Boatbuilding

Scarf or Scarph – The joining of two timbers by beveling the edges so the same thickness is maintained throughout the length of the joint.

All of the plywood has been reduced to strips and chunks of sizes appropriate for fabricating the various parts.

Using 8 foot long lumber to make a 13 foot long boat needs some method of lengthening lumber. Scarphing is the answer. It has been a while since I beveled lumber for scarph joints, so I did a trial run with a few small plywood offcuts. The recommended bevel ratio is 8:1. For the 6mm (1/4 inch) plywood this works out to 1 and 1/2 inch of length. So, I stacked 4 boards with 1 and 1/2 inch offsets and used a few brads to immobilize them. (Hey you guys with the maple / mahogany / purpleheart bench tops that look like boardroom furniture, see why a lumberyard bench is really versatile? Neither my bench nor I cry when I drive nails into it.)

By using 4 boards, the correct planing angle is automatic. The stepped stack sets the right angle and one has to work hard to make it wrong. I started with a block plane, but quickly switched to the jack plane. The jack’s longer nose makes the work more accurate. Extra sharpness is really helpful for this work. Planing at an angle is also helpful. The multiple grain directions of the ply layers are handled much easier with an angled approach. Keep going until there’s a smooth ramp. The plies themselves act as indicators of even planing. They get all wavy when the work is uneven. Keen observers will see some tear out on the fine edge. That’s not a problem, as we’ll see during glue up.

The test of a good job comes from joining the bevels and seeing if the plies of both pieces line up well. Here we see a couple of pieces dry fitted. Looking great. So, let’s move on and plane all the pieces needing scarphing. The bottom is 6mm (1/4 inch) and needs one scarph. There are four 4mm (5/32 inch) hull planks needing scarphs. There are five in all.

Preparing all the bevels wasn’t much work. Actually, it was a lot less work than getting to a similar point with the previous boat where I invested a lot of time in resawing the lumber.

Next comes “glue up.” This is the time when woodworkers usually feel the pressure of glue that’s starting to cure faster than they can get parts aligned. I still have some West System epoxy left from the previous build and am using their slow version. Still, pot life is rather short, and it is good to get all parts stacked up in the right sequence for use, and to have all auxiliary stuff (plastic sheets, clamps, cauls, etc.) close at hand. Rehersal sometimes helps. Yep, I rehearsed this one since I intended to do all joints in one sesson.

I used two batches of epoxy. The first was the standard mix. I brushed this onto all faying surfaces but did not join them. This was to feed those hungry surfaces, essentially priming them so they wouldn’t dry out without providing adhesion. The second batch included enough wood flour to thicken the epoxy to the consistency of mustard. This makes a robust mixture that won’t easily run out of the joint while it cures. It also helps fill in at the very fine edge where there is some tear out. I applied this liberally to one surface for each join and then joined pieces together. A plastic trash bag protects the bench from having planks glued to it. Two hull planks, side by side, made the first pair of joins. Add another trash bag. Do the next two planks side by side. Add another trash bag and do the join for the wide bottom board. Lastly add another trash bag, stack a caul on top and apply some clamp pressure. Epoxy doesn’t need a lot of clamping pressure. Doing so squeezes too much out an leaves a weak joint.

The little bit of glue left after these joins was just enough to glue up two pairs of “hanging knee” parts. We’ll see pictures of them later.

So now, we sit back and watch glue cure … every bit as exciting as watching paint dry.

In which I talk about starting a new boat, and cutting plywood without beer.

Following the successful build and launch of “Eva Won,” I’m now getting started on “Eva Too.” This one is another decked canoe. It will be 13 feet long and built mostly of marine grade plywood using the “stitch and glue” technique. The design is the Mill Creek 13 from Chesapeake Light Craft. This will be Eva’s boat, and she really liked the Mill Creek’s stability rating, its good looks, and its stability rating, and most of all its stability rating.

