A professional who observes vessels passing inland-waterway checkpoint, using binoculars, to verify identity and ascertain speed and direction.

• Telephones observations to designated control point, such as drawbridge or lock station.
• Reports movements of overdue vessels to estimate arrival time at specified points along waterway.
• Notifies waterway officials or other authorities of accidents, distress signals from passing vessels, obstructions, and other unusual conditions observed from checkpoint.
• Records observations in log.