Re: Collision Avoidance, Cones of Uncertainty, and Appropriate CPA
 

I suspect that you missed the fact that my previous post concluded with a quotation from:
"A Guide to the Collision Regulations" by A. N. COCKCROFT and J . N. F. LAMEIJER
(commonly known as "Cockcroft").

The principles stated are not mine, they are the exact words of the recognised authority on the subject. Specifically the authors' comments on Rule 9. There are about 10 pages of comments and quoted case law on the Rule which are well worth reading.

Re: Collision Avoidance, Cones of Uncertainty, and Appropriate CPA
 

StuM, what do you understand the word impede means? As to my quoted paragraph in post 120 you did not answer my question as to where the large vessel should go. Rule 9b reflects the change from 1972 where sail no longer has priority in restricted waters. I don't believe 13a overides 9b. unfortunate,you cannot create rules written in such a way as to allow for human stupidity so my original question was really a case of if one followed the rules would that suggest that the restricted vessel should have a free run up the waterway.I have consistently stated that every vessel must take action to avoid a collision but it seems to me that something I take for granted I must repeat on every post. I await with interest your response.

Re: Collision Avoidance, Cones of Uncertainty, and Appropriate CPA
 

I understand it to mean what Cockcroft says:
The following item of Guidance was approved in 1982 by the Maritime Safety Committee; ‘When a vessel is required not to impede the passage of another vessel, such a vessel shall so far as practicable navigate in such a way as to avoid the development of risk of collision. If, however, a situation has developed so as to involve risk of collision, the relevant Steering and Sailing Rules shall be complied with.’

The above Guidance is now superseded by the new Rule 8(f) which establishes clearIy that the requirements of ‘not to impede’ are complementary to other requirements of the Steering and Sailing Rule.

IOW, "not to impede" is applicable only prior to a risk of collision eventuating. Once the risk does eventuate, "not impede" becomes irrelevant and the other Rules come into play.

Re: Collision Avoidance, Cones of Uncertainty, and Appropriate CPA
 

See previous post. 9(b) did not change the situation so that sail no longer has priority in restricted waters.

I believe it does. This seems quite clear to me:

Notwithstanding anything contained in the Rules of Part B, Sections I and II, any vessel overtaking any other shall keep out of the way of the vessel being overtaken.

Re: Collision Avoidance, Cones of Uncertainty, and Appropriate CPA
 

I did answer it as best I could given that it is a hypothetical with limited factors described:
"the small vessel becomes stand one and the large vessel is required to take action - be it alter course, slow down, speed up or whatever."

The specific action to be taken by the large vessel will be dependent on the particular circumstances and prudent seamanship.

Re: Collision Avoidance, Cones of Uncertainty, and Appropriate CPA
 

OK, now I understand you.

And sure -- I don't think there's anything wrong starting off with new students by saying something like "vessels under sail have right of way over powered vessels underway", then going right on to explain that "but it's not 'right of way' at all, because unlike on the road, we don't have any 'rights', and here is what we are obligated to do . . ." etc. We have an experienced ASA instructor on here -- Snore -- and he does just that. I think it's not only OK, but actually essential, to discuss "right of way" and how it is different from standing on.

As to "improving on the wording of the c regs" -- I wouldn't dare. The more I study them, the more I respect the way they are written and how they work.

As to your river situation -- if it is in Europe, it's governed by CEVNI, not COLREGs. I don't know anything about CEVNI, and have never navigated on a European inland waterway, so I won't waste space here by writing about something I don't understand.

Re: Collision Avoidance, Cones of Uncertainty, and Appropriate CPA
 

So we're now arguing about the meaning of the word "lost"? :D This is getting better and better . . .

Well, I have to disagree. The word "lost" is absolutely correctly applied to situations where the condition is not absolute or permanent. Otherwise, the phrase "lost forever" would be a tautology. "I've lost my keys" doesn't necessarily mean "I've lost them forever, and will never find them again." Just like "I lost a winch handle overboard" doesn't mean that it is absolutely impossible to recover it -- it might correctly mean simply that it's not worthwhile to attempt to recover it, so it's lost to me.

Re: Collision Avoidance, Cones of Uncertainty, and Appropriate CPA
 

Stu is absolutely correct, and this is one of the rather fine points in the Rules. This was the point about which I corresponded with Cockcroft himself a few years ago.

The short answer is this: Rule 9 does NOT trump Rule 13. These two Rules apply at DIFFERENT TIMES.

As Stu correctly said (and he is one of the few people I have run into who understand this :thumb:), in order to fulfill the obligations of Rule 9, you must maneuver early enough that the risk of collision never arises in the first place.

If for any reason you fail to prevent a risk of collision from arising, then Rule 13 is fully applicable. Your Rule 9 obligation to "not impede", however, continues.

What this means is that you could be obligated to stand-on AND not impede at the very same time. This is what bothered me so much that I found Cockcroft and wrote to him about it. I am grateful to Lodesman who was the one who pointed this out to me, years ago, in an argument on CF, and proved me wrong when I insisted that this could not possibly be so.

It really is so. And it is not as paradoxical as it first seems, when you correctly understanding what standing-on really means.

Re: Collision Avoidance, Cones of Uncertainty, and Appropriate CPA
 

Can there be any controversy on this point? I think everyone agrees with you, completely. It's kind of the one fundamental principle of collision avoidance, actually.

Re: Collision Avoidance, Cones of Uncertainty, and Appropriate CPA
 

I think Stu has answered this already.

