Gunwale to Deckbeam Joinery
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Gunwale to Deckbeam JoineryThere are a number of different ways to joint gunwales to deckbeams. We will demo four of them.
Mortise and TenonTo make this joint, we cut a tenon on the end of the deckbeam and carve a mortise or square hole the size of the tenon in the gunwale. Then we assemble the two. The shoulders of the tenon are cut at an angle to match the angle of the mortise. This is the angle that the deck beam will make with the gunwale.
While this joint takes a fair amount of marking and cutting and careful fitting, the payoff for all this effort is that this joint very firmly aligns the deckbeams and gunwales at the angle that you have cut your mortise and tenon. Assembly simply becomes a matter of sliding the pieces together.
Doweled Butt JointThis joint is simpler to make than mortise and tenon but requires greater care in assembly. The thing to watch out for in this method of construction is that the gunwales are properly aligned before the deck beams are doweled to the gunwlaes. Otherwise any misalignment or twisting of the gunwales becomes permanently fixed in place.
East Greenland JointThis joint is similar to the doweled butt joint except that a notch is cut into the gunwales. The end of the deck beam which is cut to a more acute angle than the notch sits in the notch. The joint is then doweled and lashed. Unlike the butt joint in which the dowels go into the end of the deck beam, in this joint, the dowels go into the top of the deck beam, come out the bottom and go into the gunwales at an angle. This joint is also lashed to keep it from coming apart.
This is the notch cut into the gunwale in which the end of the deck beam will be seated.
Stone Age Joinery
Before steel tools became available to kayak builders, they had to carve all of the frame components with stone tools. Making mortise and tenon joints was out of the question. Drilling deep holes with stone tools was likewise difficult. This made doweled construction difficult.
The solution that builders used was to carve shallow depressions into the gunwales and then set the deckbeams into the shallow depressions and lash them in place with lots of lashings. The lashings ran from gunwale to gunwale to pull them together to keep the deck beam from popping out of place. In addition, the lashings ran around the deck beam to keep it from sliding upwards and out of its seat in the gunwales.
All content copyright © 2005 Wolfgang Brinck. Personal non-commercial use permitted.