Ham class minesweeper

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Ham-class minesweeper
General characteristics
Displacement:	120 tons standard / 164 tons full
Length o/a :	106 feet 6 in (32.5 m) except third sub-group, 107 feet 6 in (32.8 m)
Length p/p :	100 feet (30.5 m)
Beam:	26- group; 21 ft 4 in (6.5 m) 27- group; 22 ft (6.7 m)
Draught:	26- group; 5 ft 6 in (1.7 m) 27- group; 5 ft 9 in (1.8 m)
Propulsion:	2 shaft Paxman 12YHAXM diesels, 1,100 bhp (820 kW)
Speed:	14 knots (26 km/h)
Range:	15 tons diesel fuel, ?
Complement:	2 officers, 13 ratings
Armament:	1 x 40 mm Bofors / 20 mm Oerlikon gun

The Ham class was a class of inshore minesweepers (IMS), known as the Type 1, of the British Royal Navy. The class was designed to operate in the shallow water of rivers and estuaries. It took its name from the fact that all the ship names were British place names ending in -"ham". The parent firm who were responsible for supervising construction was Samuel White of Cowes, Isle of White.

The class consisted of 93 ships, launched between 1954 and 1959. HMS Inglesham (M2601) was the first. They were built in three slightly different sub-groups, the first sub-group being distinguished by pennant numbers beginning with 26- and the second and third sub-groups being distinguished by pennant numbers beginning with 27-. The 26- group were of composite construction (wood and non-ferrous metals and the 27- group were all-wooden, of which the third sub-group differed by having a prominent rubbing strake around the hull and slightly enlarged dimensions.

The vessels displaced 164 tons fully laden and were armed with one 40 mm Bofors or 20 mm Oerlikon gun. They were 32.5 metres long overall by 6.4 metres beam. The construction was of wood to minimise magnetic signature. The crew complement was 15, rising to 22 in wartime.

The engines of this class were Paxman diesels, some of which were built under licence by Ruston and Hornsby of Lincoln. Each vessel had: two 12YHAXM (intercooled) for main propulsion, rated 550 bhp at 1,000 rpm, plus one 12YHAZ for pulse generation. Maximum speed was 14 knots (26 km/h) dropping to 9 knots (17 km/h) when mine sweeping.

The class shared the same basic hull as their minehunting counterpart the Ley-class and the Echo-class inshore survey craft.