HAM Class Technical Data
Length: 106 ft 6 in , Beam 22 ft, Draft 5 ft 9 in
Standard Displacement: 120 tons and fully laden 164 tons
Propulsion: Twin shafts with Paxman 12YHAXM diesels of 550 bhp at 1000 rpm
Maximum speed: 14 knots or nine knots (17km/h) with sweeps streamed. A Paxman 12YHAZ engine provided power as the Pulse Generator for magnetic sweeping.
Complement: 2 officers and 13 ratings (potentially increased to 22 in wartime)
Armament: 1 x 40mm Bofors or 1 x 20mm Oerlikon
HAMs carried a lightweight version of the Oropesa sweep, capable of operating at depths as little as two fathoms (12 feet): useful for clearing beaches prior to an assault, but with the ever-present risk of anchoring by the sweep wires. Instead of otters and oropsea floats lighter “diverters” spread the sweep wires.
A similar lightweight MM11 magnetic loop sweep was carried, reminiscent of that used by the “Mickey Mouse” Motor Minesweepers of WW II.
Acoustic Hammer and Displacer sweeps were carried, but these significantly increased the draught of the vessels in their shallow water role.
VMT to Jack Worth's book "British Warships since 1945 - Part 4 Minesweepers" for much of the historical data in this section.