This morning I saw him again and realized I had enough time for a quick look at his boat. We walked over and he explained that his boat has been out of the water for some time while he is working on it. Sure enough there it was in the lot, a big catamaran designed by James Wharram (http://wharram.com/index.php). He told me he built her out of 9 mm marine plywood. This is just 3/8" which sounds pretty light to me for a boat this size.
What really amazed me, and if he hadn't pointed it out I would have never noticed, is that he took off his rudder hardware and replaced the gudgeons and pintles with lashings! He said that this was a suggestion from a friend in Kagoshima, a place he stayed in transit to here from Osaka, where he built the boat. He and his friend were inspired by the sailors of Polynesia in making this change. The rudders swung kind of stiffly on the lashings, but he assured me that he had complete confidence in this arrangement. Of course if they showed signs of wear they'd be simple and inexpensive to replace. Four lashings hold each rudder. What an idea!