Collision Avoidance, Cones of Uncertainty, and Appropriate CPA

[evm1024]

Originally Posted by ramblinrod

Yes it was.

The OP suggested or recommended that all rec boaters be trained, skilled, and licensed for navigation and collision avoidance to the level of those on the bridge of large commercial vessels.

I am not going to go back through all of these posts to find it, but it was most definitely posted in this thread.

I disagree with this premise to the bottom of my sole.

There you go again. Let me refresh your memory. I don't mind looking it up. I don't expect you to because it does not support your position.

Dockhead said in post 1037:

I think the moral of the story is that if you want to mix it up with ships in busy waters, you need to have decent skills, not so much lower than what you would need on a ship. You just have no business being out there, if you think you can just bumble along and rely on ships to do all the heavy lifting.

Discussions like this make me think again that we really ought to be required to have licenses, after proving that we are competent in the several essential skill sets.

The phrase "ought to" means necessary or would be a good thing. That is a long way from suggest or recommend. And, in addition given that it is a reaction to some really sloppy thinking in regards to boating we can view is as a rhetorical device.

Then you go on to state that Dockhead said: licensed for navigation and collision avoidance to the level of those on the bridge of large commercial vessels when he actually said: have licenses, after proving that we are competent in the several essential skill sets

I mean come on here Rod. Talk about distortions! Is your memory that bad? Talk about jumping to conclusions.

He said: not so much lower than what you would need on a ship. But as you will note it is a level lower than required on ships.

Then you conclude with: I disagree with this premise to the bottom of my sole.

Of course you disagree - You changed the argument to something much easier to defeat and claimed that Dockhead said it. Thus Dockhead is wrong. Strawman Rod strikes again.

[jackdale]

Originally Posted by ramblinrod

I disagree with all of my sole.

I believe that there is a minimum acceptable level of competence in navigation and collision avoidance, but the level expected on the bridge of a large ship, is considerably higher than in the cockpit of a small cruising sailboat.

The professionals aboard ships are expected to be able to use all of the features of all of the applicable nav and collision avoidance instruments with a very high degree of skill and efficiency.

The rec boat skipper, isn't even required to have the instruments mandated on the commercial vessel.

Much higher degree of relevant and related competence and capability expected on the large commercial vessel.

I think you just destroyed your own assertion.

On the bridge on a large ocean going vessel you will find:

1) Radar - which will have ARPA which will allow the bridge to determine CPA and TCPA by simply reading a screen

2) AIS - Which will also tell the bridge the type of vessel, it length, couse and speed, CPA, TCPA as well as its destination.

3) An ECDIS with redundant displays and power supplies.

Your assertion that recreational vessels do not necessarily have those capabilities means that the crew of the recreational vessel will need to know how to identify a vessel by days shapes and lights, as well as be able to determine the risk of collision using a hand bearing compass. They will also require frequent horizon sweeps. All while being in the cockpit and while navigating the vessel with the simplest of instruments. That requires a high level of competency.

[Lodesman]

Originally Posted by ramblinrod

Hmmm, recent discussion raises a new question.

If a recreational boater, takes a bunch of courses and passes exams, are they now required by maritime law to use that knowledge, where a rec boater who hasn't isn't?

IOW, if John Doe has no special training and James Doe decides to get his Master's License, would a maritime court hold James to a higher level of competence expectation than John?

I know I would if I were the Judge or Jury.

Originally Posted by ramblinrod

I never suggested that anyone was ignorant of any law.

To change the question from:

a) Will the higher trained person be held to a higher expectation of competence?

to...

b) Will ignorance of the law get someone incompetent off the hook?

...are two completely different questions.

.

Good grief Rod, do I have to explain what you said, to you again?

If James has a Master's license which gives him knowledge that John doesn't have, then John is ignorant (relatively). If they are in court, then it stands to reason that a law has been broken. Law doesn't have a gradation of infraction - it's broken or not; guilty or not guilty. James' knowledge of that law does not work against him any more than John's ignorance of it gives him protection from it. It's called 'logical deduction.' You should try it.

