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A chip log consists of a wooden board attached to a line (the log-line ). The log-line has a number of knots at uniform intervals. The log-line is wound on a reel so the user can easily pay it out . Over time, log construction standardized. The shape is a quarter circle, or quadrant with a radius of 5 inches (130 mm) or 6 inches (150 mm), [1 ...
Electromagnetic log. An Electromagnetic Log, sometimes called an "EM log", is an electronic sensor which measures the speed of a vessel through sea water. Like many other technologies, its name derives from the traditional chip log. It makes use of Faraday's law of induction by measuring the EMF induced in water moving through a magnetic field ...
Impeller log:A variation of this approach is known as a patent log, which is towed from the stern of a ship. The patent log includes a mechanical register that counts the log's rotations as it is being towed. The patent log was invented in 1688 by the English instrument maker Humphry Cole. The patent log is also known as a screw log or taffrail ...
A logbook (a ship's logs or simply log) is a record of important events in the management, operation, and navigation of a ship. It is essential to traditional navigation, and must be filled in at least daily. The term originally referred to a book for recording readings from the chip log that was used to estimate a ship's speed through the ...
The wind profile power law relationship is. where is the wind speed (in metres per second) at height (in metres), and is the known wind speed at a reference height . The exponent ( ) is an empirically derived coefficient that varies dependent upon the stability of the atmosphere. For neutral stability conditions, is approximately 1/7, or 0.143.
In probability theory, a log-normal (or lognormal) distribution is a continuous probability distribution of a random variable whose logarithm is normally distributed. Thus, if the random variable X is log-normally distributed, then Y = ln (X) has a normal distribution. [2] [3] Equivalently, if Y has a normal distribution, then the exponential ...
The knot ( / nɒt /) is a unit of speed equal to one nautical mile per hour, exactly 1.852 km/h (approximately 1.151 mph or 0.514 m/s ). [1] [2] The ISO standard symbol for the knot is kn. [3] The same symbol is preferred by the Institute of Electrical and Electronics Engineers ( IEEE ), while kt is also common, especially in aviation, where it ...
A logarithmic scale (or log scale) is a method used to display numerical data that spans a broad range of values, especially when there are significant differences between the magnitudes of the numbers involved. Unlike a linear scale where each unit of distance corresponds to the same increment, on a logarithmic scale each unit of length is a ...