COLREGS Question

Of course I’m gonna blame Pascal and Cappy J. LOL.


It seems there was a little confusion on another thread. Capn J was of the opinion that you can be over taking and crossing, and Pascal however succinctly rebutted it by stating, "if you are 22.5° or less abaft the beam, you are crossing". COLREGS is very clear: There are only three possibilities for vessels in sight of each other; meeting, crossing, & over taking. So I'm in the "Pascal" camp. [Sorry Cappy]

So here’s the hypothetical situation for you to ponder:
You on a vessel heading 000° true and detect on radar, a vessel 25 miles away bearing 120° true (30° abaft the beam. He is not visible. You also notice he has left bearing drift and the range is closing and its speed is 3 knots faster than yours. Pretty soon the radar indicates a very tight CPA ( closest point of approach). An hour later, you see the ship on the horizon, and you observe him on the radar at 100° true (10° abaft the beam).

It now appears that the CPA will be very tight, and risk of collision is high.

Here are the questions:
1) What situation exists; Overtaking or crossing?
2) Which vessel is the giveaway vessel; your vessel or the other?

Enjoy

Nope. Deflecting is not a correct answer, my friend. And besides, the question isn't "what would you do". The questions were: What situation exists, and who is the stand-on vessel

Although your high school metaphor is good, your vessel would never make it to your destination in a timely fashion by making course changes whenever you detect a ship at 25 nautical miles that indicates a tight CPA at 25NM. Also, if you are on a commercial ship, the captain would be up your butt for sailing delays, and excess fuel consumption; and if you are the captain, the company would soon find your permanent relief. In a private vessel, perhaps it wouldn't matter.

When you said, ". . started collision avoidance steps an hour ago", the range to the vessel on the horizon, which is a function of your height-of-eye and the other vessels size, is measured by several miles (true, I didn't mentioned that visibility was unrestricted by weather). So that hour between detection on radar, and detection visibly on the horizon gives plenty of time to allow the situation to mature, for the data to become more reliable, and to adequately assess the risk of collision. CPA's calculated at 25NM are never as accurate as 10-12NM.

Cheers!

Crap. Can't fool you!! Now I owe you two grogs!!

But wait, he was detected 30 deg abaft the beam. . . why isn't he "overtaking"?
(this question was a conundrum for me in my younger 3m days!! Fortunately, "I matured".LOL)

Cap'n Fred, you are correct - and incorrect, sorry. . . But you come by it honestly!! And this was the conundrum I had as a young Third Mate.
You are correct, in that IAW (in accordance with) Rule 13 (d), "Any subsequent alteration of the bearing between the two vessels shall not make the overtaking vessel a crossing vessel within the meaning of these Rules or relieve her of the duty of keeping clear of the overtaken vessel until she is finally past and clear."

But you are, unfortunately, incorrect in the full assessment of the situation, and here is why (It also was my, "Ohhhh. Nooo Shhh!T" moment!!)

IAW COLREGS Section 2; Rules 11 through 18 apply, to the conduct of vessels in sight of one another.

In the example offered, the vessel was detected on radar at 25 NM, but was not visible until 1 hour later. When the vessel was visible, it was forward of the 22.5 degree metric for crossing/overtaking. As a result of the "visual detection", the correct assessment is: CROSSING, and RULE 15 is applicable for establishing which vessel is the "give way" and "stand on" vessel. I recently discovered an article from Professional Mariner magazine, written in 2013 - well after my "Master" days. It's attached for further education.

When I was master of deep sea vessels, I routinely used this scenario to educate the bridge mates. It almost always trips up the mates.

One aspect that should be explored, is "proximity" and "what is a satisfactory CPA". We all know what our individual "pucker factor" is, but what "should" the pucker factor be? Of course, we all know it depends on what water's we are on, and what the traffic density is.

I'll use deep-sea vessels as an example. In the open ocean, the unwritten convention is 1.5-2.0 minimum CPA. It will vary somewhat-I've seen 1.0NM CPA on the stern with no concern, and if the USN is involved, they will always seem to ask for 5NM.

In confined waters, the CPA may be as low as .5NM, and it does acquire some intestinal-fortitude. And in narrow channels, with a pilot on board, I've seen 50-60 ft between large ships. It takes guts & a firm hand on the helm.

In the deep sea world, with minimum traffic, we don't worry too much about 25NM contacts; we pay attention to the ones that are at 10-12NM through the 4-5NM range (often referred to as the "assessment or determination area". We observe what is going on with that ship, assess the situation, and wait for the 4 to 5nm point (often referred to as the "execute" range), at which the give-way vessel usually puts the rudder over. VHF communication usually does not take place until the other ship isn't maneuvering (so as to avoid a "radio assisted" collision). That's when the call-up is made and establish the give-way vessel's intention. If there is ANY confusion, there is time at this 4-5 NM range for the stand-on vessel to take action if the give-way vessel does not. In reality, it's quite easy, and very little pucker. It's when the other guy doesn't answer when things get interesting.

It also gets very interesting when the stand-on vessel changes course, especially when they turn to port!! One can see the conflict, when involved in a crossing situation with a vessel on your starboard side, if that ship suddenly turned to port - especially when you've just put your rudder over to starboard!! (Yes. I've seen it happen way too often, and it usually resulted in a frantic and energetic VHF call on 16 with a lot of colorful language, f-bombs, disparaging remarks about ancestry and education.)

In the English Channel or Malacca Straits you will not get a 2NM CPA. And you don't worry about contacts at 25NM, because you are paying attention to the ships within 4NM. In those places, the good news is that you don't have to worry too much about "meeting", it's all overtaking, or crossing. Ahh, fond memories of 4 box ships, all .2NM apart steaming at 15, 17, & 18kts, being overtaken by a 25kt ship at .4NM. HOLD ON BABY!! And remember, the big ships can't vary their speed really. It's not like the USN which has a manned ER.

In the yachting world, when traveling from Port Canaveral to FLL in the LANT at a leisurely 10kts, why does some nut going 30KTs think a CPA of 50-100 yards is ok!! Proximity (in relation to speed) is paramount. It seems to me, that 1/4 mile CPA in the ocean is prudent and appropriate at such speeds - no risk of collision & no wake issues. In the ICW, 100 ft CPA is great, unless it's that 30kt A-hole again.

In summary, I'd opine that we all should reacquaint ourselves with COLREGS, maintain our situational awareness, and find the fine line between reckless and cautious. I've seen acceptable risk-of-collision situations deteriorate because the vessel was too cautious, i.e. very small course changes, or speed changes. Know the rules & Follow the rules; they are your friend.

Please read post #1

Hey Cappy R!! The details were in post #1; but the explanation was in post #9.
As a young hard-charging 3rd Mate back in 1993, I was pretty sure I had the correct answer when first presented with the hypothetical question contained in post #1. "Of course we are 'stand-on', we are being overtaken", I thought/said. But some Yoda guy, said something to the effect of: "Ah yes young jedi, but he's out of VISUAL range". I was suitably humbled!!

It is post 50 from the tin-can page. The thread was closed before folks could respond, so I opened a new one.