Collision Avoidance -- Dealing with Multiple Targets

[Dockhead]

Originally Posted by windshadowthree

Not quite the answer you're looking for but I find being caught in the middle of a sailboat race, when the race caught up with us, while we were sailing, in a fairly narrow passage, with lots of tacking going on, was a great and exciting exercise in collision regulations, and sailing etiquette so as not to get in the way of the racers.

Not an answer, but a nice comment!

[Dockhead]

Originally Posted by Stu Jackson

Dockhead,

I've been reading your contributions here for many years. I especially was taken by the CTS looong discussions and bookmarked the "short version" which linked back to the long one.

I see this effort as a logical extension of that topic and your other contributions from your sailing experiences across the congested Channel on your summer jaunts, and even your local sailing around the IOW. I wish you well in developing the material.

Many of the responses here indicate to me that the comments are from skippers who are unfamiliar with your travels and experience, you know, the "Why try to rewrite Colregs?" comments. That, of course, is clearly NOT what you are attempting. It is, however, the nature of forums.

I wish you the very best in your efforts on this highly interesting subject. As I have mentioned before, I will sometime soon cross the Strait of Georgia and need to implement your CTS discussion. Thanks again so very much for that great learning experience.

All the best, Stu

What a kind thing to say! Thank you! I have also followed and enjoyed very much your comments over the years. Enjoy the Georgia Straits. That's really hard core sailing - I hope I will see them some day.

[bmz]

I know from the facts in your question your main concern is for when you are in a heavily trafficked commercial area where the majority of the targets are class A, to whom you must give way (although I noticed here, as I have in other threads, that many sailors erroneously think that they have the right-of-way over large commercial vessels).

However, for the majority here whose multiple target situations occur where they are many class B targets and very few class A targets, I have a recommendation: focus on the class A target and ignore the class B targets (especially where the class A targets are large freighters who are not maneuverable, but can be quite fast). Where you have only one or two class A targets it is usually quite easy to avoid them.

The class B targets are all small and maneuverable, and if you are a sailing vessel most of them will have to yield to you. In any event, when you get close enough you will both see each other easily and the burden vessel should yield( :-) ).

[GeneM]

My experience is from the 70s and 80s on ships. The rules say decreasing range and constant bearing is risk of collision, which kicks in the steering and sailing rules for two vessels.
If three or more vessels are in risk of collision then it's special circumstances and there are no stand-on or giveway vessels. Each must do what they can to avoid collision.
If there is a collision, a judge will sort out if all did what they could to avoid collision.
Today, modern plotters with integrated radar should be able to figure a regular risk of collision or special circumstances. I'll bet that a good program could even recommend a best course and speed and warn of necessary changes.
I was often in a swarm of fishing boats, so I just watched the radar and the visual aspect and could see when things were getting tight. We would mark the screen with a grease pencil. The key is to leave a way out. We usually couldn't adjust speed without about 15 min of notice to the engineers.

[Dockhead]

Originally Posted by bmz

I know from the facts in your question your main concern is for when you are in a heavily trafficked commercial area where the majority of the targets are class A, to whom you must give way (although I noticed here, as I have in other threads, that many sailors erroneously think that they have the right-of-way over large commercial vessels).

However, for the majority here whose multiple target situations occur where they are many class B targets and very few class A targets, I have a recommendation: focus on the class A target and ignore the class B targets (especially where the class A targets are large freighters who are not maneuverable, but can be quite fast). Where you have only one or two class A targets it is usually quite easy to avoid them.

The class B targets are all small and maneuverable, and if you are a sailing vessel most of them will have to yield to you. In any event, when you get close enough you will both see each other easily and the burden vessel should yield( :-) ).

This thread is not about this, but I'd just like to note a few of the errors in this post:

1. No one ever has right of way at sea. There is no such thing.

2. There is also no such thing as a burdened vessel, since the 1972 revision of the COLREGs.

3. You get in as much trouble for smashing into a vessel broadcasting Class "B" as one broadcasting Class "A" so ignore them at your peril.

3. In open water, smaller slower vessels are actually LESS maneuverable, that is, less able to change a dangerous CPA than larger faster vessels (contrary to the common misconception of small boat sailors who have never been on the bridge of a ship).

4. You don't always "give way" to commercial traffic -- in some situations and for a certain phase of certain crossings, you are obligated to hold your course and speed so that they can maneuver.

As I said, this thread is not at all about this, so if you want to start such a discussion, please start a different thread.

[Juho]

Here's one possible general rule of thumb for dealing with multiple targets.

The problem occurs when we are the give-way vessel, planning to make a change in our course (usually course, not speed), and the planned change of course would lead to a conflict (that can't be handled later, after getting clear of the first vessel) with another vessel. In the second conflict we would again be the give-way vessel, or the other vessel would have some problems changing course. I also assume that we can not solve the problem by changing the course slightly more.

