(above) Atlantic 21: length overall 22ft 6in; beam 7ft 6in; draught, including engines, 2ft 6in; displacement I ton; maximum speed, 29 knots; range at full speed, 70 nautical miles.

The Atlantic 21, introduced in 1972, has a crew of three and launches from a carriage.

Her hull is ORP with an inflated neoprene sponson. photograph by courtesy of Keith Yuill Photographic.