The  sixth rates were a series of six ships built to his 1805 design. Perhaps his smallest vessels were the two Placentia-class sloops of 42 tons burthen, which he designed for coastal patrol duties off Newfoundland.
A series of six warships was built in accordance with his 1805 design. He also created two smaller vessels, the Placentia-class sloops, weighing around 42 tons, intended for coastal surveillance missions near Newfoundland.