What should a vessel do if there is any doubt about potential risk of collision?

When a vessel is faced with uncertainty regarding the risk of collision, the prudent approach is to consider that a risk exists. This mindset is reflective of the key principles established by the COLREGs, which emphasize the importance of constant vigilance and the need to prioritize safety at sea.

By considering that a risk may be present, the vessel's master can take the necessary precautions to avoid a potential collision, which may include altering course or speed. This proactive stance is essential because overconfidence in the absence of danger could lead to complacency, and ultimately, to accidents.

The other options suggest actions that do not prioritize safety in uncertain situations. Proceeding at full speed and assuming there is no risk ignore the potential hazards that may be present. Meanwhile, taking immediate evasive action without prior assessment could lead to confusion or further risks, especially if the other vessel is also unsure of the situation. Thus, acknowledging the potential for risk allows for a more cautious and responsible navigation strategy.