[Paul Elliott]

Originally Posted by ramblinrod

The professionals aboard ships are expected to be able to use all of the features of all of the applicable nav and collision avoidance instruments with a very high degree of skill and efficiency.

Rod,

This is irrelevant to the current discussion. All the fancy nav gear in the world will be of no help if the other vessel is darting around with no concept of the rules of the road. But this is apparently your position otherwise why even mention it?

[El Pinguino]

Originally Posted by jackdale

I think you just destroyed your own assertion.

On the bridge on a large ocean going vessel you will find:

1) Radar - which will have ARPA which will allow the bridge to determine CPA and TCPA by simply reading a screen

2) AIS - Which will also tell the bridge the type of vessel, it length, couse and speed, CPA, TCPA as well as its destination.

3) An ECDIS with redundant displays and power supplies.

Your assertion that recreational vessels do not necessarily have those capabilities means that the crew of the recreational vessel will need to know how to identify a vessel by days shapes and lights, as well as be able to determine the risk of collision using a hand bearing compass. They will also require frequent horizon sweeps. All while being in the cockpit and while navigating the vessel with the simplest of instruments. That requires a high level of competency.

Class B doesn't tx destination and with Class A the bridge team have often failed to update the destination info.

[Exile]

Originally Posted by ramblinrod

Throughout this thread you have requested that I defend my opinion to great lengths, many, many times, and I have done my best.

Here, I have asked you to cite a reference to support your opinion.

You have chosen not to.

I assume that either:

a) Your expressed desire to help (above) is insincere.

b) You cannot cite a reference to support your opinion.

This causes me to question the credibility of your expressed sincerity, and opinion on the matter.

My position on the subject, is that...

"In general, there is a higher level of competence expected from a professional than from an amateur."

I suspect this applies to the expectations of navigation and collision avoidance competence between typical professional mariners in charge of a large commercial vessel, and a husband and wife team cruising a small sailboat.

They both have to follow applicable regulations, but there would be an expected possible or probable difference in competence levels.

I do not profess for one second to be as competent a navigator and skilled collision avoidance expert, as compared to those having professional mariner accreditation of licences, and qualified to be in command of a large commercial vessel.

I do believe I am sufficiently competent to handle my rec boat in any circumstances I may reasonably encounter.

I would expect that is quite common, and in fact reasonable, and that there is no real reason or benefit for a rec boat skipper to seek the competence level of a commercial vessel ranking officer, unless they seek that professional position or out of simple personal interest, and legislation mandating that level of education, experience, and licensing for all (as suggested by another poster), would be disasterous to the recreational boating community.

The best analogy I can offer, is that I want to be able to treat myself and crew with first aid, should anyone become ill or injured aboard.

I have read many first aid books and taken several first aid courses, and have taken a pretty significant St. John's Ambulance certified marine first aid course. I do not believe I should need to become a board certified doctor to be sufficiently competent to meet the first aid needs of my vessel and crew.

I understand that as an amateur, if I render first aid to an individual and they claim I have caused them harm, that I am protected by law, whereas a professional medical practitioner, could be found guilty of malpractice for doing exactly the same thing; I assume because there is a higher level of competence expected of a professional vs an amateur.

In your last para. you are describing the so-called "Good Samaritan" law. This has nothing to do with the respective liabs of an amateur vs a pro mariner in an incident btwn a rec. and a comm. vessel. For the umpteenth time, you are conflating standards that are imposed based on a particular type of vessel, vs responsibilities that are shared equally btwn ALL different types of vessels. Your answers lie not from me but from the Colregs, the only link to which I recall you citing in this entire thread. But even that apparently failed to induce you to read, study, and return to the thread with questions if need be. I guess you were too busy making up your own rules & theories, and of course calling those who try & help you various derogatory names. As I've said repeatedly, it's your loss.

[ramblinrod]

Originally Posted by Exile

In your last para. you are describing the so-called "Good Samaritan" law.

