Building A Small Pack Canoe: Part 7 - Trim Work

Finally, we had a hull. All we had to do was turn that hull into a boat. There was still a lot of woodworking to do at this point, most of it more exacting than anything we had already done.

We had to fashion and secure two sets of gunwales (pronounced "gunnels"). Gunwales are the rails that run along the opening of the canoe. Each set is composed of an inwale and an outwale (curiously, pronounced "in-whale" and "out-whale") that work together to strengthen and stiffen the fragile and flexible top edge of the canoe (called the "sheer").

Since we had purchased plenty of extra basswood, we only used the lightest color boards for the stripping of the hull. We had one darker board that was knot and check free for its entire 12' length. When we ran that board through the surface planer, we received a very pleasant surprise. The entire board had a faint but very beautiful curl to it, almost like a fiddle back. We cut four strips out of it and planed them to 1/2" x 3/4" x 12' long. We knew right away that they would provide a stunning accoutrement to our little boat.

Here's a shot of the gunwales being planed to a taper at both ends. By tapering the ends, we would lighten up the looks of the boat (as well as dropping about 3/4 of a pound), adding a touch of elegance without weakening it in the slightest.










We found a bunch of very robust spring clamps (green grips) for $1 each at Home Depot. As they say, you can never have too many clamps.

The plans called for the gunwales to be glued with epoxy about 1/8" down from the top, and then to trim off the excess planking once the glue had cured. Previous experience (and lots of reading) told me to allow the natural curve of the bent wood define the line of the sheer, but Lady BK and I got into a bit of a disagreement about this. As usual in these cases, the little lady came out victorious. I allowed her to set the gunwales exactly 1/8" below the top along their entire length. The result was that they followed every irregularity along the sheer. This was not in the least apparent since all the spring clamps obscured the line until they were removed after the glue had cured.

If you ask a hundred boat builders what's the most important line to get right, every last one of them will say it's the sheer line. We had just completely blown the most important line in the canoe! A lot of work with sharp block and shoulder planes, together with some very careful observation while re-cutting the tapers in situ, would eventually resolve 95% of the irregularity. At this point, however, I was sure we'd have to cut the gorgeous gunwales off and replace them with wood that was much more boring.

Next on the list were the outer stems. These were laminated ahead of time and fitted to the end of the boat. They were glued in place with epoxy resin thickened with sawdust. Fitting them to perfection wasn't a big deal for me, but carving them to shape so they were harmonious with the rest of the lines of the canoe was a bit of a challenge. The first stem took almost two hours to figure out and shape. The second one took about a third of that time.













Lady BK is shown sanding the edges of the gunwales with a small concave sanding block. I had used a small block plane to cut a nice, even 45º chamfer on each edge beforehand, so all she had to do was to blend the facets into smooth curves.











Now it was time to make and install the breasthooks. No, breasthooks aren't those little fasteners that hold a bra strap together. They are small, triangular pieces of wood that tie in the inwales and the stems. Their shape and placement adds significantly to the looks and strength of the ends, so their construction and installation are important.

We had on hand about a dozen fancy black cherry burls that I had salvaged from my firewood pile. We chose one and cut a couple of slabs out of it about 1/2" thick.




The rough breasthook slab is worked in my small patternmaker's vice to put a slight crown into it, both to shed water better and to add a certain sexiness to it that only curves can do.











A breasthook is trial fitted before gluing. Even though we would use thickened epoxy to glue it in with, I made sure that the sides fit perfectly with the rails. Little details like this only take about five extra minutes and will be there forever to remind you and everyone else how refined your sensibilities are.









Spring clamps and a few clamping pads were all we needed to get the top perfectly aligned while we clamped the breasthooks in place with a small bar clamp.












A bleary-eyed Lady BK laminates yet another strip of bias-cut glass cloth over the gunwales. This will ensure that the relatively soft basswood won't wear through anytime soon. Even if it does eventually wear, a new strip of glass could always be added to the worn area at a future date.










A detail shot of the breasthook and rails under three layers of resin.













Two support thwarts were fashioned to fit at the quarter positions. Here I am using one of my favorite power tools, the oscillating spindle sander. It goes up and down as well as spinning around, leaving a very even finish with no grooves or burn spots. With an 80 grit drum, it's fast as hell, too.














We cut chamfers on the edges of the thwarts to lighten them, but mostly to make them more elegant looking.














