Page 38 - Electronic Navigation Cyber Book
P. 38
ELECTRO MAGNETIC LOGS
This type of log consist of
1. Master Indicator
2. Preamplifier
3. Sensor
Operations
The sensing of speed makes use of law of electromagnetic induction.
When the ship moves, the water passing through the hull acts as a
conductor.
The magnetic field is produced by a solenoid, installed in such a way as
to allow the field to extend into water.
This produces an EMF (electromagnetic force), which is measured and
converted into the speed of vessel through the water.
Principle
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