Catamaran and trimaran boat plans make it a reality to build your own catamaran or trimaran. multi-hulled sailing vessels are a special class of boat. a very different mind set is required when thinking about sailing a multi hull, let alone getting your head around building one.. The boats were elegant and reasonably simple to build and 1000s of sets of plans were sold worldwide; every creek you went to there was a wharram. james and hanneke are still designing catamarans and many are still being built around the world.. These plywood power catamaran boat plans help you construct this modern catamaran for twin outboards. buy power catamaran boat plans & more at bateau.com! of pages of tutorials, plans updates, a forum to share ideas about our boats and thousands of pictures – see completed boats and many of the building steps done by builders like you. all.