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The Ulua and Tamanu sailing canoes, which are based upon Polynesian outriggers, can both be set up as very capable small trimarans. These models are creations of boat designer Gary Dierking, who is known for boats that are both efficient and cost effective. In other words, Gary’s designs offer “a big bang for the buck.”

Sailor and homebuilder Dan St. Gean has built both of them. He has sailed the Ulua as a trimaran and he built 2 Tamanu hulls in order to set up a versatile catamaran. (He is going to set up one of these hulls as a Tamanu trimaran this coming year). I asked him if he’d share a little about his background — and these 2 models in particular — with readers this month. He kindly wrote the following for us. (Many thanks Dan)!

Ulua & Tamanu

I got into sailing first by taking a trip from Cabo San Lucas to my home in San Diego aboard a 49′ sloop owned by a business friend of my father’s. My goal was to surf the point breaks along the way, but the friend was more concerned with washing down the boat between anchorages. I also nearly got blown out to sea with a fierce offshore/sideshore wind after a surf session! Not having any nearby boats after that trip really ended any real interest for a while. Surfing in Encinitas was easy–finding a ride down to San Diego harbor, even during the America’s Cup was not.

After college in the midwest, my father in law decided to sign up for a learn to sail course in Captiva, FL. That got my interest in a big way, but also cured me from wanting keelboats. Yeah, like every other boater in SW Florida, I ran aground … on a falling tide, in 20 knots of wind blowing the water out of the bay, with a plane to catch in a couple hours. I’m sure the Colegate school loved me for that one!

I wanted a versatile boat that could both paddle two and sail. That limited me to sailing canoes at the time. I found some great information about HSCA outriggers online and the really cool Holopuni sailing canoe as well. There wasn’t much else available at the time for homebuilders. Then Gary Dierking decided to publish plans for his Ulua. The only other plan set available was the plywood Selway-Fisher design, but I wasn’t as excited about the looks. I bought the plans for the canoe thinking I could cartop it and use it at the cottage in WI or on my local river as a paddling boat. I loved the looks and versatility of the design. I came from a paddling and surfing background, so the canoe form was very appealing.


I think building a Ulua is a bit time consuming, but no more so than a stripper canoe. Adding the outriggers, iakos, sailing bits, mast, etc ups the time factor quite a bit. It’s a beautiful boat that never fails to attract attention. I stretched the design, which Gary is fine with, to 21′. Several others have been built up to 27′ on the same plan set. I also stretched the stem and stern out proportionately, but wouldn’t do so again–In fact, Gary now recommends against that, instead spacing the remaining forms to achieve the additional length. I also had a had a hard time shaping the foam amas. Surfboard shapers have new respect in my book!


My usage of the boat as a trimaran suffered from perhaps a premature launch. I had not finished the rudder and had to paddle steer initially. Huge props to the guys who like that, but I prefer to sit centered rather than all the way aft. Additionally, paddle steering is a two handed affair, so singlehanding was a three handed affair. My logic was also twisted by sailing a Hobie Wave with its underpowered 98 square foot sail. I thought a boat 8′ longer might be able to stand up to more sail than the diminutive Wave. That’s almost double the SA that Gary recommends … anyhow, in anything over about 10-12 knots of wind, the hull flexed somewhat alarmingly with it’s freestanding 21′ long rig. Going to a reefed position remedied that, and at 80 square feet is pretty close to what Gary recommends.
Imagine that! Like many other Hawaiian canoes, I find the iako needs to be spaced
up a bit to get the boat heeled over a bit.


Sailing in motorboat wakes tends to make the more upright posture to want to slap back and forth from ama to ama. More to the point, I overbuilt both iako on the racing recommendation of the DGS guys racing in the HSCA. That, and my overweight mast (not to mention my overweight butt) conspired to leave little freeboard. I thought of decking the boat to eliminate the swamping possibility, but I went on a diet (and so did the boat). Adding to any design is a recipe for trouble–especially with a hack knowledge base! Gary was patient with me though and helped guide me through the process.

I’m really happy with my Ulua now as I can sail her as a single outrigger or a tri! Like many low volume ama designs, the boat will bury an ama before attempting to lift the central hull. I’m fine with that, but do wish I had gone higher volume as docking a boat with a low volume ama and 7′ to the dock leads to some speedy scurrying or wet legs! I love the way the boat slices through the water and the tramps on both sides really extend the usability of the design in my opinion. This Ulua is really a hodgepodge compared to building exactly to Gary’s beautiful plans. I thought stretching it and adding sail was a great idea at the time … all the mistakes have been mine, but I learned a lot and am happy to have proceeded as I have. I don’t know if I would take mine on a trip like Tim Anderson did, but am more than happy with it’s performance overall.

Like most Hawaiian canoes, it is loose to paddle rather than tracking straight. Leaving the tiller extension under my thigh remedies that, and that same looseness is a joy when sailing! I think it’s a great beach boat, a fun solo adventure craft at 18-21′, and is hugely adaptable. Buying a used beach cat is always cheaper in the long run and an easier way to achieve performance, but not everyone is into that — hence the Small Tri Guy phenomenon.

Tamanu Hull Under Construction

Tamanu Hull Under Construction

I decided to build Gary’s Tamanu as well since many of my Ulua parts are interchangeable. Additionally the decked option eliminated any fears of swamping. Moreover, I wanted a boat I could use as a two up paddling outrigger, a sailing outrigger, a trimaran cruiser for one (or two), and a hull that could be used as a catamaran for expeditions. That’s a lot for one hull to do, but I liked the decked Tamanu for a couple reasons such as being decked with self bailing footwells.

2 Tamanu Hulls Set Up as a Catamaran

2 Tamanu Hulls Set Up as a Catamaran

I’ve already taken it on a pretty extensive shakedown–the Texas 200 in catamaran mode and am impressed so far! I’ll be working on the single outrigger and tri version this Winter and Spring. It looks to be a capable design. — Dan St. Gean

Dan has also contributed articles to Duckworks Magazine about his boats …

Click here for more on his outrigger adventures.

And click here to read more about his fun with outriggers.