Did some googling.
you can use that same string to determine the position of the slots in the lower chanel.
You may discover that the slots in the upper chanel need some tinkering to get enough space to set them on the correct angle
Nope: wood is not metal. There is more to gain from prebending your wood, in order to prevent stress. (Using moisture/heat/and sometimes a template to get the correct bend)
After assembling your hull will be (at least almost) symmetrical, so that remaining stress will more or less ‘even out’.
As far as my knowledge goes: after carefully bending and fitting your planks, they should attach with relatively little stress. Therefore, once you glue them (both to the bulkheads and their neighbors) there is no need, and no method for stress relieving. In fact: any excessive heat/moisture after building your hull will damage your work.
Jan
