What is the purpose of reducing speed to bare steerageway when navigating in restricted visibility?

Reducing speed to bare steerageway when navigating in restricted visibility primarily serves to prevent collisions. This practice allows a vessel to maintain enough control for maneuvering while also enabling the operator to react promptly to any potential hazards, such as other vessels or obstacles that may be difficult to see due to fog, rain, or other visibility impairments. At bare steerageway, the vessel is moving slowly enough to make steering easier, which crucially increases the chances of avoiding an accident.

While there are legal requirements regarding speed in various navigation situations, compliance is a secondary aspect of this speed reduction. Similarly, faster travel is counterproductive in restricted visibility as it increases the risk of striking unseen obstructions. Signaling other vessels is also important, but reducing speed specifically facilitates better navigation and collision avoidance rather than merely alerting others to your presence.