TriloBoat FAQ Page

T32 in Profile

What is a TriloBoat?
What do the different TriloBoat names mean?
What sizes do they come in?
What's the difference between a Barge and a Scow?
What's the difference between a Barge and a Sharpie or Dory?
What are the advantages of the Barge shape?
How do TriloBoats differ from barges in general?
What're the DISadvantages of the TriloBoat shape, and will they be able to sail?
Are there any special recommendations for sailing TriloBoats?
So where will TriloBoats 'shine' and where not?
I want to look into this... what are 'StudyPLANs'?
What? Why no real plans?!
What if I want to make a few changes?

Do you recommend a particular construction method?
Are TriloBoats sheathed with fiberglass/resin?
What was all that about plate copper sheathing?
Any last words?
Bonus Section on Puddle Duck (PD) Racer Variations


What is a TriloBoat?

TriloBoats are a family of barge/scow hulls that have been adapted for fast and easy construction in plywood. They are a 'formula' design, which means that a handful of simple rules generate many different models of varying length and beam. They are suitable for sail, power and permanent mooring.

What do the different TriloBoat names mean?

TriloBoat names give the length and beam of a particular hull in feet. For example, a T32x8 is a TriloBoat that is 32 feet long, and 8 feet wide.

What sizes do they come in?

Commercial ply comes 4 feet wide by 8, 10, 12 and 16 feet, becoming disproportionately more rare and expensive as the length increases. The whole-sheet TriloBoat formula calls for one sheet wide, and any number long (but don't get crazy!). If four sheets is a reasonable maximum, that means they range from T8x4 to T64x16. If you allow half-sheets or mixed length combinations, you quickly pass a hundred possibilities.

I would think that the T8, T16, T20(?), T24, T32, T36 and T40 with various beams would be the most popular.

What's the difference between a Barge and a Scow?

It's a question of splitting hairs. Local names lean one way and the other, may involve flat, V or arc bottom portions, power or lack of it, what's being hauled, etc.. YAWN (Oh, look at the tide... gotta go!). I call TriloBoats 'barges', but hey, I'll call it a 'scow' if you want me to.

What's the difference between a Barge and a Sharpie or Dory?

There are a bunch of fuzzy thresholds distinguishing types of boat and rig (made fuzzier, no doubt, by the swilling of spirits), which boat enthusiasts take more or less seriously. While I tend to the less serious side, there are some broad differences between a barge and a dory or sharpie.

My distinctions tend as follows:

A BARGE tends to 'slab-sides' and 'firm bilges' (rectilinear in section), carried well forward and aft. It has a dead-flat run somewhere along its bottom, as seen in profile view.

SHARPIES and DORIES, in contrast, tend to have constant rocker (bottom curvature as seen in profile view) usually considerable flare, and beam tapers away from its maximum point amidships (side curves, seen in plan view).

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What are the advantages of the Barge shape?

The prime advantage is a barge's increased displacement. That means you can carry more stuff.

A barge is very nearly a rectangle, which displaces the maximum amount on a given beam, draft and length. Any shape which carves away from that volume with rocker, flare, rounded bilges or plan view curvature (e.g., curving in to a point or transom), will drop in displacement. To illustrate:

barge vs. sharpie

Barges carry all that extra displacement well outboard with firm bilges and flat runs amidships. This means they are initially stable and not prone to pitching, though their motion, if light, may be quick. They can carry, or stand up to more sail on given dimensions than other boats.

Contrary to what you may have heard, barges have more reserve stability, on a given dimensions, than any other hull form. When you hear otherwise, the comparison is "cooked" by adding flare to the bottom beam and claiming victory (sorry, sharpies and dories always tend narrower than a barge on the same length)—this increases overall beam, of course... if you let the barge catch up, it wins in both initial and reserve buoyancy. The curve of buoyancy is different, however, than in a flared hull. A barge's reserve is small in proportion to its large initial stability, the reverse of the common case. This means that the transition between upright and stable and knock-down, while harder to bring about, isn't going to linger as long in-between, a fact which should be kept in mind if you insist on sailing on your ear.

