Maybe this is a solution to the knarr security problem?
A liftable (or taking up a lot of inventory space) steering wheel that you can remove from the helm of the ship and put back on if you want to travel seems to me like a good security alternative to a key.
I think it should be craftable for spares and stealing knarrs, but it shouldn't be too easy to make, it should at least require metal and an anvil to build one. Also thieves loading up a knarr or a rowboat with steering wheels pretty much cancels all security such a wheel might have, so maybe they shouldn't fit in boats?
A little pole you could attach it to would be nice as well.
with any luck if this gets implemented it will lead to the knarr warrs
EDIT: changed the title after reading the rules