Here they are with two coats of epoxy on them. All that's left now is to apply five coats of varnish to everything and fit the seat and backrest. Then off to the water with her for her maiden voyage.

Building A Pack Canoe - Part 6: Fairing And Fiberglassing The Interior

Now that the canoe was off the form, it was time to work on the interior. To do that, we needed a set of holding cradles...

Remember back when I told the story of my eye injury? Well, it was cutting the wood for the cradles that did me in. I eventually finished them, but I know exactly which piece (one of the bottom cross members) originally held the errant wood chuck before it came flying at me, so every time I look at it I get a grim reminder to be more careful.

Anyway, working on the interior is just about twice as hard as the exterior. Not only is the canoe no longer firmly attached to the form, you have to work inside a confined space that is all concave in cross section. That meant that the same tools we used on the outside would be of limited use or downright useless on the inside. A block plane was out of the question, there were only small sections that provided access for my 6" RO sander and long sanding blocks were only helpful for sanding along the length of the canoe. I have some tools that would be considered kind of exotic to the average canoe builder, but (sorry) you go to war with the army you have. I happen to have a pretty nice army.

First off, though, I had to make a tool that would waste away most of the wood. After looking at many books and websites, I found most everybody's solution for interior scraping to be less than desirable.

This is the tool I came up with to scrap away the glue (there will always be much more glue on the inside since you can't easily wipe off the excess while the boat is still on the form) and do the bulk of the stock removal. I wanted something that was both robust and could be pulled along with two hands without digging in too much. I rounded the edge of an old plane iron and screwed it at an angle to the end of a long hardwood handle.


Here it is in use. The end of the handle rests on the surface and the tool is dragged backwards. It made quick work of wasting away about 90% of what had to be removed.











Having a musical instrument building background, I tend to take that kind of approach for much of my other woodworking. A small canoe like this is not much smaller than an upright bass fiddle, so it was inevitable that I would use similar tools and methods as would be used in the construction of a bass.

This is a small scrub plane that I made several years ago for hollowing out archtop jazz guitar tops and backs. It is made from a piece of mountain mahogany (very hard and dense wood), a 1/4" thick slab of silicon bronze and an old file that I heat treated and ground for a blade. The bottom has a gentle arch that just happened to match the curve of the inside of the canoe nicely. It is a roughing tool and it really hogs away a lot of wood in a hurry.

This is a commercially available (through instrument making suppliers) convex bottomed plane that has both smooth and toothing blades and an adjustable throat. It is prohibitively expensive, but I already owned it so I used it. The toothing blade has grooves milled into the back face. This allows you to take cuts in any direction without tearing up the wood fibers








This close up shows what the tool marks look like when the toothing blade is used. It cuts shallow grooves in the wood that are easily sanded out. By crisscrossing back and forth, a very fair surface in easily obtainable. Its ability to cut just as well across the wood fibers as it does lengthwise makes this plane a winner for this operation.










Here's a shot of Lady BK deep in the moment while working on the end of her canoe. I'm sure she was thinking, "If I knew this $**{!#@ canoe was going to be this much work..." Still, she slogged away admirable.
















This photo shows how much wood we scraped and planed away before the final sanding. I weighed all of those shavings for future reference. They only weighed 11 ounces. A quick computation told me that we had removed about 8% of the remaining wood during the interior fairing process, so I guess my original estimate was pretty much spot on. This kind of info will be useful for future ultra lightweight projects.

Now we were down to 11 pounds for the bare hull before glassing the inside. After the final sanding and vacuuming, the inside was ready for us to apply the glass.










Because of the vee-shaped hull bottom and tumblehome/side junctions, we decided to add an extra layer of fiberglass to protect these areas. We cut 2" wide strips along the bias (45º angle) of the cloth weave. We used shorter scrap pieces and overlapped the ends by about half an inch for continuity's sake. This saved us from having to waste large amounts of good glass. I would have preferred uni-directional glass cloth for this application, but I knew the bias cut would be plenty strong enough.

We epoxied these strips into place as you can see here and let them cure overnight. We then sanded the edges to a feathered edge so that the glass laminated over them wouldn't get cut through when we sanded it out.

