We are building Mon Tiki to US Coast Guard Inspected Passenger Vessel specs, and that meant we had to beef up the scantlings, mostly by increasing the per-side stringer count (strakes that run fore and aft on the inside of the hull) from 5 per side to 7 per side, and increase the demension of each stringer from 3/4″ x 1 1/2″ to 1 1/2″ x 2″, or about five times as much lumber as called for in the stringers in the original design.
On Friday we took delivery on over 400 board feet of vertical grain douglas fir, in the form of 2200 running feet of 3/4″ x 2″ staves. Vertical grain doug fir isn’t cheap either; it’s about 10 times what you’d pay for doug fir sticks at Home Depot. But vertical grain means it’s free from knots and other defects, and it has to be: our engineering calculations are based on defect-free lumber.
The lumber came in random lengths from about 8′ to 16′; the stringers are the length of the boat. A not unreasonable question is “How do you make short sticks into long sticks?” The answer is a scarf joint. There are a lot of different sort of scarf joints, but we’re using a simply 10:1 scarf.
We build a jig, and then every one of the 200 or so sticks got cut in preparation for being scarfed.
Then we stacked them all on pipe-racks on the side of the shop.
When the time comes, these sticks will be glued cut to cut, and the resulting joint will be as strong as the adjoining wood.
On Monday our fiberglass, epoxy, and related ingredients arrived. That’s the resin in the black steel 55 gallon barrels. There’s another ~25 gallons of hardener in plastic jugs, about a mile of 6 oz. volan glass, and several different fillers that we’ll mix into the resin to achieve different properties in different uses.
We also started lofting the boat on Monday. Lofting is the process by which the plans are drawn out a life-size so that various part of the boat can be cut to shape.
We stretched a wire tight enough that it sang to use as our baseline, and then started marking of points on the X and Y axis.
For straight lines it’s as simple as drawing a line between each point. Curves are formed nailing brads into a series of points, bending a batten around the brads, and then scribing the line.
Today we were able to draw and cut out the full-size patterns for the keel members and several of the lower bulkheads.
Tomorrow we’ll loft and cut more patterns. On Thursday the BS 1088 meranti plywood arrives and we’ll start scribing the patterns onto the wood that actually becomes the boat!