Vessel required to have an Electronic Plotting Aid (EPA) must have a device to indicate the __________.

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

To calculate the true motion of targets, an EPA must process the vessel's own motion. Per 46 CFR and IMO performance standards, the device requires a continuous input of the vessel's speed—either through the water via a log or over the ground via GPS—to accurately determine relative and true vectors.