Hi,
I have both my thumbs, but I may be able to help. I once broke my paddle and had an eskimo paddle as a spare, a new one, but I had left the loom too thick (Nick's book had said something about thicker shafts being more comfortable - not), for after several hours I could no longer use both my thumbs due to pain in them from the unnatural angle. To get home I still had some 30km to go and a head wind. So I placed both my thumbs on top of the loom and headed home. I made it in fairly heavy seas. I still have a residual tenderness in them years later. I now still often put my thumbs on top even on 29mm euro paddle shafts to give them a rest, so from experience, I think your friend should have no problems at all. Perhaps a finer loom would help your friend as he could then get a firmer grip on the paddle with his fingers alone.
JohnK

: Hello everyone,
: I have been asked by one of my friends to ask a question on
: building/paddling forums:

: Q: Will the lack of a left thumb affect ability to paddle with a
: Greenland paddle?

: Some background:
: My friend and paddling partner, who exclusively uses Greenland
: paddles with his handmade kayaks (Merganser, Outer Island), was
: working in his yard on a project when the power saw hit
: something in the wood, jumped and cut off his LEFT thumb, just
: above the knuckle at the base of the thumb. He has a small knob
: remaining and is concerned this will affect his paddling
: ability.

: Any answers appreciated and I will forward all replies to him over
: the next few days.

: Thanks!