(left) Watson: length overall 46ft 9in; beam 12ft 9in; draught 4ft 4in; displacement 23 tons; maximum speed, over 8 knots; range at full speed, 200 nautical miles. The 46ft 9in Watson, introduced in 1947, launches down a slipway or lies afloat. She has a crew of seven and her hull is built of wood.

photograph by courtesy of Colin Watson.