Vikings were great sailors but did not use and especially did not make maritime maps
The Dutch did and I was a little bit surprised until now that nobody reacted on the strange explanation of “Kattegat”
Kattegat has nothing to do with a cat’s ass or that cats on ships always climb away in the smallest places.
If the Dutch indicate on their maritime maps that a specific passage is a “Kattegat” they warn every sailor that that passage is only for flat bottom ships and they advice every captain to use the activity of “katten” i.e you bind a rope on your anchor throw your anchor out and bind the securing rope on the back of your ship. Just before your ship will hit bottom the anchor will claw itself into the ground beneat it and than stop the movement of the ship avoiding further damage.