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by Frank Smoot - Florida - USA

“One Boat, Two Seats, Three Hulls - and Four Sail Plans?”

You know, building a sail boat can be a true delight. But it can also be a real challenge and a major learning experience. Building a boat that is your own design multiplies that challenge dramatically.

And if it’s a trimaran you’re designing and building, the number of opportunities to screw something up is multiplied several times over. And if you build your boats like I do (as light as humanly possible) the biggest challenge is to keep something really important from breaking at an incredibly inconvenient time and place – like several miles from your launch point in 15-20 mph of wind.


One of the biggest areas of challenge for DIY sailboat designer/builders is choosing the right sail rig. Not that any single rig is “perfect” for a particular boat, but ideally, your sail plan needs to be:

  • big enough to give you the speed you want;
  • simple enough to both rig and operate that sailing is more fun than work;
  • sturdy enough that it won’t break and leave you stranded (or worse);
  • and well balanced enough that you won’t have to be constantly battling your rudder.

How do I know all of this is true? Because, after having built a dozen or so boats of my own design, I think I have made just about every possible mistake in both design and construction – including having the mast step blow out through the bottom of the hull at 14 mph, resulting in both very rapid deceleration and an almost equally rapid rise of water level in the main hull. (Thank heaven it was a trimaran, or it would have sunk like a stone.)

All of this brings me to introduce to you my latest trimaran creation: a 19-footer with a 14’ maximum beam and 18’ outriggers, or “amas” (as we trimariners like to call them). Here are a few late-stage construction photos that show just how lightly built this boat is.

The hull is of stitch and glue construction, but not the way most folks do it. First, I used el cheapo 3mm lauan plywood everywhere – deck, side, bottom. Why? Because I have found that it’s stiffer and sturdier than the “gold standard,” AKA 3mm okoume. It’s also WAY cheaper (about $12 a sheet), and despite all them negative comments people so often make, it has never delaminated no matter how wet it got, or for how long.

And instead of going the epoxy fillet/glass tape route, I just used two layers of PL Premium polyurethane construction adhesive to attach all the panel edges. And instead of covering my boat inside and out with fiberglass and epoxy, I just apply a single layer of 6-ounce glass on the outside of the hull, and go with 4 oz on the deck and amas. I have been building this way since my first boats, and I can tell you with confidence that it’s plenty strong enough for anything short of a blue-water cruiser.

Now, I had always heard that trimarans don’t point as well as monohulls. But you know what? It all depends on the trimaran! And I’m delighted to report that this little trimaran has outpointed every other boat I’ve sailed or sailed with – be it monohull, cat, or tri.

I think there are two reasons for its great upwind performance. One, it has (fortunately) turned out to be perfectly balanced, with the result that virtually zero rudder effort is required on any point of sail. Two, it has a LOT of lateral resistance available, in the form of twin leeboards. Together, these leeboards give me about 5 sq ft of lateral resistance – enough to allow this boat to make 8 mph when pointing 45 degrees off the wind in 15 mph of wind.

And the rudder is very big as well, which also makes a contribution to lateral resistance. But because we have quite a bit of shoal water in these parts, the rudder is shaped more like an axe head than a dagger. It’s also 100% remotely operable; you can lower it fully or raise it 180 degrees from the cockpit.

Of course, this is really a necessity in a boat where you can’t get to the transom. But it sure is convenient, and the rudder can also be “locked” in the down position with one of Duckwork’s very cool cleats that automatically pop open when the rudder hits the bottom or any other obstruction. And a big added benefit of this design is that NO lead weights are needed in the rudder to hold it down (and none in the leeboards, for that matter).

One aspect of this trimaran design that is (as far as I know) unique, is that it has a sliding “main” seat that allows the boat to be perfectly balanced whether sailing solo or with a friend. This was not the easiest thing in a boat with foot-pedal steering, so I had to devise a sliding seat on a track that also included the steering pedals.

 This way I can actually sit in one of three positions, each being 16” apart, and still have the foot pedals at the ideal distance from my forward-facing seat. When sailing alone, the seat is in the middle position. When I have company, my seat slides forward and the passenger sits in a removable seat behind me.

