*portoise*

n. [ Perhaps fr. OF. porteis portative, portable. ] (Naut.) The gunwale of a ship. [ 1913 Webster ]

To lower the yards a-portoise, to lower them to the gunwale. --
To ride a portoise, to ride an anchor with the lower yards and topmasts struck or lowered, as in a gale of wind. [ 1913 Webster ]