Similar to other underwater weapons, the Japanese did not spend much energy on mines prior to World War II. This was mainly because mines were considered to be "defensive" weapons and so were not of value to an "offensive" minded Navy.
Almost all Japanese mines were of Hertz Horn construction. No magnetic (influence) mines were developed although a number of British A Mark I - IV mines captured at Singapore were laid off Balikapan in 1945. A shore-controlled mine with an acoustic detector was developed late in 1944 and 144 of these were laid across the entrance to Tokyo Bay.
As mentioned above, the Japanese used Hertz Horns almost exclusively. Each horn contained acid. Contact with the horn broke open the acid container which energized a battery and exploded the mine.
During the war a variation was developed that replaced the acid horns with switches that activated when a ship hit the horn. By definition, horned mines were short ranged weapons and fields needed to be densely packed to be effective against shipping.
The Japanese used a variety of explosives in their mines.
| Name | Composition |
|---|---|
| Shimose | Picric Acid |
| Type 88 | 66% ammonium perchlorate, 16% ferro-silicon, 12% wood pulp, 6% oil. It was believed that silicon carbide assisted in the uniform propagation of a detonation wave through loosely packed powder. |
| Type 97 | 60% TNT, 40% hexanitrodiphenylamine (HND). |
| Type 98 | 70% trinitroanisole, 30% HND. |
| Type 1 | 81% ammonium picrate, 16% aluminum, 2% wood pulp, 1% oil. |
Unknown. I would appreciate any information in this regards.
| Total Mass | 1,146 lbs. (520 kg) |
|---|---|
| Explosive Charge | 183 lbs. (83 kg) |
| Trigger/Fuze | 4 Hertz Horns |
| Total Mass | 2,549 lbs. (1,156 kg) |
|---|---|
| Explosive Charge | 474 lbs. (215 kg) Shimose |
| Trigger/Fuze | 4 Hertz Horns |
| Total Mass | 2,381 lbs. (1,080 kg) |
|---|---|
| Explosive Charge | 441 lbs. (200 kg) Shimose |
| Trigger/Fuze | 4 Hertz Horns |
| Total Mass | 1,984 lbs. (900 kg) |
|---|---|
| Explosive Charge | 441 lbs. (200 kg) Shimose |
| Trigger/Fuze | 6 Hertz Horns |
| Total Mass | 2,116 lbs. (960 kg) |
|---|---|
| Explosive Charge | 397 lbs. (180 kg) Shimose |
| Trigger/Fuze | 4 Hertz Horns |
| Total Mass | 1,543 lbs. (700 kg) |
|---|---|
| Explosive Charge | 220 lbs. (100 kg) Type 88 |
| Trigger/Fuze | 4 Hertz Horns |
| Total Mass | 1,543 lbs. (700 kg) |
|---|---|
| Explosive Charge | 220 lbs. (100 kg) Type 88 |
| Trigger/Fuze | 7 Hertz Horns |
| Total Mass | 1,543 lbs. (700 kg) |
|---|---|
| Explosive Charge | 220 lbs. (100 kg) Type 88 |
| Trigger/Fuze | 9 Hertz Horns |
| Total Mass | 1,565 lbs. (710 kg) |
|---|---|
| Explosive Charge | 243 lbs. (110 kg) Type 1 |
| Trigger/Fuze | 4 Hertz Horns |
| Total Mass | N/A |
|---|---|
| Explosive Charge | 88 lbs. (40 kg) Type 88 or Type 1 |
| Trigger/Fuze | Hertz Horns; 3 |
| Total Mass | N/A |
|---|---|
| Explosive Charge | 88 lbs. (40 kg) Type 88 or Type 1 |
| Trigger/Fuze | 4 Hertz Horns |
| Total Mass | 298 lbs. (135 kg) |
|---|---|
| Explosive Charge | 110 lbs. (50 kg) Type 97 |
| Trigger/Fuze | Switch horns; 3 |
Drifting mine. Deployed using a parachute.
| Total Mass | 238 lbs. (108 kg) |
|---|---|
| Explosive Charge | 121 lbs. (55 kg) Type 88 |
Attached to anti-submarine nets. Fired when the tension on the net exceeded a set value.
| Total Mass | 2,866 lbs. (1,300 kg) |
|---|---|
| Explosive Charge | 1,102 lbs. (500 kg) Type 88 |
A shore-controlled acoustic mine.
Japan currently uses mines either identical to, or externally similar to, USA types. They are designated in a K series during their development cycle. They receive type numbers when placed in service.
"Naval Weapons of World War Two" by John Campbell
"US Naval Weapons" and "The Naval Institute Guide to World Naval Weapon Systems 1991/92" both by Norman Friedman
21 June 2008 - Benchmark
17 February 2018 - Converted to HTML 5 format