The author is Wolfgang Brink. I know several people who have built Brink Greenland boats and I paddle with one that built his from the Instructable ... the author is fine and his boats are fine. If anything has been omitted in the instructable IMO it's just an oversight ... and there are plenty of other sources that can be used to fill in any gaps.

Ken Blanton

I have never made a Greenland style boat. Normally I would avoid Instructables like the plague. This doesn't look like a bad author.
I'd be concerned if you can't find the sizing on a major piece of structure.
Check out Tom Yost's site with SOF fuselage style boats. There are Greenland style there. www.yostwerks.com/WoodSOFMain.html

Good luck