All operators should navigate with extreme caution if visibility is restricted. The following applies to vessels not in sight of one another.
- Every vessel must proceed at a safe speed given the conditions of restricted visibility. A power-driven vessel must have its engines ready to manoeuvre immediately.
- Unless a risk of collision does not exist, an operator who hears the fog signal of another vessel ahead, is in a close-quarters situation with another vessel ahead, or detects the presence of another vessel by radar must reduce speed to the minimum at which the vessel can be kept on course. If necessary, the operator should reduce speed to idle speed.