10' Class Proa

Thoughts about a cheap and simple to build proa for the 10' class. The main hull (Vaka) has flat bottom like a dory to support the lift of the crab claw sail during high speed. The body of the main hull is very wide to get the necessary buoyancy for boat and skipper. The behavior will be a little bit like a thick surfboard. Nevertheless is the seat for the sailor comfortable by the little cockpit for his feet. The outrigger carries only about 30-40 kg on his leverarm until it submersed. The whole displacement should be at 130-140 kg. The prismatic coefficient is 0,65.

The sail area with about 6,0 square meter corresponds nearly to 8-9 sqm of a classic bermuda rig. The Crab Claw is running on a rail which is fixed on both bow sprits and the beams. Alternative a Dierking/Gibbons rig is possible in the same way it is used at my 5m design P5. The Crab Claw may have advantages in wind beam reach, the Gibbons may be better close to the wind and have an easier handling during shunting. For all beginners: animated example of shunting.

P3 at the Nautex in Rimini 2002 by Mario Marti P3 built in South Africa by Rod Gauld

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P3: Gibbons/Dierking with 6,0 sqm

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P3: Crab Claw with 6,0 sqm

In the following I offer a few drawings for all interested people which are crazy enough to build such a boat to take part in the 10' class regattas. Be shure that nothing is perfect and all measurements will be handled with care. In every case a lot of creativity in detail are required - please have a look at the comments at the end of the page (click on thumbnail to enlarge plans):

Cutplan - 2-3 sheets of playwood

Vaka - main hull

Ama - Outrigger

Top view


Mast support variants

Leeboard variant

Bowsprit variants

Some comments for building the P3

I know the support is not dazzling (independent from my awful English), but the P3 is at last a experimental platform, which gives everybody a lot of freedom to realize things by himself. So don't worry be happy.

Othmar Karschulin

A nice building report

I found your plans for the 10' class proa and decided to build it this past summer. I have no experience in building boats before. Your instructions were very helpful in guiding me to a sailable boat.
I put together a galley of my experience with the build at https://imgur.com/a/dgiv0qE
Thank you for the boat plan. I learned a lot making the boat. This is the first of many sailboats I will build.
Thomas Murphy, Toronto, Canada

For further information to the big sister of the P3 see the description
of the 5 m proa P5
And at last will try to answer all the Questions you may have ...

 Othmar Karschulin