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| GERMAN UNDERWATERS ORDNANCE MINES |
| Chapter 4 - CONTACT AND MOORED INFLUENCE MINES |
| THE FM MINES |
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FMC Mine. The FMC Mine was developed and completed between 1926 and 1928. It was a surface-laid, moored, contact, chemical-horn mine using the normal plummet-type anchor and containing a heavier charge than the FMB Mine. |
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Details. The FMB and FMC both used a wire cable mooring and a spring buffer; how-ever, only the FMC took depth by plummet. Mooring tension pulled out the arming spind-le, closed the mooring safety switch and the "A-E" switch, and tripped the booster-re-lease lever to arm the mines. The "A-E" switch in these mines served only to open or close a switch in the horn circuit. The FMB had two lifting eyes welded to the upper he-misphere. FMC had one lifting eye welded to the upper hemisphere and three anchor-se-curing lugs; one on the upper hemisphere and two on the lower hemisphere. There are two designations for the FMB mine; FMB and FMB (35). These differs only in the weight of explosive. 28 pounds and 44 pounds, respectively. The FMB and FMC differ from each other as follows: |
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FMB Mine |
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Diameter of mine case |
26 in. |
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Weight of charge |
28 lb. or 48 lb. |
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Number of horns |
5; one, in center of upper hemisphere; 4 equally spaced around upper hemisphere |
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Depth setting |
preset |
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Minimum depth setting |
---- |
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Mooring cable |
25 ft. long |
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FMC Mine |
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Diameter of mine case |
30 in. |
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Weight of charge |
88 lb. |
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Number of horns |
same as FMB |
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Depth setting |
1 ft. to 15 ft. |
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Minimum depth setting |
13 ft. plus length of depth-setting mechanism |
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Mooring cable |
160 ft. long - 7/16-in. diameter |
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The only self-disarming device is the mooring safety switch, which is designed to dis-arm the mine by opening the firing circuit upon release of mooring tension. |
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Figure 27 – FMC Mine Afloat |
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Figure 28 – FMB Mine |
Figure 29 – FMC Mine |
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