When two sailing vessels are in proximity and you can’t determine which vessel has the wind on which side, the safe course is to keep out of the way of the other vessel. The reason is that the rules require the vessel on port tack to yield to a vessel on starboard tack, but if you can’t tell the other vessel’s wind side, you can’t be sure who has the right of way. By keeping out of the way, you avoid a potential collision and allow the other vessel to maneuver if necessary. Actions like turning abruptly, speeding up, or stopping do not address the uncertainty and can create additional risk, whereas easing off or altering course to pass well clear fulfills the obligation to take early and substantial action to prevent a collision.

Sound signaling in COLREGS communicates maneuver intentions in close quarters. In a narrow channel, two long blasts followed by two short blasts tells the other vessel that you intend to pass on its port (left) side. The longer blasts grab attention and indicate a definite maneuver, while the shorter blasts specify the side of passing. Hearing this, the other vessel should hold course and speed or adjust as needed to give safe clearance for the pass on the port side. This pattern is specific to port-side passage; other sequences indicate different intentions and do not convey the same meaning.

The sternlight identifies the rear of the vessel and is designed to cover a specific arc behind it. It must be visible from directly astern and extend 67.5 degrees to each side of the stern, giving a total behind-arc of 135 degrees. This arrangement ensures other vessels behind you can reliably see the sternlight without the light extending too far forward and causing confusion with the side or forward lights. So, the correct degree on each side is 67.5°.

In restricted visibility, you must proceed at a speed that allows you to take proper and effective action to avoid a collision. Hearing a fog signal forward of your beam means another vessel could be ahead in the area you can’t clearly see, so you don’t yet know the risk. Reducing to bare steerageway—the minimum speed at which you can still control the vessel and maneuver—keeps you able to observe, react, and alter course or speed if a danger emerges. Staying at full speed would give you less time to respond and less maneuvering room if the other vessel’s position or actions become clearer. Stopping completely isn’t appropriate unless there’s an immediate, unavoidable danger that requires it. The phrase “slow to discretion” isn’t a standard operating speed in this context, whereas bare steerageway is the defined practice for maintaining control while assessing risk.