Stop on board (5,2)

I believe the answer is:
heave to
This could be a double definition.
'stop' is the first definition.
(I've seen this before)
'board' is the second definition.
Both the definition and answer are verbs in their base form.
Perhaps they are linked in a way I don't understand?
'on' is the link.
Can you help me to learn more?
(Other definitions for heave to that I've seen before include "stop at sea" , "Of ship, stop without anchoring or mooring" , "come to a stop for navy" , "(Of a sailing vessel) stop moving" .)