I was referring to U.S. Inland Rule 9(a)(ii), which applies ONLY to a vessel proceeding down a river with a following current. This is the ONLY case where right of way exists -- and the U.S. Coast Guard specifically says this on their official site. They take pains to distinguish the condition of having explicit right of way under Inland Rule 9(a)(ii) from the case where you are obligated to stand on under Rule 17, and well they should, because what you are allowed to do and what you are required to do are completely different in those two different cases.

If a vessel is supposed to "not impede" you under Rules 9 or 10, then this is even further away from anything like "right of way". It is yet again something different. You must give way to a vessel which is obligated to "not impede" you, in case a risk of collision arises -- Rule 13 explicitly applies notwithstanding anything in Rules 9 or 10.

So what that means is that if you are a fully loaded supertanker following a channel into Rotterdam, and a little sailboat under sail crosses the channel and gets in your way, you are obligated to give way to the sailboat as best you can, and the little sailboat is obligated to stand on so that you can effectively do that, up until the point he has a reasonable doubt that the supertanker is maneuvering effectively.

Depending on the distances involved, the amount of time the little sailboat must stand on prior to this doubt arising may approach 0 -- that is because any such encounter is likely to be an "in extremis" situation where the maneuver of the give way vessel is already not going to be enough in any case. So of course in practice, the little sailboat should be doing its best to get back out of the channel as fast as possible. But legally -- the supertanker is obligated to give way, and this obligations continues into the the "in extremis" phase, and the supertanker must do everything it can to give way. If the little sailboat has sailed right under its bows, then there might be nothing whatsoever the supertanker can do, but that's where "everyone is at all times obligated to do what is necessary to prevent a collision" comes in -- Rule 2, also the obligations of the stand-on vessel under Rule 17(b).

Re: Collision Avoidance, Cones of Uncertainty, and Appropriate CPA
 

If you re-read Cockcroft, you will find the above directive was out of the MSC's 1982 Guidance, which was superseded by Rule 8(f). The rule spells out that a vessel required to not impede (VRTNI) aware of the approach of a vessel that is not to be impeded (VNTBI) should take early action to allow the safe passage of the VNTBI, whether it is in sight or not.

"Safe passage" is not described sufficiently by the rules or Cockcroft, but as the "not impede" rule is only used in situations where vessels are constrained by the available draught and width of channel, then it can reasonably be surmised that so long as there is safe, navigable water through which the VNTBI can manoeuvre, it is not impeded.

If the VRTNI is blocking the deep-water channel, and the VNTBI cannot manoeuvre around it, then the VNTBI is impeded. The VRTNI would have failed in its requirements, but at this point would be required to do whatever is required to allow the VNTBI safe passage; while the VNTBI would be required to avoid the collision by whatever means necessary, with no requirement to endanger herself navigationally.

Re: Collision Avoidance, Cones of Uncertainty, and Appropriate CPA
 

For the sake of clarity, you are not disagreeing with, but rather elucidating Stu's comment, right?

Some commentators believe that the VNTBI is impeded if it has to maneuver at all -- not just if it is put into a position where it cannot maneuver around. I don't have an opinion on this; I'm just stating for the record that such a position exists. Your thoughts on the matter would be very interesting for many of us, I think.

Re: Collision Avoidance, Cones of Uncertainty, and Appropriate CPA
 

I'm not disagreeing with Stu per se; I don't believe he has a complete understanding of the rule, given his citing of an obsolete Guidance. Stu can be forgiven, because this is a poorly-understood concept, even amongst professional mariners. As you suggest, many equate being impeded, with any requirement to manoeuvre, and that IMO is patently wrong. It is certainly inconsistent with the wording of the rules, and the guidance (as little as there is) as written by Cockcroft.

Take the example that a tanker is proceeding along a traffic lane at 20 kts, to the stbd side in the lane. He approaches a freighter making 12 kts, also to the stbd side in the lane. Well the tanker will simply alter a couple degrees to port and pass the freighter, staying safely within the lane and leaving the freighter a safe distance to stbd - he won't even need to change speed.
Now imagine the same scenario, but in place of the freighter, we put a PDV under 20 metres. The commentators you talk of, would now consider the tanker to be impeded; you have to admit, that is preposterous.

Re: Collision Avoidance, Cones of Uncertainty, and Appropriate CPA
 

I have always thought it to be fairly logical that if while sailing across a TSS, if I put a ship in a lane in a position where it had to maneuver to avoid me, that I had violated my obligation to "not impede".

Your point is well argued, though. Is there any reading on this you can recommend? I have to write something on this and I have to be sure that I have read everything on the subject which is important. Or maybe you'd like to write this chapter?

Re: Collision Avoidance, Cones of Uncertainty, and Appropriate CPA
 

DH/Lodesman my view is that you appear to have 2 scenarios rolled into one.If your sailing vessel is proceeding up the channel then in my view the tanker is an overtaking vessel and is thus required to keep clear as per rule 13. If however a vessel which according to rule 3a means every type of water craft crosses a narrow channel in such a way as to cause your tanker to alter course then is that craft not impeding the tanker rule 9d particularly if it crosses from starboard side and then suddenly becomes the stand on vessel. At what point does this change occur? My understanding of the word impede is based on US dictionary = bar or hinder the progress of, obstruct or delay. Could you please advise when you are referring to USCG regs for inland waters and rivers as they are not all the same as International c regs, Does Canada use the USCG regs or do they have their own rules?