(right) Arun: length overall 52ft or 54ft; beam 17ft; draught 5ft; displacement 31 tons; maximum speed 18 knots; range at full speed, 200 nautical miles. The Arun, introduced in 1971, has a crew of six; she lies afloat. Hulls of the first three boats of the class are built of wood, and hulls of subsequent boats of GRP..