It is a speed at which one can take proper n immediate action to avoid collision n b stopped at a distance appropriate in prevailing circumstances n condition
since th vessel is manouvering in restricted visibility we could take all way off and acess the situation...then take action acordingly..
any avoiding action must be taken in ample time,maintain your engine at safe speed,in circumstances of case admit as per the head on situation ,give one short blast alter the course to starboard side,that is safe pass on the port side of other vessel
inform to master regarding risk of collision, as rule no 19 E. says reduce her speed to minimum at which she can be kept on her course or stop and reverse propulsion because the area we area entering is 1.shallow water 2.Putting at us in risk of collision or we may aground.
Distress signal indicates that a mobile is in grave and imminent danger and requires immediate assistance