Collision Avoidance, Cones of Uncertainty, and Appropriate CPA

[Exile]

I still don't understand why it would ever be advantageous for a sailing vessel properly standing on to purposely wait for a late maneuver if the give way vessel is not giving way within the generally accepted parameters set forth by the Rules, and is not responsive or understandable on the radio. Seems to me you'd want to have this sorted out at least a couple of miles out so you have room to spare if need be, and then calmly make your decisive & obvious maneuver. I understand it doesn't always work out this way, but if you understand the Rules why would you want to wait?

This is assuming a two-boat crossing scenario in open waters. May call for later maneuvering & closer crossings in busy shipping lanes where add'l boats are in play, or in the midst of fast-moving ferry routes, etc. Each situation, including sea-state & weather, has the potential to present many different variables.

[ramblinrod]

Originally Posted by Exile

I still don't understand why it would ever be advantageous for a sailing vessel properly standing on to purposely wait for a late maneuver if the give way vessel is not giving way within the generally accepted parameters set forth by the Rules, and is not responsive or understandable on the radio. Seems to me you'd want to have this sorted out at least a couple of miles out so you have room to spare if need be, and then calmly make your decisive & obvious maneuver. I understand it doesn't always work out this way, but if you understand the Rules why would you want to wait?

This is assuming a two-boat crossing scenario in open waters. May call for later maneuvering & closer crossings in busy shipping lanes where add'l boats are in play, or in the midst of fast-moving ferry routes, etc. Each situation, including sea-state & weather, has the potential to present many different variables.

Asked and answered mostly. The rules do not state when one must or should deviate from stand on. By the rules, one may do it when it is apparent the give way vessel is not, one must when the give way vessel can't. Where these distances are, are dependant on the vessel, the conditions, and the pucker factor of both vessel operators.

[Exile]

Originally Posted by ramblinrod

Asked and answered mostly. The rules do not state when one must or should deviate from stand on. By the rules, one may do it when it is apparent the give way vessel is not, one must when the give way vessel can't. Where these distances are, are dependant on the vessel, the conditions, and the pucker factor of both vessel operators.

Absent some sort of negligence or confusion on the part of one or both operators, why would 'pucker factor' even enter it? I understand your point about the (deliberate & necessary) lack of specificity in the Rules, but every statute or set of regulations contains an express or implied requirement of reasonableness, which in the case of the Colregs amounts to an objective standard of what a consensus of seasoned, experienced mariners would do. This is reflected by implication throughout the Rules themselves, applied in published case law which is then used as legal precedent to adjudicate fault, explained & supported by published commentary from acknowledged experts such as 'Cockcroft', and confirmed by many commercial ship mariners as we've read. So it seems that, even absent specific distances laid down in the Rules, there is a well-established & reasonable course of conduct that all mariners are expected to follow, and most professional ones in fact do. It just doesn't seem to follow that the Rules would therefore condone some of the close crossing scenarios you've presented if, as is usually the case, they can easily be avoided.

I'm not interested in resurrecting the same old arguments here. Indeed, I don't even understand why the topic is so controversial. But to me, and please correct me if this is not what you intended to say, 'pucker factor' implies the old game of 'chicken' which is obviously not what the Rules contemplate.

Or is your point simply that, since the Colregs are designed to avoid collisions, and since you've avoided collision by executing one of the close maneuvers you've cited, you have therefore not violated the Colregs? First, that's apparently not true since violations have been and are prosecuted in the absence of actual collisions. And specific distances, while not expressly defined in the Rules, must fall within what is generally accepted as reasonable. Secondly, rules, regs & statutes are violated all the time without the harm they are intended to prevent coming to pass. Just because one may have escaped such harm doesn't justify actions which greatly increase its risk of occurring. That's the whole point!

But even leaving the 'legalities' aside, why as a practical matter would you deliberately wait so long -- assuming you have the option that is -- to exercise your obligation to maneuver when confronted with a give way vessel who is not properly giving way? If I thought you simply didn't understand the Rules or lacked experience as a mariner, my questions could be construed as argumentative. But since you are both experienced and knowledgeable, my questioning is to try and eliminate the confusion I have in my own mind over your approach.