In this situation we could maybe solve the problem by changing the course twice some essential amount. But that could be already too much to be comfortable. It is quite possible or probable that it would make ore sense just to slow down. In a confusing situation that is probably a good solution in any case (better than speeding up or changing course in some complex way).

The simple algorithm is thus as follows. Find a solution (change of course) for the most urgent problem (first vessel). If that leads to a conflict with other vessels (that can't be solved by turning a bit more), slow down.

This algorithm should be a good rule of thumb for most situations. There are also such (complex) scenarios that have no such solution that would include only changing course. Therefore slowing down is sometimes needed. If slowing down doesn't help, start the algorithm from the start again (with lower speed), and slow down more if there still is no easy way to change course. Problem solved ... almost ... or at least alleviated .

Another way to formulate this rule. "If in doubt, slow down an think again".

[bmz]

Originally Posted by Dockhead

This thread is not about this, but I'd just like to note a few of the errors in this post:

1. No one ever has right of way at sea. There is no such thing.

2. There is also no such thing as a burdened vessel, since the 1972 revision of the COLREGs.

3. You get in as much trouble for smashing into a vessel broadcasting Class "B" as one broadcasting Class "A" so ignore them at your peril.

3. In open water, smaller slower vessels are actually LESS maneuverable, that is, less able to change a dangerous CPA than larger faster vessels (contrary to the common misconception of small boat sailors who have never been on the bridge of a ship).

4. You don't always "give way" to commercial traffic -- in some situations and for a certain phase of certain crossings, you are obligated to hold your course and speed so that they can maneuver.

As I said, this thread is not at all about this, so if you want to start such a discussion, please start a different thread.

Your response has me at a loss for words(almost).

To start--yes this thread is about this; you said: "Another situation is when you are dealing with multiple targets at once.
Anyone have any good technique or insight to share?"

My response was to share my technique for dealing with multiple targets.

Moreover, you focused on irrelevant minutiae while ignoring substance. You took what I said out of context so that you could create a strawman to knock down; to wit:
1)You attack my use of the terms "right-of-way" and "burdened." Others on this thread used those terms for good reason--they are commonly used and everyone here fully understands them. So what's your point--to get a gold star in terminology?
2) I did not advise "ignoring" class B vessels; I said "The class B targets are all small and maneuverable, and if you are a sailing vessel most of them will have to yield to you. In any event, when you get close enough you will both see each other easily and the burden vessel should yield" More importantly you can't get into "as much trouble" crashing into a class B vessel as a class A vessel; crash into a class A vessel, and you will die.
3) the very worst is your suggestion that small sailing vessels have the right away over large commercial vessels. You are wrong--dead wrong.
[url]http://wow.uscgaux.info/Uploads_wowII/095-45-01/Rules_of_the_Road_for_Sailboats.pdf
https://www.boatsmartexam.com/knowle...rules-boating/
https://americanboating.org/bigger_on_the_water.asp.

[Stu Jackson]

Originally Posted by bmz

Your response has me at a loss for words(almost).

To start--yes this thread is about this; you said: "Another situation is when you are dealing with multiple targets at once.
Anyone have any good technique or insight to share?"

My response was to share my technique for dealing with multiple targets.

Moreover, you focused on irrelevant minutiae while ignoring substance. You took what I said out of context so that you could create a strawman to knock down;>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>

Except that he did not make up a strawman, he did point out factual mistakes in your comments. Many of those incorrect comments have been repeated by 'sites like the ABC you quoted, to the chagrin of many of us. "Rules of the Road" and "Law of Tonnage" are so stupid because they fly in the face of what the actual responsibilities are as defined in Colregs. I suppose the RotR and tonnage nonsense may be helpful to Joey-Sixpack before he heads out on his Formula 280, but those guys don't read much anyway. But to perpetuate incorrect information, and then to demean factual information is hard to understand.

1972 was how long ago?

[sck5]

My favorite experience with too many large ships moving in different directions. On New Years Eve a couple of years ago we crossed from Lake Worth to the Bahamas overnight. Just before midnight I saw what seemed like a hundred (actually it was more like 6 or 7) large ships converging on where I was headed. After a few tense moments I figured out a way to thread through them when suddenly they all started shooting off fireworks! Apparently, a bunch of cruise ships conspired to make a bigger show for their passengers by meeting on the edge of the Gulf Stream.

Happy New Year!

[bmz]

Originally Posted by Stu Jackson

Except that he did not make up a strawman, he did point out factual mistakes in your comments. Many of those incorrect comments have been repeated by 'sites like the ABC you quoted, to the chagrin of many of us. "Rules of the Road" and "Law of Tonnage" are so stupid because they fly in the face of what the actual responsibilities are as defined in Colregs. I suppose the RotR and tonnage nonsense may be helpful to Joey-Sixpack before he heads out on his Formula 280, but those guys don't read much anyway. But to perpetuate incorrect information, and then to demean factual information is hard to understand.