CLC sells complete kits with all the parts completely cut out, but we’re not the “paint by numbers” type. I’ll be building from their plans but doing all the component prep and construction work myself. The plans consist of six sheets and a hefty spiral bound instruction book. Everything looks straightforward and there are literally hundreds of Mill Creek 13s already built. So, I’m confident this will be a good build. Just saying that insures we’ll probably hear stories along the way.

Stitch and glue boats are built from marine grade plywood. The boat building folks up in Maine advise that anything labeled “marine” means only that it costs three times more than normal. This plywood meets that description. Yet, there really is more to it. There is a fairly rigorous standard which requires knot free face veneers, absolutely no core voids, minimal ply thicknesses and counts, waterproof glues (duh), and other size tolerances.

My plywood is Bruynzeel Occume which uses gaboon as the face veneer. While not a true mahogany, gaboon has a similar appearance, is cheaper, and is far more plentiful than mahogany.  M. L. Condon in White Plains NY is the lumber yard I frequent. I’ve seen people complain that Condon’s prices are high, and they are. However, once one factors in transportation the price differences disappear. Buying from a distant supplier entails transportation charges of $150-200, and I can drive to White Plains for less than $15. Add to that the ability to walk the yard and hand pick material and Condon works out very well. While I was handing sheets down from an upper level bin to a yard worker below, I mentioned that the top sheet in that stack was a “bit ratty.” It had some edge damage that extended 4-5 inches into the sheet. He said, “Hey. I’d like to get that sheet out of here, how about I knock of $14?” Being familiar with the cut plans, I knew I could work around that damage and gladly accepted a 20% savings. This meager pile of lumber is almost all I’ll need. It is three sheets of 4mm plywood, one sheet of 6mm plywood, and an ash 1 by 6 of which I’ll use a pittance (discounted for that knot). Another stick of spruce or fir from “the Borg” will provide internal framing.

It’s been a very long time since I cut plywood, and the memory makes only part of the experience appealing. Decades ago, I had no saw benches, a couple of sheets of plywood to cut, a circular saw … and a six pack of something cheaper than Budwiser. So, I spread out those six cans strategically, balanced precariously over the wobbly arrangement and went at it with the noisy spinning thing. I survived with all fingers, but resolved, while drinking my bench, to avoid cutting plywood as much as possible. No problem today, no need for a beer can bench. By some unforeseen and unplanned stroke of genius I built both my workbench and the previous boat’s strongback to within 1/4 inch of the same height. They now become two very sturdy sawbenches, upon which a monkey on all fours can use a simple handsaw to make easy work of breaking down the plywood.

We’ve had a comfortable Fall this year. The woolly worms are woollier. Deer fur is darker this year than in others. The Old Farmer’s Almanac predicts a colder winter for the Northeast, and Al Gore is too busy PhotoShopping hurricanes to notice. Starting a project that uses lots of epoxy in an unheated workshop nearly guarantees immediate and precipitous temperature decline. We’ll see…

Be careful what you say. My original plan was a pair of his and her Fiddleheads. That went awry when I said something about “Eva Won” being a bit tippy, at which my dearest immediately rejected having a tippy boat. So, we have been considering other designs, ones that have a tippiness factor like that shown on one of Chesapeake Light Craft’s stability gauges.

To the defense of Harry Bryan, the Fiddlehead designer, if his design were measured by CLC’s factors, it would very likely be only one tick down from “very stable.” The problem is not the boat, but me, a novice boater who thinks all small boats somewhat tippy. As Nick Shade, of Guillemot Kayaks, says, “The same boat that is a threatening death trap for a novice may be stodgy and boring to an experienced extreme paddler.”

So, we have been shopping for another design. At first, I threatened one of those square aluminum fishing prams, but came around quickly to looking for other solo canoes or kayaks.  We now have plans and construction manual for the CLC Mill Creek 13. It is one of CLC’s early designs and thousands have been built. We’ll add one more, Eva Two. She’ll be stable not tippy and red.