Plane a double ender

[DrCraze]

I have given this much thought as well. My thinking is flush mounted trim tabs at each bow to act as phantom transoms. "Phantom Transom" thats what we should call them.

[DrCraze]

Seeing as you have light winds I would advise building a lee deck to counter the weight of the ama. It is what hundreds of years of R & D has come up with so give it a try.

[hoytedow]

Here is a very interesting article on proas including the lee deck mentioned by Dr. Craze.:
http://www.wingo.com/proa/micronesia...e_Islands.html

[Inquisitor]

Oh! Now it makes sense... about the lee deck.

I'm quite enammered with the HarryProa design. It just makes better sense to me...

It makes the alma the primary sailing hull and the living quarters (a lot heavier) the counter weight for the heeling. Basically you have the leverage of a trimaran when it is flying two hulls without having to carry all the extra structure and extra alma. So, in theory, I'm thinking, it should out run trimarans of similar size.

[hoytedow]

Probably so, but the correct word is ama, Get the l out of there.

[HakimKlunker]

Originally Posted by Inquisitor

Is it possible to make a symmetric hull (front to back symmetry) that will plane or is the blunt transom required? In other words could a boat plane going forward and backwards?

If you really intend to plane in reverse, please let me know when and where - - - so that I can be very far away from there

[daiquiri]

Originally Posted by Inquisitor

Is it possible to make a symmetric hull (front to back symmetry) that will plane or is the blunt transom required? In other words could a boat plane going forward and backwards?

If we are talking about a powerboat, then the short answer is - yes, it can. But it has to meet several requirements:
- it has to be light enough
- it needs a little add-on at the transom.

An example comes. This is a "gozzo", a very popular traditional boat of the mediterranean area:



It is a double-ender, a pure displacement boat, originally equipped with latin sails. With the advent of IC engines, the sails were substituted with slow-reving inboard diesels (I can still remember waking up as a child with that relaxing "-pom-pom-pom-pom-pom-pom-" sound coming from the sea ), and later with fast diesels too.

The latter engines, together with this modification at the transom (the first photo shows an add-on, the second one a design hull feature) alowed it to go beyond the "hull speed":



though not so efficiently as a prismatic hull can (obviously). But again, the hull needs to be of lightweight construction - even a transom plate can do very little (or nothing) to help a heavy hull go over the hump.

Finally, this is what a modern GRP gozzo looks like at full speed:



I hope the photos are not too big for your screens. I wanted them a bit bigger to show all the details of this beautiful boat type. I really like the gozzo shape. Or maybe it's just a matter of memories from the childhood.