Patterson Trimaran

The following text and photographs are from a thread on boatdesign dot net. Specifically under the multihull section in the forums, then go to multihull structure thought. Please not that at time of writing the thread is over 205 pages and growing. The reason for copying the post here is that it is hard work for people to go through 205 pages of forums just to find specific information on one boat. The link to the page in question in here LINK


This is an update on Little Boat a John Patterson design that is much admired (page 83 Multihull Structure Thoughts). The ”Little Boat” is 21 x 16 foot and can be folded to 8 foot wide for trailing. John made a statement that the tri weighs about 500 lbs, a number I doubt, the displacement is approximately 1600 lbs based on the main hull plan in the jpeg. The reason I doubt the weight figure is a Corsair Pulse 600 racing tri weighs 990 lbs with a displacement of about 1600 lbs. The wing mast of the “Little Boat” is 27.5 foot high with approximately 160 square foot main and wing and 95 square foot foretriangle. A kick up spade rudder, daggerboard, and wing mast made for performance up wind or down. The tri is fully trailable.

The main hull length to beam is 9.5 to 1. John designed his larger tri’s with 200% buoyancy in the floats. I am assuming a similar floats ratio based on the jpegs. “Little Boat” had a porta-potty under a single berth forward, small galley, centre cockpit, and an optimistic “double” berth aft. The maximum head room is 4.25 foot. John lived aboard for over four months at one time as he cruised around the Caribbean. According to John, Little Boat is capable of offshore sailing if required and he feels safe in strong winds with just the wing mast and a drogue in difficult conditions. According to John Patterson can handle 40 knot plus wind conditions (not sailing just towing an anchor drogue).

As you can see from the jpegs Little Boat is constructed from strip plank cedar with e-glass epoxy inside and out with plywood internals and deck . There are 4 plywood bulkheads. The crossarm structure is a combination of strip plank cedar e-glass epoxy, solid timber lower support straps and metal hinge straps. The setup was complicated and hard to build. It was a variation of Farriers but at the time it was designed Farriers patents were still in force. The cross arm structure could now be simplified as farriers patents are no longer in force.

The hull line jpeg is the actual hull lines of the main hull of the 21 foot tri. The lines give you enough to develop your own version if you have the desire.. If anyone has a set of plans please advise as John Patterson has said they can be published but no build support will be provided.

The jpegs are of 1 of the only 3 known Patterson 21’s in existence. From the limited reports this is a very good tri that is a fast cruiser for 1 or 2 that has limited offshore capability. The only issue would be payload. This is a very attractive and practical boat.

The following is a quote from John about Little Boat. “Some of my most enjoyable sailing was on my smallest tris. I no longer want to sell plans as I am usually on the move cruising on my 44-tri in the West Indies or visiting family in Mexico and I don’t feel I could give good follow up for builders. The boat in question was 21-ft by 16-ft and folded to 8ft for trailering. I sailed it over 2,000 Great Lakes miles, 6,000 ocean miles and 15,000 road miles. It had a porta-potty under a single berth forward, small galley, center cockpit, and double berth aft. I lived aboard for over four months one time. A kick up spade rudder, daggerboard, and wing mast made for great performance up wind or down.

Three were built that I know of — one by me — but there could have been more as I think the plans got passed around (I hope). There is only one photo of it at my old website, PattersonYachts.com, as at the time I was trying to do larger boats before I retired.”

A quote from the next owner. “I bought “Little Boat” from John Patterson. That is me sailing in the pic’s. This was an amazing little boat. Ceder strip built beautifully. Aft cabin really a single but comfortable. I know john sailed her in the keys for 6 months. Had a head and tiny galley. Wing mast was great and rudder system worked very well. As I sail mainly in light air I wish the stick would have been 34′ instead of 29′. Very stable boat to sail and easy to trail.”