DEGAUSSING COIL INTERFERENCE.
Research and development rept.,
NAVY MARINE ENGINEERING LAB ANNAPOLIS MD
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Because of their ferromagnetic properties, steel-hulled ships distort the ordinarily uniform earths magnetic field. To avoid detection by magnetically-triggered mines, naval vessels have installed degaussing coils to generate magnetic fields opposing this distortion. The degaussing coils are arranged to compensate for the ships influence and restore a relatively uniform field some distance beneath the water surface. Certain shipboard instrumentation can be seriously affected by these degaussing coil fields. To alleviate this problem, shipboard locations exhibiting low degaussing coil field strengths should be predetermined to ensure a safe environment for such sensitive instruments. Initially the degaussing coil system was simulated by a digital computer for the purpose of computing system magnetic field values for the air-core case excluding effects of ferromagnetic material. A least mean square method was used to ascertain the degree to which air-core data could be used to predict the actual shipboard values. Results of this analysis indicate that shipboard magnetic fields cannot be predicted to any useful degree of accuracy by means of simple proportionality with the air-core data. Author
- Marine Engineering
- Electricity and Magnetism