Built in Boston for Lord Percy, 1774, with one centreboard.
Built at Deptford, 1789, with three sliding keels.
The Admiralty in 1790 A.D. had a revenue cutter called the 'Trial,' built with three sliding keels. The report was most satisfactory, and a note on their application describes—
Use of fore keel in tacking and laying to.
Use of keels on a wind, raised or depressed according as necessary to assist helm or gain the wind.
Use of after keel, in wearing or scudding in a gale of wind.
Keels hove up going over shoals or before the wind.