Sabreman's point about traditional proven methods is valid.. in the long run shortcuts don't pay off. As someone once said, if you don't have time to do it right, how are you going to find time to do it a second time?
We've done this sort of job several times, always using some form of furring strips as a basis for the ceilings. Bruce Bingham's "The Sailor's Sketchbook" shows a variation, glassing some aluminum tubiing in place and screwing the wood to that after drilling/tapping. Lots of work, true, but there for the long haul. The nice thing about the tubing is that once bent it will retain its shape, unlike most wood that will try to go back to straight and can require some innovative clamping techniques while the glue cures. Kerf-cut plywood strips are another option.
It is a very effective and properly nautical look, though, once done properly.
1984 Fast/Nicholson 345 "FastForward"
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)