Which meaning of 'bear' befits 'bear off' below?
Please see the titled question, and in the screenshot beneath of the OED page for 'berth'. The punchline's the red underline in the screenshot:
A nautical term of uncertain origin: found first in end of 16th cent. Most probably a derivative of bear v.1 in some of its senses: see especially sense 37, quot. 1627, which suggests that berth is = ‘bearing off, room-way made by bearing-off’; compare also bear off in 26 b.
Etymonline lacks details.