Here are many proa layouts. Many of these are old designs and I am not happy with them. At the moment the top one would be my favourite. I have even more layouts. Many of these may not well work. The main intent is simply to get many designs out there to stimulate the mind. Thus many layouts are shown rather than a few refined designs
Below find some early drawings for a 56ft pacific proa. If I had more money that I could ever wish for, this is the boat I would build. Note the spars to windward and the way the rudders are protected by the large rocker of the hull. Looking at the diagrams now, many months after they were made, it is now obvious that the rudderboards need to be closer to the ends. This would ensure protection to the rudders on grounding by the rocker in the hull.
Below can be found some simple sketches for a 31ft proa. I think this is abuot the pure minimum that could be had for a comfortable cruising multihull. Small boats like the Wharram Tiki 21 which have been around the globe, yes they can do it, but not I think in comfort. I think this 31ft proa layout would be the pure minimum in terms of materials to build, being of a naturally lower structural weight than a catamaran of similar size.
Even lower can be seen a picture of Glen Tieman and his catamaran. From memory this is a Wharram design and Glenn is currently cruisng the Pacific. He built this boat for $14K, which is pretty amazing, I think he milled his own timber, thus the wood was in essence free.