10 Questions
What principle does the Pressure Tube Log operate on?
Pitotmeter Principle
What happens to the pressure in the tube if it is held stationary?
Remains constant (static pressure)
What does Pitot's Law relate dynamic pressure (p) to?
The square of the ship's speed (v)
How is static pressure's effect eliminated in order to get accurate dynamic pressure readings?
By installing a second tube (static pressure intake tube)
Where is the static tube located in the practical installation of the speed log?
Opening in the ship hull
How are both static and dynamic pressures transferred to the speed indicator on the ship's bridge?
Via air controller and strainer valves
In a Pitot system installation on a vessel, what is the purpose of the seacock arrangement and valve control?
To prevent water intake
What is a limitation of the EM Log system?
It has a zero error that needs correction
How does the EM Log determine the vessel's speed?
By creating an electromagnetic field and measuring the induced voltage
How is speed indication affected in Pitot's Law as the ship's speed increases?
It increases non-linearly, following the square of the speed
Learn about the three types of speed logs used on commercial vessels to measure the speed of a moving vessel, including how they operate based on different technologies and principles such as electro magnetic induction, Doppler Effect, and water pressure.
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