Here're a few other barge advantages (I'll include summaries of the above):

  • Generally, barges are relatively inexpensive to build. They maximize volume vs. surface area (e.g. material cost).
  • Maximum displacement on a given overall dimensions (length, beam, draft).
  • Adequate displacement on short length saves money in harbors and, in our area, taxes. Both charge by LOA.
  • Maximum form stability for the same givens (this, to me is a critical virtue). Bolger comments that the "box" chines act like a narrow catamaran, with displacement outboard for increased form stability. As a bonus, the very hard chines are roll-damping and track well.
  • Maximizes stowage: Unfortunately, the best area of any boat is along the mid-line, and that's given over to empty space (gangway). Side and bottom curvature cut away from volume along the hull, which means cutting into stowage. Barges hold this to a minimum.
  • Right angle stowage along the chines (vs. roughly triangular spaces in the typical boat). This allows very cheap and easy storage solutions in comparison to most hull shapes (at least in smallish boats where one is always living near the hull. It almost eliminates the need for special solutions for straight gear against a curvy hull.
  • Barges have a dead flat run, which allows sitting upright on a beach, and a flat sole with constant headroom.
  • Barges maximize deck-space, enabling easy and cheap solutions for such things as boat covers, gear stowage, PV foot-print, dinghy stowage. There is more space for clear paths forward and lots of room to work anchor gear, both of which are important safety considerations.

Whew! Aren't you glad you asked?

How do TriloBoats differ from barges in general?

TriloBoats maximize whole and half-sheet construction, and right angles:

  • Whole and half-sheet construction, joined in line or at right angles (only a few exceptions) holds layout, cutting, beveling, joining, truing, spiling and a multiplicity of parts to a bare minimum. These details add up to long projects. Eliminating them makes for radically shorter building times.
  • They are easy to design: graph paper works fine without the learning curve and time required to fair curves between views. You can build from notes without laboring over a "fair copy".
  • They can be built with basic carpentry skills; kids can pitch in at high levels throughout the project.
  • Easy right angle joints (built up from factory milled faces) require less expensive glue (gapless joins) and eliminate weakness in situations where the glue is weaker in the gap (e.g., liquid polyurethane).
  • Allows building with sheet materials (ply, copper, foamboard, etc): sheets plank a boat very quickly and complement water-PROOF, monocoque construction. Barring a breach, your bilges should be reliably dry.
  • Right angle chines can be protected with common angle iron or bronze, which can also cover the joint between side and bottom copper plates. Great for settling down on not-quite-rock free beaches while swinging in wind or current.
  • TriloBoats are easy to move. They have great planes for jacking, and, with their long, flat run, rollers work well under the hull (continuous rocker tends to make uphills of every roller, concentrates load on one, and often bottoms out on the downside, stalling progress and endangering fingers and toes or worse). Their monocoque, girder construction makes them very robust (you can jack anywhere in the vicinity of an edge or bulkhead and no torquing worries). Traditional boats must be handled carefully, and often require moving cradles.

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What're the DISadvantages of the TriloBoat shape, and will they be able to sail?

I'm betting that they will be decent (not stellar) sailors.

The following are TriloBoat cons:

  • They have high windage, relative to their "grip" on the water.
  • Their upwardly curved, flat bottom at the bow won't be cleaving a chop (interestingly, though, the super blunt bow of Dutch boats is often explained as providing extra buoyancy to lift them up and over the nasty chop of the North Sea—Andy has had his T32x12 in 5 ft chop on the edge of the Gulf of Alaska. He reports no undue pounding and good progress under light power (8hp outboard)).
  • Their heeled waterline is going to be one weird, fat banana (technical terms that bode not well).


  • A shoal hull, so long as you don't plow water with a transom, doesn't have far to shoulder water aside, allowing even a broad bow to ease through the water.
  • When heeled, their hard chine becomes a V, which slips along and tracks well.
  • Their high stability allows them to carry more sail.
  • Off the wind, they are a toboggan, or skimming dish, or belly-whopper (take your pick).

My conclusion (re enforced by our experience on LUNA, which is what you get when you cross a barge with a sharpie) is that they will make reliable sailors. By that I mean that they can work steadily to windward (albeit slowly) in heavy weather. Off the wind, they'll fly.

Here's a pic of the ALMA (taken by Charlie Bergstedt), close-hauled and sailing to windward in what looks to be about 15 knots of wind, and her lines, which are reasonably close to a wide TriloBoat's:


ALMA's not heeling discernibly, despite flying all her working sail (main tops'l not set). She's dragging no large wake, and by her angle to waves and flags, appears to be 50° or less off the wind (not bad for a sailing palace!). All these point to decent sailing qualities.

Alma's lines

TriloBoats have an easier entry than she does (ALMA is built "backward" relative to modern thinking—blunt in the bow, easier at the stern). She carries a "broad bone in her teeth" (the white splash across the bow). Any pitching tends to throw water forward, absorbing energy that would be better used for speed. This is endemic to boats whose bottoms curve up and out of the water (sharpies, barges, scows, garveys, skipjacks and dories... not all do, but it's more rule than exception). Nevertheless, many of these are known as fast types.

