Used it in my first boat for the stringers. Works great, bombproof tough and durable. I run into a lot of rocks and have had no problems with it.
It is heavy yes, but you can use a smaller cross section. Also, anyone who thinks cedar isn't brittle should move to Alberta, it splits super easy in the dry climate up here, fir doesn't seem to do it as much.
Personally I think the best wood for a boat is whatever you can get your hands on for a good price locally.

: I just landed a job working for a lumber/timber company in Everett,
: WA. They produce 8 ft to 22 ft Douglas Fir planks that vary in
: width from 4 to 12 in and thicknesses of 1 to 6 inches. i also
: found out today they give employees a ridiculously good discount
: on wood as well... so my question is can Fir be used for strip
: kayaks and also do they make decent frames for skinned yaks as
: well?

: thanks all!