[TJ D]

Originally Posted by Exile

Absent some sort of negligence or confusion on the part of one or both operators, why would 'pucker factor' even enter it? I understand your point about the (deliberate & necessary) lack of specificity in the Rules, but every statute or set of regulations contains an express or implied requirement of reasonableness, which in the case of the Colregs amounts to an objective standard of what a consensus of seasoned, experienced mariners would do. This is reflected by implication throughout the Rules themselves, applied in published case law which is then used as legal precedent to adjudicate fault, explained & supported by published commentary from acknowledged experts such as 'Cockcroft', and confirmed by many commercial ship mariners as we've read. So it seems that, even absent specific distances laid down in the Rules, there is a well-established & reasonable course of conduct that all mariners are expected to follow, and most professional ones in fact do. It just doesn't seem to follow that the Rules would therefore condone some of the close crossing scenarios you've presented if, as is usually the case, they can easily be avoided.

I'm not interested in resurrecting the same old arguments here. Indeed, I don't even understand why the topic is so controversial. But to me, and please correct me if this is not what you intended to say, 'pucker factor' implies the old game of 'chicken' which is obviously not what the Rules contemplate.

Or is your point simply that, since the Colregs are designed to avoid collisions, and since you've avoided collision by executing one of the close maneuvers you've cited, you have therefore not violated the Colregs? First, that's apparently not true since violations have been and are prosecuted in the absence of actual collisions. And specific distances, while not expressly defined in the Rules, must fall within what is generally accepted as reasonable. Secondly, rules, regs & statutes are violated all the time without the harm they are intended to prevent coming to pass. Just because one may have escaped such harm doesn't justify actions which greatly increase its risk of occurring. That's the whole point!

But even leaving the 'legalities' aside, why as a practical matter would you deliberately wait so long -- assuming you have the option that is -- to exercise your obligation to maneuver when confronted with a give way vessel who is not properly giving way? If I thought you simply didn't understand the Rules or lacked experience as a mariner, my questions could be construed as argumentative. But since you are both experienced and knowledgeable, my questioning is to try and eliminate the confusion I have in my own mind over your approach.

This is a fabulously articulate post. I haven't waded into this one too much, but this is exactly my thinking on this. Well done.

[Dockhead]

Originally Posted by ramblinrod

Asked and answered mostly. The rules do not state when one must or should deviate from stand on. By the rules, one may do it when it is apparent the give way vessel is not, one must when the give way vessel can't. Where these distances are, are dependant on the vessel, the conditions, and the pucker factor of both vessel operators.

Yes, you stated the rules exactly right.

The only thing is that the risks increase, and your options decrease, as you get closer. This is not subjective -- this is not a question of "pucker factor". At some point, the risks become unreasonable. At some greater distance, you have time to get out of the way with an easy maneuver and you will still have time left to correct if the other vessel does something unexpected, or it turns out you misjudged something in the crossing. At some lesser distance, those options disappear, and getting out of the way requires a hard and perhaps gear-damaging maneuver, and if you misjudged even a little, or if the other vessel maneuvers unexpectedly, then you can no longer get out of the way. Can we agree on that?

So the question boils down to -- do you know where that point is? It is different in every crossing of course, as you correctly stated. The idea which started this thread is that you cannot have perfect knowledge about where he will be or where you will be when you reach CPA (or collide), and this needs to be taken into account when you decide when to maneuver.

[Dockhead]

Originally Posted by TJ D

This is a fabulously articulate post. I haven't waded into this one too much, but this is exactly my thinking on this. Well done.

I agree, and this is as usual from Exile.

[carstenb]

Originally Posted by Exile

Absent some sort of negligence or confusion on the part of one or both operators, why would 'pucker factor' even enter it? I understand your point about the (deliberate & necessary) lack of specificity in the Rules, but every statute or set of regulations contains an express or implied requirement of reasonableness, which in the case of the Colregs amounts to an objective standard of what a consensus of seasoned, experienced mariners would do. This is reflected by implication throughout the Rules themselves, applied in published case law which is then used as legal precedent to adjudicate fault, explained & supported by published commentary from acknowledged experts such as 'Cockcroft', and confirmed by many commercial ship mariners as we've read. So it seems that, even absent specific distances laid down in the Rules, there is a well-established & reasonable course of conduct that all mariners are expected to follow, and most professional ones in fact do. It just doesn't seem to follow that the Rules would therefore condone some of the close crossing scenarios you've presented if, as is usually the case, they can easily be avoided.

