Monday, August 18, 2008

Constructing Cedar Gunwales

The gunwales are the most intimidating thing for me. Back when making the model canoe, I ended up butchering the carving of the cedar stock with a crooked knife and ended up with horrible inwales. It was the spare set of shearing sticks that I used as a substitute that saved the model project. With this build however, I couldn't afford any mistakes.

Eastern White Cedar (Thuja occidentalis) is the wood of choice for making gunwales, but I have been completely out of luck finding an appropriate length & width tree that is also branch-free and straight grained for at least 13 feet. All my resources spent searching and contacting local forestry folks have turned up a dead end. In fact, a conservation officer at my local Minstry of Natural Resources mentioned that in Muskoka, straight knotfree cedar is next to impossible to find. Apparently, most trees around here grow near the shore of the many lakes & rivers here and have a decided lean and spiraling grain.

The gunwale plans; Typical Muskoka cedar

So for this part, I was forced to go non-traditional route and use store-bought Western Red Cedar (Thuja plicata). This species is available in sufficient lengths but like most construction quality cedar, it is quite notty. After spending hours sifting through a pile of 2x6x12s at various home building places, I found 2 pieces that had a completely straight & knotfree grain on their one side. My intention was to split the boards and use the knotfree section for the gunwales. The other notty pieces will be re-used as temporary ribs, battens, etc.

Most commercial canoe builders simply saw out appropriate gunwale stock (usually out of ash or cherry), but because cedar is so soft, I read that sawing makes it weaker by ignoring the strength of the grain. As such, the gunwales are much stronger if they are split and carved out rather than sawn. So the process began by starting the split with my axe and a carved maul from a piece of green hardwood (never took pics of the process). The split was then continued by hand using a forked birch tree for leverage.

Western Red Cedar board; Beginning the split

Leveraging the split with a forked tree

After splitting the other board and the resulting pieces a few more times, I was left with 3 appropriate stock for the inwales (one backup), two outwale pieces, and two pieces for gunwale caps. Given that the inwales are a very important structural component for the integrity of the canoe, the two best pieces were reserved for these parts. After sorting out, the pieces were shaped down with the axe to within 1/4" of the actual measurement. I did this at the communal firepit to add some kindling for the evening campfire.

Shaping the inwales with the axe

After this it was back to the garage for shaving the inwales down to size. Luckily, since the perfect grain was on the outer edge of both cedar pieces, I ended up with inwales that were square on 2 sides permitting clamping onto the building bed and proper marking out with a combination square. With a block plane, these were shaved down to the dimensions from the building plan (5/8" x 1"). Traditionally this step would be done with a crooked knife, but my skill in carving with this tool is limited, so I stuck with what I knew.

Clamped inwale stock; 5/8" width line marked out

An extremely important step is the beveling of the outside edge of the inwale to make room for the rib ends when they are put into place. To make the bevel evenly, I borrowed a trick from paddle making - mark out two lines on adjacent faces, shade in the space with a pencil and plane down on an even angle until the lines disappear.

Marked out bevel outline; Completed bevel

At the tips, the inwales need to be shaped into an arrow head so they can be lashed with roots. I roughly marked out the wood to be shaved so they would fit. This would be smoothed out later.

Marked out tip outline; Rough shaped tips

At this point, the inwales needed to be soaked overnight in the lake for the actual stretching and assembly part. So they were tied in nylon cord and anchored in the same spot as the bark was previously. After I was done, I went back to garage to sweep up the shavings and dumped the load back at the communal fire pit. The day's mountain of shavings turned into a glorious aromatic fire that night.

Soaking in the lake; End of days shavings and scrap

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