Next was a football shaped piece of glass to further reinforce the inside of the boat. Conventional wisdom dictates that smaller pieces be placed over larger pieces to avoid sanding through the larger piece during the finish sanding of the laminate, but we knew we weren't going to get anywhere near as fussy with the inside as we were with the outside. No matter how much you care for a canoe, the inside is always going to get abused. You can avoid bottoming out on landings and hitting rocks, etc., but you will always be on the inside, wearing away at the surface. Given that fact, and the fact that we weren't going to use a gloss varnish for the inside (so little things like seams weren't going to show), we decided to go for the easiest way to apply two layers of cloth simultaneously. We knew that the smaller football shaped piece would get dragged around by the heavy squeegeeing we were about to do, so we trapped it underneath the larger piece and made sure we didn't sand too aggressively when it came down to smoothing the interior.

Here's the cloth laid along the inside of the boat and dry brushed into shape.














The ends were slit to allow the cloth to fit around the inner stems and a little vee-shaped "dart" was cut out to allow the end of the cloth to butt up against the stems. Later on, we would put 4" wide pieces of bias-cut cloth over the stems and resin them in place.










At long last, with all of the fairing done and the glass laid in and wet out, we had a hull that would remain stable as we worked on the fit and finish work. We added another light coat of Clear Coat to fill out the weave a bit, but we made no attempt to get the surface as smooth as the outside would need to be. A slightly rough surface on the inside is actually a help in eliminating slipperiness, and since it won't be touching the passing water, it won't create excess frictional drag like it would if we left the outside this way.





After the resin was hard, I used the same 2" slick to cut away the excess glass and then bagged it up to use as clean scraps for the glassing of trim, etc.

We weighed the boat at this point and found it was a fat 14 pounds. With the extra glass on the inside, I figured there was about 15 oz, of glass and 15 oz. of resin, for a total of about two pounds. The extra pound was resin that either was absorbed by the wood (no getting around that) or the little bit of resin that we filled the weave with (one 6 oz. batch).

Building A Pack Canoe - Part 5: Applying The Fiberglass And Epoxy Resin

OK... I messed up by not taking any photos of the outer fairing process. Fairing is the procedure for making the hull of the boat smooth and free from bumps and hollows. No matter how carefully the strips are glued together, there is a little ridge at each strip juncture due to the fact that the strips are flat and they are going around a curved shape. The result is that the surface of the canoe is composed of dozens of facets that all need to be very carefully blended together to get a smooth skin.

We used many tools to perform this operation. First, we used a fine rasp to break off the excess glue that oozed out of each joint. Then we used a small block plane to cut the apex of each ridge and finally we used a combination of cabinet scrapers, power sanders and hand sanding to get the hull surface perfectly smooth and fair. This is just about the most exacting part of strip building, and with a strip thickness of only 1/8" in places, it was imperative that we take our time to avoid sanding right through the hull in spots. This is also the reason why we took so much time getting the strips as level with each other as possible when we were applying and gluing them.

Since the boat is primarily convex on the outside, bumps are what are sought out and hollows are left untouched until the last sanding step. We spent as much time inspecting the surface for bumps as we did scraping and sanding. The job was done when we could see no irregularities anywhere no matter where we placed the work light. At this point we used a paste wood filler to fill all of the holes and gaps, let it dry and then sanded the hull smooth. We then used a shop vacuum with a brush attachment to clean the surface of dust and we were ready for applying the fiberglass.

We cut off 12' of fiberglass cloth (3.2 oz./yard) which left 6" at each end. The cloth was draped carefully over the inverted hull and smoothed out, leaving the excess hanging below the hull.











We used a 4" bristle brush to push the wrinkles out of the cloth. As we brushed, not only did the cloth lay on the boat wrinkle free, it actually clung tightly to the hull surface. In this photo, you can clearly see the wood through the fiberglass cloth.

At this time, I turned on two electric heaters to warm up the room to about 80ºF and let the boat sit in the warm room for several hours to heat up. The idea was to keep any air that got trapped in the wood or under the cloth from expanding and creating bubbles. After we wet out the boat, we turned the heaters off to allow any trapped air to contract, thereby preventing any bubbles from forming. This also allowed the exposed wood to soak up
more resin as the hull cooled overnight.

This is how tightly we got the cloth to lay against the hull by brushing it with a dry brush. This would be critical to the ease we later enjoyed when we wet the cloth out with epoxy resin.

We used System Three Clear Coat epoxy resin with the slow hardener, which gave us plenty of time to work the resin before it began to harden. Clear Coat was recommended by many experienced builders as a wet out coat. It is a high quality, low viscosity laminating resin that readily soaks through the cloth and into the wood below. Since the fiberglass is composed of real glass fibers, the cloth virtually disappears once the resin is poured on.

