High Quality Content by WIKIPEDIA articles! Prison hulks were decommissioned ships that authorities used as floating prisons in the 18th and 19th centuries. They were especially popular in England. The term "prison hulk" is not synonymous with the related term, convict ship. A hulk is a ship that is afloat, but incapable of going to sea, whereas convict ships are seaworthy vessels whose purpose was to transport convicted felons from their place of conviction to their place of banishment.