Reasonably knot free to me means I will not lose a large amount of wood when I scarf out all the knots. The problem is all the long boards at my local HD are so knotty they are useless. But 8 footers are often good enough quality that the most important strips are made from only two pieces. The less important stuff could be made from three or even four pieces. Of course all of this requires very good scarf joints.
Most of the designs I looked at just used 1' nominal stringers. But a Greenland boat needs two fairly long wide boards to do sheer planks that bend properly. One piece sheer planks are ideal but planks scarfed from two pieces can work if you have the patience to make it work.
Morris lives in the center of one of the greatest softwood lumbering centers in the world. He can afford to be picky. We live in an area that still produces a lot of hardwood. Some of it can be used although none of it will be ideal.
Wolfgang Brinck, who wrote the definitive book on building Aleutian baidarka
replicas, built his boats in Milwaukee and used whatever he could get locally. Of course, he used green willow shoots for his ribbing which will never be part of anything I paddle.
The one wood we have access to that is light enough and clear enough to work is basswood. But it's not rot resistant to any degree and would require a good finish and a lot of attention to make it last.

: Charlie said: And Bill said: That's very interesting. My knowledge of SOF
: kayak building comes from two books (Cunningham's "Building the
: Greenland Kayak" and Morris's "
: Building Skin-on-Frame Boats") and no practical knowledge whatsoever. As
: I recall, both said that kiln dried was bad - even for the long members
: (due to damaged cells walls due to overheating I think), and at least one
: said that western red cedar was bad (due to brittleness, I think).

: This is baloney? How "knot free" is reasonably knot free?