed with big transom boats going close upwind without, the disadvantages of a substantially increase wave drag (upwind) in difficult conditions.

Regarding offshore sailboats the inverted bows were first used on the new generation of racing multihulls namely the trimarans that were designed to beat the absolute solo circumnavigation record. You cannot do that with a sailboat that is not seaworthy since they will cross the worse seas on the planet. I am talking about Thomas Coville and Francis Joyon boats and they have done that successfully, at least Joyon. Coville is at the sea trying to beat Joyon circumnavigation record:

Since then all new built ocean racer trimarans were built with inverted bows:

Here the Prince de Bretagne:

Here Vibac Paprec:

Or here, Banque Populaire:

Many offshore cruising cats use already inverted bows:

and racing offshore monohulls start to use them too:

I bet that in less than two years a substantial number of offshore performance cruisers will be using them too, for a good reason: If well designed they are not a liability in what regards seaworthiness and improve performance. For now they are still very few. This is one of the first performance cruisers with an inverted bow, the beautiful and fast Neo 400:

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Last edited by PCP; 01-23-2014 at 07:16 PM.
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