I'm hoping that we'll have a large, sailing TriloBoat soon, to start generating some first-hand experience. Stay tuned.

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Are there any special recommendations for sailing TriloBoats?

Yes. I'd recommend keeping the ends high (to clear the water when heeled), raise the sheer along the cockpit (optional, but I like a little distance) and keep the LOD to Beam ratio at or narrower than 4:1. Narrow for length, all things being equal, always improves a hulls speed.

Consider an aft bottom curve, rather than the "knuckle", in order to "release" the water more smoothly. Just fair the transition, starting at the aft bulkhead, and construct as at the bow.

Consider a larger sailplan (possibly junk rig for easy handling) to offset sailing qualities lost to curvier hulls. The barge can stand up to considerably more, so make use of the extra drive.

So where will TriloBoats "shine" and where not?

Picture a spectrum with a quiet anchorage at one end and a confused sea lashed by hurricane force winds at the other. Now picture where you see yourself sailing most often. Same process as choosing any boat.

TriloBoats will make the most of a harbor, and cruise comfortably a good way up that scale. Ocean passages are quite possible, given adequate construction and preparation, and I believe that they will be keep the sea even in extreme conditions. But I myself wouldn't choose one as a chronic blue-water cruiser (occasional passages, maybe, but not to live at sea) or even as a frequent passage-maker in persistently sloppy conditions, if I could afford curvier alternatives.

Anke and I cruise Southeast Alaska, which can get truly wild, without an engine, often sailing in gale force winds. Yet we feel that a TriloBoat will be perfect for us (we plan to build a T36x8). We have the leisure to wait out bad conditions, however, and the channels of the archipelagos are deep (longer wave patterns than, say, in the Chesapeake), we don't have nearly the wake problem common to more congested cruising grounds, and hidey-holes abound for the shoal of draft.

Not much advice, but I hope that helps.

I want to look into this... what are 'StudyPLANs'?

StudyPLANs are actual plans (unlike a study plan which is pure eye-candy). They contain all the "dots" necessary to build a particular set of TriloBoat hulls (interiors, rigs and deck arrangements are left to the builder). Each is for a given TriloBoat length, and covers the various whole-sheet beam options for that length.

They are not like ordinary plans in that methods and materials are suggested, rather than specified. These are wide open designs, and require your active participation. Unlike the T16x4 Plans Package, these studyPLANs are for those who feel confident in their ability to research and draw their own conclusions regarding methods and materials. For others, they may be enjoyed as an ordinary study plan, with the understanding that more specific plans will not be forthcoming.

What? Why no real plans?!

These boats are too inexpensive to support the kind of plan prices that justify individual design time (and besides, there are a gazillion possible variations). With a little guidance, you will be able to do it yourself in less time than it would take to describe your wish list to me. AND you'll know your boat and plans inside and out.

To that end, I'm working on a DIY Design and Build Your Own TriloBoat Book, chock-a-block with everything I know on the subject. It will allow you to design your own TriloBoat at any size and cover strategies, materials, construction methods, variations, interiors and basic rigging options. It will supercede the StudyPLANs.

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What if I want to make a few changes?

Go ahead, it's your boat. Keep in mind that you'll want to weigh the costs of your changes against the benefits. TriloBoats are trimmed close to the bone. Variations are limitless, but each change costs a little bit, alone, and often ramifies through the hull.

For example, say you want to pull the sides in a bit at the bow (a la ALMA); a simple, little tweak. You'll need to layout and cut the foredeck, bottom and transom, which now needs side bevels. A log chine will have to take the bend, or give it up for tape-n-glue. Any panel work you've been doing on the bench before assembly will have to either remain flexible or be pre-bent to shape before assembly. The bunk (which is probably in the bow section) has to be spiled, laid out and cut to fit. Its cleats must take the bends. Any bulkhead repeats bow transom extras. If you're using angle iron over the chines, it must be curved in two dimensions.

Of course, if you want balanced ends, you'll probably want to bring in the stern, as well... get the picture?

Do you recommend a particular construction method?

I personally like chine log construction, glued and nailed, which is quick, inexpensive, strong, uses widely available materials and not as messy or toxic as tape-n-glue methods. I tend to mix and match, though, to meet particular challenges. In some variations, say, I might tape-n-glue a compound bow curve (see above) rather than try to bend lumber.

Are TriloBoats sheathed with fiberglass/resin?

