Ama Construction Begins
09 February 2017 | St. Marys, GA
Capn Andy/mild winter
It was time to start cutting out the hull sides of the ama for the outrigger canoe. I used the old offsets from the ama built in 2014, but had raised the lee gunwale of the ama a bit so that the deck of the ama would match the curvature of the crossbeams. The plywood was cheap 1/8" doorskin from Home Depot and I used the multitool with halfmoon blade to cut the parts out. There were 4 halves of hull sides and will join amidships. I will use the same technique I used on the tortured ply canoe of 2014. The hull sides are not scarfed together or joined at all, just butted together and the gunwale stringer is glued onto them. That joins them together in a way, but the gunwale stringer is only 3/4" square, so it can snap if not handled with care.
The two hull sides are laid on top of one another, keel to keel, and gunwale to gunwale. The keel edge is drilled on 3" centers about 1/4" from the edge. Both keels are drilled together so the holes line up exactly. Copper wire is then passed through each pair of holes and twisted to tie them together, but left a bit loose. Only the keel edge is wired, only up to the knuckle of the bow(s). Next the bulkheads are jammed down into the hull while pulling the gunwales up tight to them. This is accomplished by drilling small holes through the hull ply just under the gunwale stringer and straddling where the bulkhead edge will lie. Strong twine is threaded through the holes and over the gunwale, over the top of the bulkhead, and through the other holes in the other gunwale. The twine is then tightened with a spanish windlass which brings the gunwales toward each other and pushes down on the bulkhead, forcing it into position. The bulkhead can be tapped this way and that to position it exactly, then the inside of the hull sides can be marked as to where the bulkhead will be positioned. Because the bulkhead can distort the hull side, a butt strap is laid between the edge of the bulkhead and the hull side. The bulkhead then is bearing on a double thickness of plywood. The edges of the butt strap are marked on the inside of the hull side and the edge of the bulkhead is marked on the butt strap. When it's glued up these pieces can be placed in exactly the same place where they were dry fitted.
The hull can be wound up into shape with spanish windlasses at each bulkhead, and then wound down again for any modifications for fit or to remove twist from the hull. The single seam in the hull side is at the middle bulkhead and the edges of this seam have to be relieved so that the ply edges fit exactly. The top of the edge, at the gunwale, is already glued to the stringer and is butted together. When the hull is wound up, the bulkhead pushes the seam outwards and the crack opens up. The edge is trimmed back a bit at the keel and a bit less on the way up to the gunwale. By cut and try the seam is made to fit. It takes a few sessions of winding up the hull, marking the seam, then unwinding, trimming, and winding up again, until it fits.
The hull is then glued up, at least the bulkheads, butt straps, and hull sides are glued up. The hull is adjusted while the glue is wet for twist and any unfairness. Clamps, bungies, sticks, and string can be used to force the hull into a fair shape.
After the gluing of the bulkheads, the inside of the keel and the bows can be filleted and taped with glass. The ends of the gunwale stringers have to be beveled where they meet and cut back to a point where the desired radius can be rounded on the point of the bow.
The photo is of part of the glue up of the ama hull sides and gunwale stringers.