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| GERMAN UNDERWATERS ORDNANCE MINES |
| Chapter 7 - SUBMARINE-LAID MINES |
| THE SM MINES |
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The SMA Mine. The SMA moored, influence mine series was designed for laying by the type VII-D and X-B submarines. These submaries were fitted with special shafts to acco-modate this type of mine. The design of the SMB was undertaken in 1937 at low priority. This mine was primarily intended for use in American waters. The SMC was completed in 1944 and was ready for operational use prior to the end of World War II. |
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Possible Units |
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1. M 3, A 7 |
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2. M 4, AE 1 |
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Figure 97 – SMA Mine Afloat |
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Description of Case |
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Shape |
Two hemispheres, joined by a 5-in. cylindrical section |
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Material |
Aluminum (KSS) |
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Diameter |
46 in. |
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Length |
56 in. |
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Charge |
750 lb. block-fitted hexanite |
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Description of External Fittings |
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Cover plate |
19-in. diam., in center of upper hemisphere, flush type, secured by 18 bolts |
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Base plate |
15-in. diam., in center of lower hemisphere, lap-fitted se-cured by 18 studs; fitted with straight-shank mooring spindle and detonator strongback |
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Lifting eyes |
Two, 180° apart on upper hemisphere, 24-1/2 in. from center |
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Anchor-securing lugs |
Three, angular-shaped, 120° apart on lower hemisphere, 29-1/2 in. from center. |
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Positioning lugs |
Two, fin-shaped, 180° apart on cylindrical mid-section |
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Figure 98 – SMA Mine – Cross Section |
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Operation. The mine took depth by a loose-bight hydrostat system. Morring tension pulled out the mooring spindle, tripped the booster-release lever, and released the lock-ing balls from the clock-starting spindle. Water pressure depressed the clock spindle at a depth of 15 feet, starting the clock. The clock ran off its delay period, and the unit star-ted its testing cycle. |
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The only self-disarming device was the 80-day clock which was designed to scuttle the mine if the clock stopped at any time prior to completion of its set period or upon completion of its set period. |
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Figure 99 – SMA Mine with Anchor |
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