Lit. "fogs, mists", (acc.?) pl. of the feminine noun 'þoka'.
> "Að öngu eruð þér því óbirgir"
> "You are unprovided with none (you have both),"
Yes, "you have both" (more literally "you unprovided with no such
thing" or "by no means are you unprovided with that").
Regarding the question in Gordon's notes of why they'd want wood, I
wonder if it was for repairs. I don't know if toredo worms were a
problem in such northern waters, but there were a menace to wooden
ships further south in the 18th century [ http://www.geocities.com/captsilversteele/ships/toredo.html ].