Almost everyone knows that the speed of ships is measured in knots. This standard has been around for many, many years. Why do sailors use such a system for determining the speed of an object?
First, a little history. When navigation was just in its infancy, people did not have instruments that would help them navigate as accurately as possible in the endless water space. Many preferred to walk along the coast so as not to get lost.
Later, people were helped by geographic coordinates. With latitude (position relative to the equator), the sailors figured out relatively quickly, they were helped by the North Star. But with longitude (position relative to the Greenwich meridian) they had to tinker.
Sailors had to determine the distance that they covered from a point with a known longitude for a specific period of time. For this, a sector lag was invented. The name of the invention comes from the Dutch log - distance.
His first examples were an ordinary log or board with an attached cable - a line. During the movement of the ship, this device was thrown overboard, and due to its design, it occupied a perpendicular position relative to the direction of travel of the floating craft.
The sailor's task was to determine the length of the line that went overboard in a fixed time, for example, a minute. For this, knots with the same distance were knitted on the cable, and then their number was counted. The distance between the nodes was set in advance so that their number reflected the speed of the vessel. This is how the unit of measurement of speed got its name.
The log is also present on modern ships - it is a device with flat blades that rotate while in motion. They trigger a mechanism that determines the speed of the vessel.
Promotional video:
Now to the numbers. A nautical knot is a unit for determining the speed at which an object travels a nautical mile in one hour. This standard is used in many countries around the world and equals 1852 m3 / h.
A nautical mile is one minute long of a meridian arc, that is, 1/21600 of the meridian arc length. Due to the shape of our planet, this value fluctuates - at the poles it is 1861.6 meters, at the equator - 1842.9 m.
The unified mile is approximately equal to the value of the length of the minute of the meridian degree at latitude 45º - 1852.2 meters.
The speed of ships is measured in knots, as this value is generally accepted, complies with international standards and helps sailors to better understand each other.
The correct use of this term is as follows: the ship is at full speed 15 knots. Incorrect: 15 knots per hour.