Here is a shot of Lady BK applying the resin onto the hull. We began by thoroughly mixing up a small batch (6 oz. resin to 3 oz. hardener) and pouring it all at once onto the surface at the center, then spreading it downward and out toward the ends with a 4" chip brush. The less resin you use, the closer the cloth will adhere to the hull, making it both stronger and lighter. However, since the resin will soak readily into the wood - particularly porous woods like basswood - care must be taken to make sure that there are no chalky looking areas that indicate the the cloth is starved of resin.

We kept applying more batches of resin and spreading it out until the entire surface looked uniformly shiny. Then, using specialized soft rubber squeegees, the excess resin was scraped from the surface until the entire boat had lost its shiny look and had a dull sheen to it. Shiny areas mean there is excess resin which must be removed. Excess resin means the cloth is partially floating within the resin and not stuck firmly to the hull. Care must be taken to get every bit of resin removed from the surface before it hardens, but you also have to continue to watch for chalky looking areas that indicate that there is too little resin for good adhesion.

The resin/hardener combo we used hardens in 9 hours, but we gave it 24 hours to get hard enough to sand. We sanded the hull enough to knock off the gloss and then applied a second coat, this time with the regular (more viscous) System Three resin. A third coat was applied in the same manner, but more heavily that the second coat. This coat - known as a "hot" coat - was allowed to flow in a continuous sheet and onto newspaper that had been placed beneath on the floor.






After another 24 hours we began to level the epoxy coat with a sharp cabinet scraper. I can think of no more effective way to remove partially cured epoxy than with a cabinet scraper. It is simply a square piece of spring steel (an old hand saw blade is perfect) that is honed to a 90º edge and then a small hook is burnished on the edge with a smooth screwdriver shaft. When bent between the hands and held at the correct angle, it removes wood or resin just like a plane does - in thin shavings. The beauty of it is that it can be used when the resin is too soft to sand. Partially cured resin gums up the sandpaper quickly. For the sanding that was done in between resin coats, I used two entire sheets just roughing it up for the next coat. On a safety note, partially cured epoxy releases fumes into the air when heated through sanding, so you need to wait until it is fully cured before you power sand it.

This is a close up of a hand scraped area. Note the ridges left in the surface. It is almost impossible to get epoxy to flow out without irregularities in the surface since it is so thick. All I was trying to do at this point was to remove as much of the high spots as possible while the resin was still somewhat workable. There would be more epoxy and glass work on the outside later, so for now I just wanted to get it relatively smooth and then finish up the final sanding after a full cure had been achieved a few weeks later.





Here I am using a RO sander (slow speed) to do a quick blending of the surface left rough by the scraper. I should have been wearing a respirator, but as you know by now, I can sometimes be a bit lax when it comes to safety procedures. Even though the System Three products I was using are considered very low in toxicity, I strongly recommend a chemical respirator if you are sanding uncured epoxy.







Finally, the hull is off the form. I cut off the excess resin-soaked cloth with a 2" slick. It peeled off like butter under the mass of the heavy tool. The individual section molds were then detached from the strong back and knocked toward the center of the boat to free them from the hull. I decided to see how the weight was doing, so I improvised this setup to check it out. Subtracting the weight of the support stick and string, the hull weighed 11 pounds, 11 ounces.

Earlier calculations had led me to believe the hull might weigh as little as 10-10 1/2 pounds at this point. I had mixed up 36 oz. of resin in total and squeegeed off a weighed 7 oz. With a surface area of about 29 square feet, there should have been between 9.5 and 12 pounds of wood in the stripped hull (depending on the actual density of the wood) minus what was faired off (maybe 5-8%, or about 8-12 oz.). 29 sq.ft of 3.2 oz. cloth should have weighed about 10 oz. A 50/50 ratio of cloth to resin by weight is considered good laminating technique, so there should have only been about 10 oz. of resin in the glass at this point plus whatever soaked into the wood. I ended up using an extra 19 oz. due to the absorption of the resin by the very porous basswood. This was unacceptable when trying to build an ultralight boat, but I had to live with the fact that the boat would weigh a full pound more than I had hoped... and I still had to glass the inside. Future boats will be made from much lighter and less absorbent northern white cedar.