leeboard

A board, or frame of planks, lowered over the side of a sailboat to lessen its leeway.

[…] on the port side a sofa bed was put up and fitted with a leeboard. On the starboard side a short seat with a folding cot above, which folded […]

Forward of the mizzenmast was an iron box in which the mainsheets worked, and to port and starboard were the leeboard winches, hand-worked.

Port, larboard (the side of a ship opposite starboard).

Even in complete reversals from starboard to leeboard in a high sea, no shocks, either electrical or mechanical, could be observed.

[…] because the leeboard side could be easily unrigged to avoid damaging the rigging, while the starboard side would be required to safely navigate the vessel.