I’ve read a few places you can’t steam wood a second time. That is a little simplistic. Since in neither case was there any support for the statement, I think it might have been one source and repeated. You can: all you’re doing is making the lignin liquid so the cellulose will slide, but you do have to watch out the wood hasn’t dried out. Tamboura’s ribs were air cured not kiln fried, and before initially steamed they were tarred and oiled a few times, then again before I steamed them again. So they should be wet enough inside. And I’ll tell you a real reason why a second steam is real tough. At first rib stock is straight and can slide in a simple steam box. Once they’re arced they can’t be stuffed in a straight tube anymore.
So I made a flat square steam box. Tied the rib’s ends so while heating they’d stay the shape they’d been. And cut a female mold for the form of every second rib. Then let each rib cool held rigidly to it’s perfect shape for 48hrs. So by the time the ribs went back into Tamboura, they had deeply settled into the precise shape they’re supposed stay.
I’m finally (more on that later) starting to tie her all together. As mentioned, the Mainwales provide primary attachment to the breastblocks. And the ribs, and the thwarts.
Ribs are being lashed on.
I’ve read in a few places an idea that if a cord has a breaking strength of 50lb, and a builder makes 10 wraps of that cord, then the joint has a breaking strength of 500lb. This is not true. If any of those wrappings is tighter than the rest, then it will bear the brunt of any force, and snap at 50lb. And then the whole wrapping comes undone.
Most artificial sinew is polyester. Which doesn’t stretch very well.
Of course, I used Hemp. (Enormously strong, growth rate isn’t improved by pesticides or fertilizers so farmers don't bother using it, replenishes super fast. But costly to process, extremely durable, and can’t be patented, so companies don’t market it to consumers much.) I dyed the Hemp with Walnut husks then painted it with Pine Tar. Hemp doesn’t stretch much either, probably less than polyester. Which is why every lashing on this boat is done at least twice. So if one breaks, the other is likely to get me to shore for repair.
A gratuitous, unnecessary shot for a dry building sequence. But it sure is pretty, and aids in understanding the beauty below her skin. Which is why we're all really here anyway.
Below we see the basket. Blocks in place of thwarts to hold her in position for the present. But thwarts are comin! Soon!
For thwarts, I began with a scrap board. Used it for a mock-up, to get my the compound angles.
Began roughing out thwart shapes with a bandsaw.
The thwarts are solid Ash. Each will be hollowed out into arcs with a thickness of 1/2in or so. I intend the front thwart to emulate the shape of a carrying yoke (though reversed), and a skate or bird. The rear thwart is modeled after a stag horn, someone leaning back on their elbows, and a backrest.
It doesn’t actually function as a backrest while paddling: it’s too far back for correct trim while underway. But a person can lean back on it and relax during scenery breaks.
Top view.
Refer to section on BreastBlocks for more on how to proceed from above rough, but from squared I pretty much used rotary tool, file, crooked knife, and sandpaper.
Underside.