Electromagnetic log

An Electromagnetic Log, sometimes called an "EM Log", measures the speed of a vessel through water.

It operates on the principle that: 1 when a conductor (such as water) passes through an electromagnetic field, a voltage is created and 2 the amount of voltage created increases as the speed of the conductor increases.

The process is

  1. the EM Log creates an electromagnetic field.
  2. a voltage is induced in the water; the magnitude of the voltage varies depending upon the speed of the water flow past the sensor.
  3. the EM Log measures the voltage created and translates this into the vessel's speed through water.

Advantages
  • No moving parts
  • Less affected by sea growth than Pit sword

Disadvantages
  • Salinity and temperature of water affects calibration
  • Measurements affected by boundary layer, (water speed slowed down close to the hull by friction)
  • Provides boat/ship speed relative to water not ground. Current affects accuracy.
gollark: ... I mean, Discord?
gollark: Anyway, the e-ink ones (or at least mine) have an accursed non-Android Linuxy thing with a UI entirely done with web technology for some reason.
gollark: I think it's entirely the same except they have a different set of preinstalled apps to AOSP/Googlized Android, and Amazon services instead.
gollark: It's basically Android.
gollark: * e-paper, e-ink is a brand name.

See also


This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.