Your are correct, it is the "Good Samaratin Law" that protects the amateur and not the professional.

Oh wait a minute, right, because the professional is expected to be more competent.

[jackdale]

Originally Posted by El Pinguino

Class B doesn't tx destination and with Class A the bridge team have often failed to update the destination info.

That is true. And sometimes the team does not update the status; I am seen moored vessels in mid South Atlantic. That does not negate the point I am making.

[nigel1]

Rod, I believe the call was for recreational cruisers to be competent with regards to the Colregs, which is completely different to having the same competency as a licensed commercial watchkeeper.
I hold a Masters Foreign Going ticket, and no way would I expect a recreational boat user to have the same competency as I have, but I would expect them to be competent with regards to Colregs, know their obligations and know the various light and shape configurations.
Learning the Colregs is not rocket science.
With regard to radar, the Colregs only states that proper use should be made of radar if fitted and operational. I think any boat owner who has a radar, should make proper use of it.

[Uricanejack]

Some of you have mentioned the "PCOC".
Its a Canadian licence requirement. As to whether or not its worth the plastic its printed on or the 40$ fee. I wont comment.
It sets the minimum standard of knowledge required by the operator of a small boat in Canada. Unlike other jurisdictions where there is no required minimum standard. It s effectively a state issued licence. Even the mighty YM is not a license. (Unless the Commercial endorsed)

The level of knowledge expected can be seen in the Canada safe Boating Guide.
You will find its is just a basic understanding of the simplest concepts in the Colregs. Some local Buoyage. and some safety equipment.

The courts in Canada will apply the standard of due diligence. Should a court case result due to a collision between a commercial vessel and a small vessel.

Due Diligence? How would a reasonable person expect a reasonable person to reasonably act. The level of knowledge and certification will certainly form part of the question was due diligence exercised and will apply.

So would it be reasonable to expect the operator of a small vessel with a PCOC to understand the full meaning of the requirement to not impede or rule 2 or the actions of a stand on vessel?

Change the operator of the small vessel to MM. ask the same question and the answer about what might be reasonable may be different.

[Uricanejack]

The original premise of this thread. Referred to the 1 degree alteration and 180ft.
I have not read the original context in the original thread, I haven't found it.
Most of you seem to have concluded this was a reckless or foolish statement.
You are all to focused on hard numbers.

Passing close astern is very different from passing close ahead.
If you alter course early rather than later you don't have to alter course nearly as much to have the same effect.


As has been stated just do the math. Apply the geometry or trig.

The numbers are just rather extreme examples of a fairly simple perfectly safe and reasonable approach to collision avoidance.

[Paul Elliott]

Originally Posted by Uricanejack

The original premise of this thread. Referred to the 1 degree alteration and 180ft.
I have not read the original context in the original thread, I haven't found it.
Most of you seem to have concluded this was a reckless or foolish statement.
You are all to focused on hard numbers.

Passing close astern is very different from passing close ahead.
If you alter course early rather than later you don't have to alter course nearly as much to have the same effect.


As has been stated just do the math. Apply the geometry or trig.

The numbers are just rather extreme examples of a fairly simple perfectly safe and reasonable approach to collision avoidance.

Jack, the issue with that one-degree course alteration resulting in the 180-ft crossing the stern is this:

We were discussing fast ships and slow small boats. Assume an 800-ft ship going 18 kts, and our small boat doing 5 kts. Our courses are at 90 degrees to each other, and we realize that if we do nothing we will hit the ship. Because we have experience racing sailboats in close quarters and have full control of our "pucker factor", we determine that a one-degree course change will allow us to pass close behind the ship. Passing 180 feet behind the stern was claimed to be OK, since no paint was traded. No collision, so no COLREGS problem.

(Have I got that right???)