Again, it's your boat. Anke and I don't sheath our boats, generally, and nothing bad has happened. Plenty of ply skiffs up here look good after 20 years, even when maintenance has been spotty. We're leaning toward Dynel cloth for our next decks, though, but may settle for taping butt seams. TriloBoats are easy to sheath if you want to.Your call.

What was all that about plate copper sheathing?

Plate copper provides great mechanical protection for grounding, and non-toxic anti-fouling. It is initially expensive (at this writing, it's running about $5.25/lb), but pays for itself quickly in haul-out avoidance (haul-out, yard fees, paint, brushes and such, treats = $$). It dissipates a lightning strike when bonded to your protection system. It's high on the galvanic scale, so you need fear no "hot" neighbor. If your motor lifts out, you are mono-galvanic (copper and bronze) below the waterline, so no zincs. It's heavy, so you'll make up some of the cost on ballast savings. Nail, screw or glue it on (be sure to test your glue on copper, first) and cover the chines with bronze angle.

Another, cheaper option (way second best, but don't stay ashore waiting for copper prices to drop!) is to add elemental copper powder to epoxy, and coat the hull below the waterline. A light sanding exposes copper, which lasts a good long while. When spent, sand again. Mix it yourself to save $$ over commercial products.

Of course, you can use any compatible anti-fouling system.

Any last words?


Think about why we want a boat at all. Most of us want to get to Magic Harbor safe, sound and stylin'. We want to drop our hook, and settle in to enjoy some peace and quiet with our amenities close at hand. Maybe do a little fishin'. A nice view? Yes, please!

We don't plan to sail around the world against the trades, win the America's Cup, or keep up with Jones, over there, who just plunked a quarter mil on a boat he'll use precisely once. We don't want to waste our precious lives on spit and polish.

We want a boat that we've built with our own two hands without having to sell one of the kids or take a freaking decade or suffer a divorce.

Whatever design you settle on, have fun with the process. But DO get out there... we're none of us gettin' any younger.

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Bonus Section on Puddle Duck (PD) Racer Variations

What are PD Racers?

Puddle Duck Racers are the brain-child of Shorty Routh. They are rectilinear in plan view and the bottom curve of their sides is defined in profile. That's about it. Visit for full details.

I, who have not the least twinge of racing mentality, am very excited about PD Racers. They're fun, accessible, create community and draw people to the water.

What have they got to do with TriloBoats?

The PD bottom profile is compatible with TriloBoat upper hull and plan view specifications.

New classes of PD Racers are open for definition by whomever completes hull #1. All that is required is that they be scale variations of the original PD Racer proportions (length, breadth and height may each be scaled independently). Visit for the rules for declaring a new class of PD Racer.

This means that you could slap a scaled bottom profile onto any TriloBoat size and define a new PD racing class. Or, if someone has already defined the class, you can build to their specs and race them, head to head.

What are the pros and cons of altering a TriloBoat this way?

Pros are that they have a shot at being somewhat faster than a standard TriloBoat (the bow curve is extended to amidships and the aft curve nearly so... the dead-flat is confined to 1/8 of the overall length), and that you can race them with others in your class.

Cons come with increased building time and material waste. Transverse planking will still be mostly whole-sheet, same as a TriloBoat. But the longer curves mean that the rectangular, box mid-section is compromised. Straight chines can't be used, and much more spiling, layout and cutting of sides and interior furnishings will be necessary, creating waste in the process. PD variations are still relatively simple boats to build, but there will be a substantial difference.

Also, your displacement will drop, relative to a standard TriloBoat (you're cutting away hull with longer, shallower curves).

A (probably) neutral difference is that PD Racers are nearly full rocker. They may pitch a bit more and be harder to move on rollers, but their bottoms will be somewhat stronger and you might be able to back them off a grounding easier (depress the stern, raise the bow).

Lastly, the variation will only truly pay off if others build to your new rules. Unless they do, you're just a "lone duck".

Is there anything special to consider in choosing my scales?

Yes. There is likely to be a distinct difference between boats designed as light, open racers versus heavier cabin cruisers. The latter will need to have a scale chosen that keeps the transoms well clear of the water when heeled. Be careful that cruising qualities aren't marred by the variation.

Tell ya what I'm gonna do...

If you would like assistance in developing a PD/TriloBoat class, contact me. I'll work with you, draw up your lines and, once you've completed your hull, post them, free of charge for other PDT builders in your new class.

If you prefer to work on your own, please let me know once you've built, and I'll post your class lines with the relevant hull size and/or link to your site.

Just remember that only those who complete a hull may declare a new class of PD Racer.

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