I'm not interested in resurrecting the same old arguments here. Indeed, I don't even understand why the topic is so controversial. But to me, and please correct me if this is not what you intended to say, 'pucker factor' implies the old game of 'chicken' which is obviously not what the Rules contemplate.

Or is your point simply that, since the Colregs are designed to avoid collisions, and since you've avoided collision by executing one of the close maneuvers you've cited, you have therefore not violated the Colregs? First, that's apparently not true since violations have been and are prosecuted in the absence of actual collisions. And specific distances, while not expressly defined in the Rules, must fall within what is generally accepted as reasonable. Secondly, rules, regs & statutes are violated all the time without the harm they are intended to prevent coming to pass. Just because one may have escaped such harm doesn't justify actions which greatly increase its risk of occurring. That's the whole point!

But even leaving the 'legalities' aside, why as a practical matter would you deliberately wait so long -- assuming you have the option that is -- to exercise your obligation to maneuver when confronted with a give way vessel who is not properly giving way? If I thought you simply didn't understand the Rules or lacked experience as a mariner, my questions could be construed as argumentative. But since you are both experienced and knowledgeable, my questioning is to try and eliminate the confusion I have in my own mind over your approach.

BRAVO! This just about sums up my stand, extremely well-written

[El Pinguino]

Originally Posted by Exile

But even leaving the 'legalities' aside, why as a practical matter would you deliberately wait so long -- assuming you have the option that is -- to exercise your obligation to maneuver when confronted with a give way vessel who is not properly giving way? If I thought you simply didn't understand the Rules or lacked experience as a mariner, my questions could be construed as argumentative. But since you are both experienced and knowledgeable, my questioning is to try and eliminate the confusion I have in my own mind over your approach.

The bearing started opening at 2 miles..... maybe he had made a slight alteration... maybe it was just that at greater range the change was not discernable..... maybe he was happy with that CPA... I doubt he was plotting it... would have just been eyeball.

I though 100 metres was 'on the edge' and would have been happier if he had made his intentions - if any - more obvious.

Which leads to the question...what is a safe distance ahead if the vessel involved is 10 metres long? 50 metres? 100 metres? 200 metres? and what is a safe distance ahead if the ship you are crossing ahead of is doing 5 knots, 10 knots, 20 knots?

An infinite combination.... to which can then be added an infinite number of comfort levels......

The oft quoted Cockcroft was at sea in far simpler times... I am unsure of when the 1st edition of 'Cockcroft' was published but he edited the 1979 edition of 'Nicholls's Seamanship and Nautical Knowledge' which would suggest he was ashore with his 'extra masters' by about 1970. Pre 1970 a ship longer than 500 or so feet was a rarity as was a ship faster than about 16 knots.... passenger liners , the large tankers that were starting to appear, ferrys, and US flag cargo liners being the exceptions.

[ramblinrod]

Originally Posted by Exile

Absent some sort of negligence or confusion on the part of one or both operators, why would 'pucker factor' even enter it? .

Asked and answered.

Your post is very eloquent, but extremely flawed by idealism (either intentionally or unintentionally) in my opinion.

I tend to be a realist.

In any circumstance where one is required to do something at an unspecified "safe" distance, those who have personal need for greater "safety" will respond sooner and more conservatively than those who have personal need for lesser "safety".

This may be referred to as "Pucker Factor".

If the term "Pucker Factor" offends anyone, please use the synonym, "Personal opinion of what is safe."

On the race course, if I have to give way in a crossing, I will wait to the very last moment to ensure that conditions don't change, and that I really have to duck, and then will miss by the closest margin possible as to not give up any more ground than absolutely necessary.

One with less tolerance, or confidence in their skills, may respond sooner, and by a wider margin.

