Re: Cutting centerboard slot
For some reason I can't find Bob Smalser's excellent "web article" on restoring the gunning dory, but that's what I used when cutting my CB slot in my restored Chamberlain dory skiff.
Bob's recommendation for using epoxy and glass cloth in the slot are also good ones -- this is where the CB rubs on the CB slot, and also where the water can get in between the false bottom (if you have one), the bottom, and the CB case/bottom plank joint. Whatever you use, seal this well!
I used a flexi sealant (Vulkem116) to join the CB case to the bottom, but in retrospect could have gone with epoxy or another harder adhesive.
If you don't have or like using a plunge router, you can tack similar guides on the bottom for a circular saw cut. Can't do the ends of the slot that way, but a handsaw and/or chisel should finish them just fine.
"The enemies of reason have a certain blind look."
Doctor Jacquin to Lieutenant D'Hubert, in Ridley Scott's first major film _The Duellists_.