Vessels required to have an Automatic Radar Plotting Aid must have a device to indicate the __________.

Correct Answer: Option A — speed of the vessel over the ground or through the water

IMO and SOLAS performance standards for Automatic Radar Plotting Aids (ARPA) mandate continuous input and display of own ship's speed. Systems must incorporate devices to automatically or manually input speed through the water or over the ground to calculate true target vectors accurately.