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A chip log, also called common log, [1] ship log, or just log, is a navigation tool mariners use to estimate the speed of a vessel through water. The word knot, to mean nautical mile per hour, derives from this measurement method.
Secondly, the surveyor can use a sound velocity probe that can be lowered into the water in the area to be surveyed to measure the actual speed of sound. This has the advantage of being quicker than a bar check and it can be performed when there is boat motion due to swell and sea, although any draft offset of the vessel is not identified using ...
This unit uses a mercury-based manometer to measure the difference in static and dynamic water pressure. Pitometer logs (also known as pit logs) are devices used to measure a ship's speed relative to the water. They are used on both surface ships and submarines. Data from the pitometer log is usually fed directly into the ship's navigation system.
Chip log and sand glass serve to measure the ship's speed through the water.; Sounding line used to measure the depth of the water and to pick up samples from the bottom.; Drift meter optically measures the effects of wind on an aircraft in flight.
The indicated speed must never be less than the actual speed, i.e. it should not be possible to inadvertently speed because of an incorrect speedometer reading. The indicated speed must not be more than 110 percent of the true speed plus 4 km/h (2.5 mph) at specified test speeds.
In long-distance navigation through the open ocean, the sandglass or "glass" used to measure the time was a tool as important as the compass (which indicated sailing direction, and so ship's course). [ 2 ] [ 3 ] Filled with the amount of sand suitable for measuring a lapse of half an hour, each time the sand emptied was also called a "glass ...
An aeroplane can stall at any speed, so monitoring the ASI alone will not prevent a stall. The critical angle of attack (AOA) determines when an aircraft will stall. For a particular configuration, it is a constant independent of weight, bank angle, temperature, density altitude , and the center of gravity of an aircraft .
A Doppler velocity sensor (DVS) is a specialized Doppler radar that uses the Doppler effect to measure the three orthogonal velocity components referenced to the aircraft. When aircraft true heading , pitch and roll are provided by other aircraft systems, it can function as a navigation sensor to perform stand-alone dead reckoning navigation ...