Sunday, April 27, 2008

Carving Permanent Thwarts

The gunwale assembly has been held together with temporary thwarts lashed to spread the hull. Time had come to carve permanent thwarts which would eventually take their place. Another piece of broken gunwale batten shaved to 1/4" thick was used as the source.

The centre thwart tends to be functional as well as decorative and I wanted that authentic flare with this model. Similar to the stem piece, I simply traced the half images of the thwarts from the enlarged 1/4 scale "blueprint". These were then transfered to my piece of cedar. The intermediate and end-thwarts for the Attikamek Hunter's Canoe are simple cross pieces with tapering ends that were easily shaped with my knife. The center thwart, on the other hand, needed to be specially shaped and following a tip by Ted Behne, I decided I would use a coping saw to get the rough shape.

Stock for thwarts; Images from blueprint; Marked out centre thwart

In a full size canoe, the thwarts would be made of hardwood - typically ash, maple, or birch and I had some stock left over from paddle making. But I decided on using up the scrap pieces of cedar from the kit rather than using these hardwoods - something I very quickly regretted. I had clamped the cedar lightly into a vise and started cutting out the pattern.

Cutting out with a coping saw

Within moments, the whole thing split along a grain line and ruined the thwart. Instead of carving out another piece of cedar, I salvaged it by simply redrawing the thwart image towards the edge and beginning again. This time with more delicate sawing strokes, the centre thwart survived the process. But when I tried to use the Mora knife to thinly shave and clean up the sawcuts, I ended up splitting off the decorative part of the thwart. Not wanting the experience to be a total waste, I deviated from my "authentic model" by glueing the broken piece with some Gorilla glue.

Split thwart; Resawn with broken end; Glueing repair

Once it was repaired, the ends were tapered with a block plane (gently). The photos below show the finished thwarts from the front and profile view.

2 view of the permanent thwarts

Ultimately these will be fixed to the gunwales with a mortise joint and lashing but it'll be a while before that stage.

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