Qualified guess: As the support ship presumably had some creature comforts missing on the replica viking ship, they probably rotated the crew - say, four days o

Qualified guess: As the support ship presumably had some creature comforts missing on the replica viking ship, they probably rotated the crew - say, four days on the replica, a day for a shower and some proper sleep on the support ship, another four days on the replica... Doesn't lessen the accomplishment in any way in my book if my guess turns out to be correct.