In other words, some have a greater "Pucker Factor" than others.

That is the race course.

Of course, nobody in their right mind would cut so close in a crossing between a large ship and a sailboat, intentionally, and obviously I am not suggesting this for one second, so I am quite troubled by the "chicken" inference in this post.

Never-the-less what can be considered a "safe" distance, will vary depending on the conditions (as Cockcroft clearly states) and the skill, and the "Pucker Factor" of the person responsible for the call.

In every case, for every maneuver, "Pucker Factor" comes in to play.

1. Under what wind conditions will we leave the dock?

2. At what wind level do we reef? 3. How far before shallows do we tack?

3. And so on and so on and so on...every action where safety could possibly be involved.

To suggest that every move one makes aboard has to be in accordance with "case history" where the rules do not specify values, is ridiculous.

If that was the case, I would not wish to sail, and I doubt many others would either. The reason I hear most declare they get enjoyment from sailing is "freedom", not "adherence to rules and case history".

Speaking only for myself, I can't tolerate that level of "Pucker Factor". It wouldn't be fun anymore. Others may be wound so tight they cannot be happy until they can suck themselves inside out. That is OK for them, just don't try to convince me that I should be like that. I shouldn't. It wouldn't work. Not at all.

But to me, and please correct me if this is not what you intended to say, 'pucker factor' implies the old game of 'chicken' which is obviously not what the Rules contemplate

.

Correction: No, the inference was not intended and it is not the same thing, not at all. The only similarity is that there are two vehicles involved. That inference is offensive.

Or is your point simply that, since the Colregs are designed to avoid collisions, and since you've avoided collision by executing one of the close maneuvers you've cited, you have therefore not violated the Colregs?

Yes and No. If in my opinion, I met the requirements of Colregs in a reasonable and timely fashion, and avoided a collision, I have met my obligations under Colregs. One can argue until they are blue in the face otherwise. That is what lawyers are paid handsomely to do. That is what they thrive on. And there is absolutely nothing saying that the resulting justice is always just.

That is not what I am saying. What I am saying is "safe distance" is not a specific value, and what value represents "safe distance", may be different for different people, and under different circumstances.

But even leaving the 'legalities' aside, why as a practical matter would you deliberately wait so long -- assuming you have the option that is -- to exercise your obligation to maneuver when confronted with a give way vessel who is not properly giving way?

Asked and answered. The main reason, a desire not to act prematurely so as to interfere with a give way vessel's plans. Secondly, my level of "Pucker Factor" does not necessitate what I would consider a "premature" action over someone who has greater "Pucker Factor".

If I thought you simply didn't understand the Rules or lacked experience as a mariner, my questions could be construed as argumentative. But since you are both experienced and knowledgeable, my questioning is to try and eliminate the confusion I have in my own mind over your approach.

Actually, the tone and thrust of the message was argumentative, in contrast to this last sentence.

The questions have already been asked and answered many times. The analogies used are (or should be) knowingly flawed. The presumptions of the reasons for my position are (or should be) knowingly flawed.

However, based on you many prior posts in this thread that I did believe were very valuable and sincere, I do sincerely hope that this response helps to clarify my position on this discussion.

[evm1024]

If common sense is not enough I'll appeal to authority (yes I know). Consulting wikipedia:

Pucker factor is a military slang phrase used to describe the level of stress and/or adrenaline response in a dangerous or crisis situation. The term refers to the tightening of the buttocks caused by extreme fear. If it is inadequate, the person making decisions may make them "like a robot" without considering ethics or the long-term consequences of his actions; conversely, if it is excessive, then the person "puckers"--panics and becomes unable to think clearly and effectively.[1]

Common sense and common usage tells us that anytime there is "pucker factor" involved then there is "a dangerous or crisis situation".

It appears to me that the whole point of collision avoidance is to cross so as to ensure that there is no "dangerous or crisis situation". And further that anytime you have allowed a pucker factor to come into play by your actions or inaction then you have violated COLREGS.

Aggressive, arrogant, argumentative, type A persons might consider the pucker factor as a valid input for judging crossing situations. But the prudent skipper will not.