1972 was how long ago?

This is exactly my point; Dockhead is going to get you and others like you killed. If he doesn't exercise his responsibility better, he should not be a moderator here.

[Stu Jackson]

Originally Posted by bmz

This is exactly my point; Dockhead is going to get you and others like you killed. If he doesn't exercise his responsibility better, he should not be a moderator here.

Others like me??? Excuse me, but I fail to see your point. At all. Care to explain?

[Snore]

Back to the original question.

When dealing with multiple targets -#1 is ColRegs. However since multiple target can be a s@@t show I will get on the radio. The example I use in classes is crossing the GS in a sailboat and dealing with the conga line of cruise ships out of Miami and Ft Laud. Given the speed differentials and that the ships sometimes all go slower than normal to make their destinations around sunrise, getting by safely is a challenge.

One radio call and obliging ships will gladly open a gap in the conga line for the give way vessel to get through.

[Dockhead]

Originally Posted by Juho

Here's one possible general rule of thumb for dealing with multiple targets.

The problem occurs when we are the give-way vessel, planning to make a change in our course (usually course, not speed), and the planned change of course would lead to a conflict (that can't be handled later, after getting clear of the first vessel) with another vessel. In the second conflict we would again be the give-way vessel, or the other vessel would have some problems changing course. I also assume that we can not solve the problem by changing the course slightly more.

In this situation we could maybe solve the problem by changing the course twice some essential amount. But that could be already too much to be comfortable. It is quite possible or probable that it would make ore sense just to slow down. In a confusing situation that is probably a good solution in any case (better than speeding up or changing course in some complex way).

The simple algorithm is thus as follows. Find a solution (change of course) for the most urgent problem (first vessel). If that leads to a conflict with other vessels (that can't be solved by turning a bit more), slow down.

This algorithm should be a good rule of thumb for most situations. There are also such (complex) scenarios that have no such solution that would include only changing course. Therefore slowing down is sometimes needed. If slowing down doesn't help, start the algorithm from the start again (with lower speed), and slow down more if there still is no easy way to change course. Problem solved ... almost ... or at least alleviated .

Another way to formulate this rule. "If in doubt, slow down an think again".

Thanks-- that's an actual procedure, and interesting.

A couple of people have mentioned slowing down.

Just want to mention that although taking way off is specifically mentioned in the COLREGS, you need to be really sure that taking way off will have the effect you desire -- of defusing the situation. To be sure about that, you have to do a certain amount of work. So in my opinion, taking way off should not be a quick automatic reaction to a potential conflict.

All the more because less speed means less ability to maneuver -- less ability to increase the CPA. Outside of harbors and approaches to harbors, power to control a crossing is all about speed, and not at all about a high ROT.

Ships almost never take way off in a risk of collision situation, and neither do I, unless it's a situation in a harbor or approach to a harbor when I'm approaching a fairway. But even then, a change of course is usually just as effective, and without the effect of losing your ability to make distance between you and some dangerous spot in the water.

[Dockhead]

Originally Posted by bmz

Your response has me at a loss for words(almost).

To start--yes this thread is about this; you said: "Another situation is when you are dealing with multiple targets at once.
Anyone have any good technique or insight to share?"

My response was to share my technique for dealing with multiple targets.

Moreover, you focused on irrelevant minutiae while ignoring substance. You took what I said out of context so that you could create a strawman to knock down; to wit:
1)You attack my use of the terms "right-of-way" and "burdened." Others on this thread used those terms for good reason--they are commonly used and everyone here fully understands them. So what's your point--to get a gold star in terminology?
2) I did not advise "ignoring" class B vessels; I said "The class B targets are all small and maneuverable, and if you are a sailing vessel most of them will have to yield to you. In any event, when you get close enough you will both see each other easily and the burden vessel should yield" More importantly you can't get into "as much trouble" crashing into a class B vessel as a class A vessel; crash into a class A vessel, and you will die.
3) the very worst is your suggestion that small sailing vessels have the right away over large commercial vessels. You are wrong--dead wrong.
[url]http://wow.uscgaux.info/Uploads_wowII/095-45-01/Rules_of_the_Road_for_Sailboats.pdf
https://www.boatsmartexam.com/knowle...rules-boating/
https://americanboating.org/bigger_on_the_water.asp.

OK, thanks for your technique.

If you want to argue about what the COLREGS mean, please start a different thread.

[Dockhead]

Originally Posted by sck5

My favorite experience with too many large ships moving in different directions. On New Years Eve a couple of years ago we crossed from Lake Worth to the Bahamas overnight. Just before midnight I saw what seemed like a hundred (actually it was more like 6 or 7) large ships converging on where I was headed. After a few tense moments I figured out a way to thread through them when suddenly they all started shooting off fireworks! Apparently, a bunch of cruise ships conspired to make a bigger show for their passengers by meeting on the edge of the Gulf Stream.

Happy New Year!

That's a great story!