The stat I've most heard regarding the time to spin versus time to weave is that it took 7 spinners working full-time to keep one weaver busy. That does not specifically relate to cloth for sails, but just in general. Nat, who is doing the majority of the work to complete Louie's book has cited the Postrel book (which Louie wouldn't have had access to as it was printed after he passed away), so I'll pass this on to him to check.
The comment about the value of the sails comes thru in all the information Louie had gathered, not just among the Norse.
Again, thanks. I'm fortunate to have this way to ask questions and get info.