Of course Ron might just be choosing his words imprecisely and use pucker factor when he really means "deciding how bold I want to be when faced with a 400' foot monster and the rule of tonnage".

Lastly I thought the discussion was in open water not round the buoys.

I pass large ships within 100' all the time on the Columbia River. They are in the channel and their options are known.

I do recall using an escape bearing in the Straights of Juan de Fuca when a ships intentions were not clear to me and a collision situation developed. The point being that in open water ships appear huge at 1000' when you (at least I) do not know what they are intending.

[El Pinguino]

Originally Posted by evm1024

If common sense is not enough I'll appeal to authority (yes I know). Consulting wikipedia:

Pucker factor is a military slang phrase used to describe the level of stress and/or adrenaline response in a dangerous or crisis situation. The term refers to the tightening of the buttocks caused by extreme fear. If it is inadequate, the person making decisions may make them "like a robot" without considering ethics or the long-term consequences of his actions; conversely, if it is excessive, then the person "puckers"--panics and becomes unable to think clearly and effectively.[1]......

That is the US military usage of the expression.... which is quite different to the mercantile usage.

[Exile]

Originally Posted by El Pinguino

The bearing started opening at 2 miles..... maybe he had made a slight alteration... maybe it was just that at greater range the change was not discernable..... maybe he was happy with that CPA... I doubt he was plotting it... would have just been eyeball.

Sure, makes some sense. Provided there's an escape plan I suppose. And maybe one of those situations we've all found ourselves in when there's been a degree of confusion, miscommunication, etc. But then that's also an argument for maneuvering even earlier (if possible).

But what I gather is your larger point in all this -- that all the book study & analysis on dry land doesn't always translate well on the water -- is very well taken. For those of us without the benefit of your experience but who want to become more proficient, we often "go to school" first & then try and apply what we've learned out on the water. That's why your perspective & those like the "Wafinator" are so valuable.

I though 100 metres was 'on the edge' and would have been happier if he had made his intentions - if any - more obvious.

Not sure if you're referencing Rod's examples or the one you cited above about being hard on the wind on a starboard tack, with an oncoming big ship lying to your starboard. (Did I get the facts right?). As I recall, your dilemma was whether to ease sheets & fall off to port (maybe dicey as the other ship might naturally turn to starboard), or continue to stand on relying on the other ship to leave enough room for safe passing. Not for me to second-guess, but I may have just opted to tack and done so quite early, and then sailed (off course) on port tack for the relatively short amount of time it would take to get clear. That way you're in control. But of course if circumstances prevented such early action then you may be stuck with the limited options you described.

Which leads to the question...what is a safe distance ahead if the vessel involved is 10 metres long? 50 metres? 100 metres? 200 metres? and what is a safe distance ahead if the ship you are crossing ahead of is doing 5 knots, 10 knots, 20 knots?

An infinite combination.... to which can then be added an infinite number of comfort levels......

The oft quoted Cockcroft was at sea in far simpler times... I am unsure of when the 1st edition of 'Cockcroft' was published but he edited the 1979 edition of 'Nicholls's Seamanship and Nautical Knowledge' which would suggest he was ashore with his 'extra masters' by about 1970. Pre 1970 a ship longer than 500 or so feet was a rarity as was a ship faster than about 16 knots.... passenger liners , the large tankers that were starting to appear, ferrys, and US flag cargo liners being the exceptions.

Again, I'm coming at this with more book knowledge than experience (at least relative to yours), but these add'l factors of commercial vessel speed & size which have arisen in the past 40-50 years don't seem -- in my mind anyway -- to change the basic application of the Rules. If anything, it may necessitate earlier & more prudent action on our parts, but still well within the ranges that Cockcroft suggests and big ship caps seem to agree are safe to operate under. If unsure what's coming at you, I suppose you would want to assume higher speed & less maneuverability in planning your own maneuver (if necessary). In other words, if your late maneuver creates a close call with a fast, highly maneuverable ship, then it's theoretically also too close with a slow speed, slow maneuvering ship. And in some scenarios, of course, maybe the other way around! As for size, I'm not sure what that has to do with it since we're talking about sufficient margins that should keep us well clear of any sized ship.

