Hi from Southampton
Im student in yacht design at Southampton Solent university,
A proa design is going to be my final year project, lot of things to think about,
so I guess you will all be a big help for me this year !
Thanks to all for that !

Welcome to the forum.  Looking forward to seeing your work!

Best,
chris

Great choice of project! What type of size will this be, and will it be built?

Also, here’s someone else who did a proa as their final year project in NZ:
http://www.brettmarinedesign.com/

Cheers,
Thomas

Great to see someone in the UK interested in proa’s. Look forward to hearing what you have planned

Tink (up in the North East (England))

Hi
The proa should be around 8m long, built in plywood and epxoy…Well at this moment this is the N°1 option though Im considering a few other ones.
Here is an idea of what the main hull should look like. It seems to me that generally the main hull tends to be narrower, but my goal is to get a bit closer of the planning mode. What do you think ?
Of course the hull is asymetric (larger side on windward), to create lift on windward. I should be able to proove its efficiency with some tank testing…

matthieu - 21 October 2013 02:29 AM

It seems to me that generally the main hull tends to be narrower, but my goal is to get a bit closer of the planning mode. What do you think ?

A two-way planing hull is likely to be difficult, at least for as long as you have a rig that depresses the bow.  If your rig lifts the bow, then it can be done, as Dave Culp proved with his kite-powered Whigmaleerie (http://www.dcss.org/speedsl/).  If I remember correctly, he described the boat in the last issue of Kitesailing International, at the bottom of the page.

I recommend Bernard Smith’s book “Sailloons and Fliptackers for some unorthodox designs, apparently developed by throwing out all conventions, reducing the problem to the very basics, then building again from the ground up.  The man was a genius.  A summary of his work is at http://www.geocities.com/aerohydro/home.htm.  some follow-up has been here: http://www.sailblogs.com/member/speedtech/.  I haven’t noticed any further design development for a while, though.

matthieu - 21 October 2013 02:29 AM

Of course the hull is asymetric (larger side on windward), to create lift on windward. I should be able to proove its efficiency with some tank testing…

Welcome.

I look forward to seeing the results of a tank test, but I am extremely skeptical of the ability of a round bottom hull to generate any meaningful lift to windward.  Any hull, as a very low aspect ratio foil, will create some lift to windward and an asymmetric hull, as a very low aspect ratio cambered foil, will generate more lift at a given leeway angle.  But the problem with low aspect ratio foils is that spanwise flow will greatly diminish any lift they might create, and the problem with a round bottom hull is that it has almost no resistance to spanwise flow.  The asymmetry works well in Micronesian style hull forms because the very deep V helps to limit spanwise flow, but with a round bottom I just don’t see any point to asymmetry as all of your lift will be generated by a fin or a lee or dagger board either way.  By all means try it and see, but I’m quite sure you’ll be disappointed with the results.

Matthieu, Ralph Munroe built four planing proas back in 1898-1900. They were about 30 feet long, and the hulls were a flat-bottomed sharpie type about 2.5 to 3 feet beam at the sheer. Centerboards up, the boats drew about 5-6 inches with about the same amount of rocker, and in terms of construction and design were dead simple.  This might make a good starting point for your design if you are interested in getting the boat to plane; in general, I am a bit surprised that more experimenters don’t start from these boats.

http://www.thecheappages.com/proa/commodore.html#1898

From the Vincent Gilpin piece:

“I have postponed mention of one very interesting sideline in the Commodore’s drawing room—namely, the “flying proas.” ...

“... They found themselves across the Bay in no time, and the next question was, what would she do running free?
...
“With the growing wind on the quarter, outrigger in air and spray flying, they were traveling at a very high speed for a small boat. Then suddenly, with a little extra puff, the fore part of the boat lifted under them and, skimming the surface like a skipping stone, leaped into a surprising burst of speed. The sea beneath swept by like a cataract, vague and foam-streaked, the tugging steering oar cut a clear open cleft in the water and threw up on either side a long rainbow of spray, while the boat itself rested so lightly on the water that she made little, if any, disturbance in her flight.
...
“The facts are that the proa, though it had the limitations of an ordinary boat when sailed close to the wind quite literally took wings after slacking off even a small portion of the sheet. Except when close-hauled by the wind, the outrigger proved entirely unnecessary and no excess of wind had any other effect in her except to make her go faster and faster with her bow literally soaring in air. Her limit was never reached even in the hardest summer squalls, and it is probable that the only limit that would ever handicap her would be the limit of the steersman’s power.”