Which statement about radar on a vessel is true?

• A. It is optional equipment that may be ignored
• B. It should be used only during daylight
• C. It is illegal to rely on radar alone for collision avoidance
• D. It must be used to obtain early warning of collision risk

Answer: (D)

Radar provides early detection of potential collision risks by revealing other vessels even when visibility is poor or the target isn’t visible to the eye. In this framework, you’re expected to determine whether there is a risk of collision using all available means, and radar is a key tool for obtaining that early warning. The range and bearing information radar supplies lets you track how a target is approaching, whether its bearing is changing in a way that could lead to a collision, and how fast it’s closing, so you can decide on timely avoidant action. That makes the statement about radar being used to obtain early warning of collision risk the best choice because it captures radar’s essential role in proactive safety. The other ideas don’t fit: radar isn’t optional equipment; it should be used in all conditions, not just daylight; and while you shouldn’t rely on radar alone for collision avoidance, its early-warning function is the fundamental reason to use it.