The first method was used as an approximation method for measuring vessel velocity in 1500-1600 AD, based on the idea of throwing a piece of wood into the water and controlling the speed of its movement away from the sea. And the second method is to design a device resembling a wooden chip hanging on a rope wrapped on a reel, and a temporal clock is a hourglass specified 30 seconds time, and the principle of the work of this device to connect the piece of wood rope Pulley m And then throw this chip into the sea behind the ship. The rope begins to disengage from the pulley at a speed that is directly proportional to the velocity of the vessel. The velocity of the vessel is calculated based on the calculation of the number of cord nodes that were launched at a given time period measured using the hourglass. Recent vessel speed measurement The node is still used today as a measure of vessel speed, but ultrasonic sensors or the so-called Doppler scale have been developed to facilitate the measurement process. The time period considered as divided in the speed calculation equation From 30 seconds to 28 seconds. Moreover, the speedometer was maintained in the registry, and marine distances were still measured by marine miles
