: I finished building a router jig to cut the rib mortises in the gunwales of
: the greenlander I have underway, what i did to get more sheer was to let
: the 2x4 im using sit out for the last two (very wet) weeks with about 60
: lbs. of scrap iron hanging from it this worked very well. I want to use my
: 7 1/2" freud thin kerf to split the 2x4 after i rout the mortises,
: this will take two passes on my table saw. Can any one point out at any
: problems I'm liable to run into? I've probably got 3" of curve in
: 16'. Thanks.
: Bob

with the ripping issue, both outfeed supports and finger bds at the blade will be important. Especially w/ the concave up, the board will want to go rotate sideways so higher outfeed will be important to minimize this potential lever arm. a high infeed(measured to the board curvature) could help too and keep the lowest point say somewhere around the blade. Similar for the concave down but especially the fingerboards here as it is naturally more stable. one for top, one for side.

however i bet that the main issue here is the question - what will happen to the board when it dries out? will it retain the curvature? no heat was used to modify the lignin bonds so what will happen? Looking at some lumber when it dries out, you'd never guess what it began as. i don't have the experience to suggest what'll really happen, but guess that you;d have to really plan the drying process in blocking - read time here.

my thoughts would be to rip it both ways so that each gunwale is in 2 pieces on on top of the other, dry out and glue w/ some modern epoxy or polyurethane glue to a specific shear curvature that you desire.

these are guesses somewhat, but i suggest that you don't know what will happen unless lots of racked and blocked drying time is spent. guess at 3 weeks super minimum. And blocked to a greater curvature than you want while it dries. Sounds like time to me.
-mick