You hear the fog signal of another vessel forward of your beam. Risk of collision may exist. You MUST __________.

When you hear the fog signal of another vessel forward of your beam and recognize that there is a risk of collision, it is crucial to prioritize safety by taking all way off, if necessary. This action is fundamental to ensuring that your vessel is not making way into the path of the other vessel, which could lead to a dangerous situation.

Taking all way off means reducing your speed or potentially stopping your vessel to allow for better evaluation of the situation and to provide adequate time to react to the other vessel’s movements. This aligns with the International Regulations for Preventing Collisions at Sea (COLREGs), which emphasize the importance of reducing speed and taking precautionary measures when navigating in restricted visibility conditions, such as fog.

In this scenario, accelerating to clear the area could increase the risk of collision, as it may result in a sudden change in your vessel's position that the other vessel cannot anticipate. Maintaining current speed would be reckless, as it could lead to a collision if you're on a collision course. Issuing a warning signal may be necessary in certain circumstances, but it does not replace the need to take proactive measures to avoid an accident by controlling your vessel's movement.