DIGITAL SENSOR – SPEED LOG

Speed log is a digital sensor which measures the speed and distance travelled by a ship. It can also be said that speed logs are an important source for calculating the vessel’s performance. The sensor accuracy of a speed log depends on the calibration and the manufacturer. The unit used for expressing the speed of a vessel is knots.

Did You know?

Knots = Nautical Miles / Hours

There are five types of speed logs:

• Electromagnetic Log
• Doppler Log
• Impeller Log
• Pitometer Log
• Acoustic Co-relation Log

All the above logs measure speed through water except doppler log which measures speed over the ground.

There are several environmental factors that speed log measurements:

• WATER CLARITY; Velocity measurement in water depends on acoustic reflection from solid particles in the water, such as micro-organisms or suspended dirt.

STATE OF THE SEA: Any change in the state of the sea results in variable change in the speed of the vessel. This causes fluctuation in the measured speed.