Cockpit & seat

Over the years, I have tried a dozen or so different ama designs. The ones you see here are 18’ long, weigh just 32 lbs apiece, and have sharp V-bottoms. I could write a whole article on why I believe this design is optimal, but for now I’ll just say that they are perfect for this boat. They are quiet, smooth-riding, slippery, and never splash me, yet provide so much buoyancy that they have never even been submerged up to the chine. And I have to say, one of my favorite things about this boat is being able to watch these long, slender amas slice cleanly through the water and waves at up to 14 mph.

The amas

OK, enough about the whys and wherefores of construction. Now we can talk about the real issue at hand and the focus of this article: How in the heck does one boat end up with four different sail plans and rigs?

The short answer is…trial and error (with a lots and lots of error). Here’s what I started with:

I was really eager to see what the boat looked like fully assembled, so I put all the pieces together in my front yard. The akas (crosstubes) are simple 12’ long, 3” diameter pieces of tubing attached to both main hull and amas via bolts and knurled knobs. Simple, lightweight, and easy to assemble. The mast is also made of stock tubing.

I took the boat out just the way you see it in the first photo, in 15-20 mph of wind, and hit 14 mph 1st time out. It’s probably gone faster than that with the bigger sail rigs, but I keep forgetting to bring my Garmin.

This photo, the bow shot with the white sail, shows one of my homemade “fan sails,” a design I may have invented. (Probably not, but I’ve never seen another one.) This one is about 118 sq ft, and works very well on all points of sail.

The sail is assembled just like a fan, with four battens radiating out from the tack. It’s laced to the boom at the foot and to a “luff spar” which more or less becomes the mast when hoisted vertical by a halyard attached about ½ way up the and run over a sheave at the top stub mast. Sounds complicated, but very simple to rig.

But at some point, I got tired of bolting all the pieces together every time I wanted to sail the boat. So I did what I’ve done with my other three trimarans – converted it into a “folder.” Yep, it adds a bit of weight – as much as 30 lbs. But it makes setup an absolute breeze. You can have the boat 100% ready to sail in well under 10 minutes after arriving at the beach / launch point.

This is the “sloop rig” version, and allows about 150 sq ft of sail to be spread. It consists of a Hobie 14 main (118 sq ft) and a Laser II jib (about 32 sq ft). It is the only “stayed” rig I’ve ever used on this boat. It’s probably the best upwind rig, and possibly the fastest as well.

But setting it all up takes SO much more time and effort than the unstayed rigs require, and it yields a barely noticeable difference in performance. Plus, tending a jib makes for twice as much work, and as with all stayed rigs, the shrouds foul the main sail when you want to go downwind AND the jib would require a whisker pole to catch the wind when running.

All of which brings me to the “final iteration” of how this boat should and will be rigged.

The longitudinal members that ran parallel to the hull, and were mounted to bolts at the aka pivot points, were created for a single purpose: to provide attachment points for the shrouds. Now that I had decided to sail with unstayed masts only, these heavy (and always-in-the-way) pieces could be removed.

That’s what you see in the final shot below. You also see the biggest unstayed rig I’ve ever used – a 128 sq ft full-vertical-batten sail (which I had custom made) on a 23’4” unstayed mast. Although the battens are clearly not full height in this photo, I have since made them that way. And I can tell you for sure that this sail moves the boat at least as well as the stayed rig, and with a whole lot less setup time and tending.

In my view, unstayed rigs are so much handier that stayed ones that I doubt I’ll ever have another of the latter. Yes, big unstayed masts with big sails wrapped around them can be heavy to plug in to their “sockets.” (This one weighs 32 lbs.) So I also had to design a pivoting tabernacle that lets me “front load” the mast at the beach, and then just tilt it vertical. Ultimately, this makes the boat even quicker to set up, especially on very windy days.

So there you have it: One boat that seats two, has three hulls, and has had four different sail rigs. In the end, the blue and white sail won out. It’s easy enough to reef if the wind picks up, but also a great performer in light air. Rigging is quick and easy, and sailing is an absolute blast!

Bottom line: If I never built another boat (which is highly unlikely :), I could be very happy with this one. And if you’ve never experienced the joys of trimaran sailing, all I can tell you is…beware – it can be habit forming!


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