What am I missing?

[evm1024]

Originally Posted by El Pinguino

That is the US military usage of the expression.... which is quite different to the mercantile usage.

Of course.

But in common usage it is the same, and Ron is not speaking as a professional mariner....

Pucker factor is a measure of how dangerous, risky, scary a situation is.

In open waters on a perfect blue sky day you detect a ship 10 miles out with a CPA of 0 - do you make minor course corrections and pass 180' to their stern? Why would you?

In open waters on a clear moonless night you detect a ship 10 miles out with a CPA of 0 - do you make minor course corrections and pass 180' to their stern? No way in hell!

I am not risk adverse and in open waters I don't want to be within 180' of any ship. It does not matter if I could do it or if I have brass balls and 0 pucker factor.

[ramblinrod]

Originally Posted by evm1024

Of course.

But in common usage it is the same, and Ron is not speaking as a professional mariner......

First of all, it is Rod.

Pucker factor is a measure of how dangerous, risky, scary a situation is

That is a reasonable definition. In one persons opinion, a given scenario may be considered much more dangerous, risky, or scary, than in another persons.

Hence, one person may have a greater Pucker Factor than another, under identical circumstances.

In open waters on a perfect blue sky day you detect a ship 10 miles out with a CPA of 0 - do you make minor course corrections and pass 180' to their stern? Why would you?

Nobody would. But under those conditions, it is reasonable for the sailboat to suspect the ship has seen them, and has planned a solution.

Under ideal conditions, the sailboat may stand on longer, waiting to see what that solution is, before determining the other vessel is not reacting to the situation appropriately, and they need to take action themselves.

What that specific distance is, is dependant on the conditions, any standing orders (not typically applicable to a rec sailboat) and the skipper's pucker factor.

Again, someone who is comfortable may wait longer than someone who is not comfortable. That simple.

What is that distance? You decide for you; I'll decide for me, others will decide for themselves.

If one can't tolerate that others may have a different comfort factor in a crossing situation, they should stay off the water, because they certainly do, even at the professional mariner level.

[ramblinrod]

Originally Posted by Dockhead

Yes, you stated the rules exactly right..

Of course.

Thank You for acknowledging that.

The only thing is that the risks increase, and your options decrease, as you get closer.

Agreed wholeheartedly and without question, no argument whatsoever, here or anywhere in this thread.

This is not subjective -- this is not a question of "pucker factor".

This is yet another in an almost infinite string of strawman arguments.

It is akin to me stating, "I don't give a damn what you think Dockhead, I believe the world is round, and nothing you can say will change my mind on that."

Regardless what the actual risk is, one's perception of the degree, and tolerance of it, may be completely different than another's. Pretty much completely subjective.

At some point, the risks become unreasonable.

Thank You! Exactly! Finally!

At "SOME" point. That point is not a specific value, and it is most certainly "SUBJECTIVE" based on the conditions and "Pucker Factor" of the individuals involved.

What is the "safe distance" for one to pull the ripcord of their parachute?

a) For some, there is no safe distance, they may feel that going up in a small plane is unsafe.

b) For others, they may feel they need to be tethered, and have their chute automatically deploy.

c) For others, 3000 ft, may be the amount of time they feel they need to be comfortable seeing the primary deploy, and allowing time to blow it and pull the emergency.

d) For others, 1000 ft may be plenty.

And the real point I want to make; every single one, may be absolutely correct, based on their risk tolerance and pucker factor.

How long should the sailboat stand on, before evasive maneuvers? Can't say, without know the "Pucker Factor".

a) For some, it will be "sailboats are not safe", I would never go out on one.

b) For others, I wish to maintain a 2 nm CPA under all circumstances.

c) For others, I wish to maintain a 1 nm CPA under all circumstances.

d) For me, I'm going to wait and see if they have seen me and plan to change course, to ensure I don't respond prematurely and interfere with that plan, and therefore will continue to stand on, until I feel there is a need to take evasive action, under Colregs.

And that my friends, is totally subjective. None are wrong. All are Colreg compliant.