water. The first three boats were built with wooden hulls and were respectively , and long, the extra length due to a rounded transom. All differed in superstructure design, 52-01 having a raked back superstructure front with the flying bridge at the after end. 52-02 introduced forward raked wheelhouse windscreens, had a unique wheelhouse side window pattern and retained the aft mounted flying bridge. On 52-03, the flying bridge was moved to the forward end of the wheelhouse, the front of which was rounded. From 54-04, the forward flying bridge was standardised and the forward raked wheelhouse windscreens were reintroduced. The side windows were recessed from the superstructure sides. 54-04 had a Glass Reinforce Plastic hull and this was standardised for future boats. 54-04 to 54-07 retained the rounded transon but from 52-08 a square transom was reintroduced. The final external change came with 52-11 which had flush sided forward wheelhouse windows and this was a feature of all subsequent boats. In 1986 52-030 (ON 1100) became the only steel-hulled Arun. It was regarded as the best of the class for seakeeping, although the slowest. The GRP hulls were moulded in blue material in the outer skin. After a while it was found that water was accumulating in the fibreglass which added up to two tons to the weight. The boats had the coloured layer stripped off and replaced by a new one made with clear gel which reduced the amount of water absorbed. The large watertight cabin gave it self-righting capability. Two survivor cabins are situated below decks where first aid and emergency equipment is stowed. The hull is divided into 26 watertight compartments as protection against sinking should it be holed. There is also a flying bridge above the main cabin with an auxiliary steering position which can be used when additional height or visibility is required during an operation. The boat won a Design Council award in 1982. Two Caterpillar D343 diesel engines were fitted to boats up 52-14, subsequent boats being fitted with two Caterpillar 3408TA . Fuel tanks have capacity which gives an operating range of . RNLI fleet Other fleets Australia Canada Ten boats were built for the Canadian Coast Guard. They were all built in Canada by Industrie Raymond Ltée of Sept-Iles, Quebec; East Isle Shipyard Ltd. of Georgetown, Prince Edward Island; Hike Metals & Shipbuilbing Ltd. of Wheatley, Ontario, with aluminium hulls