: I'm about to start a boat based on the Greenland Kayak In Robert Morris’
: book. My choices for gunwales are pretty much Red Cedar or Douglas Fir. My
: preference is for the cedar, but I am concerned about strength. Any
: advise? Thanks

I've talked to a few people about gunwale woods and both fir and cedar will work fine. Cedar gunwales will need to be a bit taller (as opposed to thicker) than fir gunwales, since it's relatively flexible. You gain much more stiffness by increasing the height of the gunwales than by increasing the thikness. Cedar should save you a lot of weight vs. fir. I used fir for my keel and chine stringers and found it to be a bit too stiff for the chines. It was fine for the keel. I suspect that fir gunwale boards would have to be rather short in order to be flexible enough. I used yellow pine for mine (I won't do that again) and reduced the height to 2 3/8" to compensate for it's stiffness. That would probably be a good idea with fir.

You can reduce the thickness, but personally, I like having 1/4" of material on either side of the rib mortises. I guess it's just a security thing.

One thing to consider is the way the wood is cut vis a vis the way you plan to make your gunwale boards. Around here, CVG fir is the norm, so making gunwale boards from a fir 2x4 (Morris' method) is feasible. Cedar, on the other hand, is more available here in a flat sawn configuration, so cutting the gunwale boards out of a 1x8 with symmetric grain is easiest with cedar.

If white pine is available in your area, don't dismiss it as a gunwale wood. It's in between cedar and fir in weight, stiffness and strength. My next SOF boat will have either red cedar or white pine gunwales.