A quick musing on epoxy use – or overuse – in wooden boat building

The most recent issue of WoodenBoat includes part I of a three-part “how to build” piece on the Phoenix III, a cute sprit-rigged day-sailer from the desk and shop of Aussie Ross Lillistone’s Bayside Wooden Boats. As is generally the case with these pieces in WoodenBoat, the boat is pretty and fun-looking, the article clear and interesting, and the detail on target for the need. Mr. Lillistone clearly has a nice eye as a designer and we are sure he is a great boatbuilder. We don’t want to impugn the big-picture here at all; again, we really like the looks of the boat.

One bit in the article really bugged us, though, and we are interested in others’ opinions. In writing about setting up the transom, Mr. Lillistone writes:

The transom edge, like the bulkheads, is simply cut square, relieving the builder of the tricky process of cutting compound bevels on its edges. The planking will contact only the outer corner of the transom. This is no cause for worry, since the gap will be filled with thickened epoxy when the hull is being planked. After the planking is completed and the hull turned upright, this joint will be further reinforced with a large radius epoxy fillet and double-bias ‘glass tape, making it exceptionally strong.

We would fully expect the method described to do the job, but does it strike anyone else as crossing a line from being accessible to being sloppy and leaning on a crutch? We here at Chine bLog are all about getting as many fine boats like the Phoenix III built as possible and that clearly means knocking down barriers to entry. Epoxy and ‘glass methods like stitch-and-glue, lapstrake-plywood, and the like are valuable ways to do this. We find ourselves getting ruffled, though, when we are leaning on epoxy so much that joinery is getting tossed out wholesale. Yes, the bevels present some extra work, but it’s hardly the trickiest task one faces. We would be curious to hear what you, our readers, think of this. Is there a line of artistry the we should try to hold or have we gotten curmudgeonly here?

5 Comments for “A quick musing on epoxy use – or overuse – in wooden boat building”

Andy Margeson

says:

Assuming the epoxy method is sound, he may have been thinking, “woodworkers who can cut compound angles will know what to do, so I’ll just write about the method than beginners can use.

For those of us who have never built a boat, it sounds pretty daunting, so authors may try hard to simplify it as much as possible.

says:

I got a nice replay a bit back from Richard Scofield at Chesapeake Bay Maritime Museum. I have excerpted his points here.

“I was fascinated by the article you quoted from Wooden Boat about just filling the transom bevel with epoxy… Not beveling the transom and filling the gap with epoxy is… wrong. Shaping a bevel, and especially a rolling bevel, is a wonderful challenge. And if you don’t take the time how would you ever know how it SHOULD be done versus how you are doing it. I really question the strength of doing the transom that way, but let’s assume it does work. What you have done is cut a corner without really understanding the process. It is like drawing on CAD with out ever drafting with a pencil and a T-square. Or using a calculator with knowing your multiplication tables. You cannot build a house with out a foundation, nor can you acquire a skill with out the building blocks that support that skill. Does that make me a curmudgeon? Of course it does, but I think you will find that my apprentices appreciate having some old school them in the old ways because it helps them understand the foundation of this whole foolish boat building thing.”

Ron

says:

I would guess it depends on what you like. Skills with wood. How much time you are willing to take. Money? A gap filled with thickened epoxy and smoothed out will be strong and look good. Keep the wood from rotting. I’s the boat a dayboat? Kept dry, i would use less epoxy.

says:

Dear Tim and respondents,

I have only just come across this site, and I’m interested to have read the comments regarding the stern transom construction specified in the instructions for my ‘Phoenix III’ design.

Like you, I am not fond of using epoxy, but over the years I’ve improved my techniques, becoming more neat and sparing, and I regard epoxy to be a tool – not a magic bullet. The vast majority of the ‘Phoenix III’ plans end up in the hands of unskilled amateurs, and although I encourage extensive reading ( reading list accompanies the instructions), the building of models, and the construction of small and very simple boats as a starting point, most people bite off more than they should first up.

With the above in mind, I wrote a sixty-plus page instruction manual, which is heavily illustrated. The design has five strakes per side so as not to overload a first-timer, and I give detailed instructions about spiling, cutting gains, and cutting the rolling bevels for the plank laps and the keelson (or apron). Builders also have to contend with the rolling bevel on the inner stem – all quite intimidating. I’m a trade-qualified boatbuilder, and I know how to cut compound bevels, and how to bevel the transom edges for a round-billed boat. But for a beginner who hasn’t learnt how to do a full-sized lofting, transom bevelling is tricky.

As you say, learning how to do things the ‘proper way’ before indulging in the use of labour-saving devices is the way to build understanding. I do full-size loftings, and for much of my life I drew lines on a drawing board using splines and ducks. However, I now use a VERY basic 2D CAD program for my drafting – but it is all done individual line by individual line. Would you insist that people calculate areas of irregular shapes from first principles because a planimeter is cheating?

My designs (at least the published ones) are trailer boats, so must be built using techniques which allow the boat to survive dry and be bashed around at highway speeds. These boats must be light, exceptionally strong for their weight, and be able to survive extremes of temperature – not to mention less-than-expert construction.

The open V filled with epoxy, given a specified radius cove, and then reinforced with 450gsm double-bias glass tape provides a superbly strong and durable engineered joint in a highly- stressed part of a trailer boat – one which may well be carrying an outboard motor and a rudder when travelling at speed on a trailer.

I prefer working with wood, sharp edge tools, silicon bronze and copper fastenings, and solid timber. But I am also a realist. By the way, in ‘Phoenix III’ the entire planking-to-transom joint is contained within a buoyancy compartment, which not everybody will ventilate in a disciplined manner. My specified joint (besides being stronger), will outlast a traditional joint in that region many times over.

I was grateful to have the opportunity to write the ‘Woodenboat’ article, but it is a pity that the majority of the photos were from amateurs.

Thanks very much for your interest, and for bringing up the point-of-discussion.

Sincerely,

Ross Lillistone

says:

Ross – thank you so much for replying, and in such a helpful and thoughtful way. Your points are good ones and I am thrilled that you participated in the discussion. Good luck with your great-looking boat.

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