Crossing Situation

Q. You are a power driven vessel, (model of power driven target ship shown 3 points on port bow crossing from port to starboard). What action will you take?
Ans. She is a power driven vessel seen on my port bow, seen crossing from my port to starboard. I am seeing her from her starboard side. This means her aspect is green. I will take bearings of a fixed feature of the target and monitor it. The steady bearings of target would mean that there is risk of collision. A small change in bearing does not rule out this risk.

This situation is governed by rule No. 15 of COLREG, ‘Crossing Situation, which applies to two power driven vessels in sight of one another. Since the target vessel in this crossing situation is to my port, I am the Stand-on Vessel‘. Target vessel is the Give Way’ vessel. As directed by the rule, I will keep my course and speed, monitor her at the same time, until she is passed and clear.

Q. Can you rule out the possibility of collision if there is appreciable bearing change?
Ans. Except, when there is appreciable bearing change, the risk of collision is deemed to exist. But such risk may sometimes exist, even when an appreciable bearing change is evident, particularly when approaching a very large vessel or a tow or when approaching a vessel at close range.

Q. Which part of a towing vessel will you monitor on bearing?
Ans. Normally, the give-way vessel should avoid crossing ahead of stand-on vessel which means her bearings will open out. In such a situation, bearing of the STEM of towing vessel must be taken. In situation where the towing vessel is crossing ahead of me, I will take the bearings of the STERN of her tow. If the bearing of STEM as well as STERN is taken then it is ensured that both clear on the same side.

Q. The target vessel is not taking appropriate action. (The models are brought closer on their original headings). What action?
Ans. As soon as it becomes apparent to me that the give-way vessel is not taking appropriate action, in accordance with these rules, I will sound at least five short and rapid blasts on ship’s whistle, if necessary, supplemented by at least five flashes and inform Master. As per rules, stand-on vessel may take action to avoid collision by her maneuver alone but if the circumstances of case admit not alter course to port for vessel on her port side. The maneuver is indicated by sounding appropriate signal.

Q. What is the most appropriate action?
Ans. When it becomes apparent to me that target vessel is not taking appropriate action; I will give one short blast on whistle to mean that I am altering my course to starboard. I will alter course by say 300 – 400 for a certain amount of time. When it is appropriate I will come back on the original course.

Q. What if she takes action or does not take action at all, subsequently you find yourself so close to her that collision cannot be avoided by her action alone?
Ans.  In this situation I shall take such action as will best aid to avoid collision. This means that any action viz; the increase of speed; decrease of speed; stopping her; reversing engines; or any appropriate alteration on even combination of any of the above action can be taken, so long as it helps avoiding collision. Alteration to port also can be done to avoid collision.

Q. Are you required to keep clear of towing vessel on your port side?
Ans. No, a towing vessel is to be treated as a power driven vessel, unless where she and her tow are severely restricted in their ability to deviate from the course they are following.

Q. Any special precaution for a towing vessel that is ‘give way’ vessel?
Ans. Yes, as per rule 2, Responsibility of COLREG, I have responsibility to observe precautions which may be required by the ordinary practice of seamen, or by the special circumstances of the case. In construing and complying with these Rules, I shall have due regards to the dangers involved in respect of towing vessel and her tow and the limitation of the towing vessel in the given circumstances. Even Rule 8 (a) states that any action to avoid collision shall be taken in accordance with the rules of the Part, that is ‘Steering and Sailing Rulesand shall, if the circumstances of the case admit, be positive, made in ample time and with due regard to the observance of good seamanship.

Q. How about taking a 3600 turn?
Ans. There are some dangers involved in taking a 3600 turn,

1. Duty officer including ARPA will lose orientation.

2. It may take well over 10 minutes for a large ship to complete a 3600 turn.

3. By the time a turn is completed, new ships may come within close range.

4. The turn normally, cannot be abandoned half way to keep clear of yet another vessel.

5. Due to tidal streams the turn may get elongated in a certain direction.

6. It cannot be tried in an area of dense traffic.

Q. Can you alter course to port if the target is restricted in her ability to maneuver?
Ans. Yes, as per rule 18, ‘Responsibilities’ between vessels I shall keep out of the way of a vessel restricted in her ability to maneuver. I can alter course to any side.

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2 responses to “Crossing Situation”

  1. Sir
    I am not able to understand the explanation regarding morning sights. Some notes that is circulating among students say that the morning sight be calculated by long by chron method and not intercept method. The reason mentioned for the above states that the rate of change of hour angle is small compared to that during the later part of the day.
    My doubt is that in both long by chron method and intercept method we are solving the same PZX triangle how come one method will be more accurate than the other. In solution of a triangle all the methods has to be equally accurate. If the change in hour angle varies w.r.t. time then the body shall move on the declination circle at different speed on different part of dec circle. But this is not the case as heavenly bodies are assumed to move at a constant speed on the dec circle for navigation purposes.
    Please explain this in your future videos.
    The above question was asked in my oral examination. I answered what my fellow candidates said and the same is written in the notes circulating among them but I am not able to digest the explanation given by my fellow candidates.
    Thanks and regards
    Ravi Shankar
    Mates candidate.

    1. Shashanka Chaudhari Avatar
      Shashanka Chaudhari

      Dear Ravi Shankar,
      Good that you raised this question which might be there in the minds of many. I have published the relevant article, a few days ago. I hope It answers your question. You may share the information with your colleagues, who are also confused with the concept. Please find below the link to the article:

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