In this scenario, if we alter course for that 180-ft clearance, we are still essentially heading straight for the ship. All the ship can see is that we are closer than 220 ft as the bow rushes by us. Our one-degree course change has certainly gone unnoticed. Of course, they probably can't even see us at that point. Even assuming that we can control our course and speed this accurately, and the bow-wave and propwash of the ship don't spin us around, it's likely that the ship (even if the ship is stand-on) will have maneuvered to avoid our suicidal charge long before we get this close.

So, in the case above, that one-degree course change resulting in a 180 ft crossing is both dangerous, and not in keeping with COLREGS. Yes, do the math. When the numbers become this extreme it is neither simple nor safe.

[Dockhead]

Originally Posted by Uricanejack

The original premise of this thread. Referred to the 1 degree alteration and 180ft.
I have not read the original context in the original thread, I haven't found it.
Most of you seem to have concluded this was a reckless or foolish statement.
You are all to focused on hard numbers.

Passing close astern is very different from passing close ahead.
If you alter course early rather than later you don't have to alter course nearly as much to have the same effect.


As has been stated just do the math. Apply the geometry or trig.

The numbers are just rather extreme examples of a fairly simple perfectly safe and reasonable approach to collision avoidance.

Yes, let's get back to the original premise of this thread. I see it went way down a couple of rabbit holes while I was traveling.

The whole point of the original thread was this -- how do we account for what we can't know, when we are doing collision avoidance maneuvers? What we can't know can be represented with a cone of uncertainty, which was actually plotted by someone some pages back in the thread.

A one degree alteration from five miles out, say, might really change a collision course to a safe pass, if you do simple math and figure the distance represented by that one degree over five miles. The only problem with this is that we don't know to that degree of certainty where either we or the ship will be five miles later. In fact, if you think about it, a one degree alteration of course is meaningless, totally meaningless, anyway, because we can't hold a course to that degree of accuracy, nor can you expect the ship to hold its course to that degree of accuracy. Then you add in speed, and errors in estimating position, etc., and you soon see that making a one degree alteration of course is completely useless.

As to the 180 foot pass -- I think we can all agree that passing close behind can be safe -- if you can see the transom of a ship moving much faster than we are, then no matter how close or how far you are, there is no problem, guaranteed. But the whole problem with this is getting there. How do you set it up? How close to the BOW of the ship, would you have to get, in order to pass 180 feet behind, when there is such a different in speed? What does it even LOOK LIKE, being on a course to pass 180 feet behind a fast moving ship?

And so there is such a thing as a safe CPA -- and a safe CPA is one which you can set up from a safe distance away, and which provides enough margin of error that it can absorb the uncertainties in calculating your maneuver. 180 feet is not a safe CPA under any circumstances, when crossing in open water with a fast moving ship, because there is actually no such thing -- we don't have enough information to set it up. It's the same as a collision course or 180 feet passing ahead. You have to set up a crossing so that you know you are passing, the way you think you are passing, and that needs to be a distance bigger than the cone of uncertainty around the positions of the two vessels when they cross.

That's what we were talking about, and I think most people on here got it.

[evm1024]

Originally Posted by Lodesman

You really don't have a clue. Professionals have malpractice insurance. The good Samaritan laws are there as an inducement to lay people to provide emergency medical aid in the absence of professional medical help, by indemnifying them. There is no equivalent in the marine world.

Exactly so.

Good Sam laws do not apply here but that is not what Rod was trying to show.

He likes to show that A implied B therefore C implied D without regard that A and C are unrelated.

Further, If we were to allow any relevance to the Good Sam laws and Boating then we will also have to consider that the Good Sam laws do not protect you if you exceed your level of training.

Try a Tracheotomy as a First Aid-er and you will have a very complicated life.

So it sounds like Rod is advocating that all recreational boater who wish to navigate in waters where advanced skills are needed must have a professional certification.

[transmitterdan]

Originally Posted by ramblinrod

Your are correct, it is the "Good Samaratin Law" that protects the amateur and not the professional.



Oh wait a minute, right, because the professional is expected to be more competent.

That's not the reason for Good Samaritan laws. The laws were created to encourage strangers to render aid at the scene of accidents. It has nothing to do with relative competence.