MINE MK 10


The MK 10,  there were 3 Mods - Mod 3, 7 and 9 respectively, being sub, surface or aircraft launched respectively. It was classed as moored, magnetic, dip needle mine. The case length was 92.5 inches, had a negative buoyancy of 655 lbs. for the mine assembly, and a positive buoyancy of 195 lbs. in the water. Diameter was 20 and 13/16 inches, to fit standard 21 inch torpedo tubes. The anchor length was 28.5 inches and had 525 feet of 5/16 inch cable. The assembled weight was 1835 lbs. for the sub laid version and 1875 lbs. for the others (fin assembly or parapac added). It had a 410 lbs. TNT explosive charge. The firing Mechanism was the M5-1 (Red or Blue). Red was for the Northern hemisphere and Blue for Southern hemisphere. Those of us who worked them know them as very intricate mechanisms and recall such terms as the magnetic assembly, dampening system, counter-poise assembly, magnetic switch assembly, the famous clamp fuse (0.0063 nichrome wire), dow corning fluid, milligauss calculation, red and yellow dot identifiers, pawling errors, lat/long balancing weights, heading dependency tests, rocking tests, and upper/lower tests, outer/inner gimbals, and the mighty hemholtz coil to provide a testing environment. She was a pip. 
The respective Mods used the Extender Mk 14-0 (lock ball), Mk 14-1 (soluble washer), and Mk 14-2 (arming wire and safety-lock) to extend either a Mk1-1 or Mk 46-1 detonator and Clock Starter CS1-5 (lock ball), CS1-3 (soluble washer) and CS1-4 (arming wire and safety lock) as safety features. In addition the Clock Delay CD9-1 with a #4 short time replacement cam was used. The Mod 3 used a Dashpot anchor release, and the Mod 7 and 9 used an Mk 3-5 Hydrostatic Release mechanism for case and anchor separation. Planting depth was in waters 100 to 550 feet, with case mooring depths at 25 to 70 feet (40 optimum). Planting in waters with currents in excess of 4 knots seriously reduced mooring cable life to 2-5 months. Wave action in excess of 15 feet also affected the firing mechanism. Planting of the sub version was between 1 and 4 knots from bow tubes, any speed for surface version, and max 200 knots air speed for the aircraft laid version.  Curtsey of Toby Horn CDR RET.