 Its complement at this time was a captain, two lieutenants and 103 other ranks.They were supplemented by a detachment of Wrens who operated a degaussing range established at Coalhouse Fort in 1943 under the name of HMS "St Clement".Outbound ships passed over submerged sensors which detected whether the steel in their hulls had been demagnetised to a sufficient extent to make them undetectable by German magnetic mines.