The idea is he has the wool available in the survival kit for wear underneath his windproof shell (the kayak jacket). Sorry I did not make that clear.

The only thing that touches my delicate body when on the water (or in as the case may be) is neoprene.... Provides that ever so nice buoyancy.

A real nice combination is a farmer john worn with a float coat. It works great for sea kayaking, but might not be quite so good for river work.