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

The Seawitch and the Esso Brussels. What did I learn form the Federal Court Decision
Both ships are always blamed to some extent.
The Seawich's insurance company had good lawyers.
I cant remember the proportion of blame I just remember being shocked by it. My recollection of the reasons given might be a bit off.
Apparently the Esso Brussels did not try to warn the Seawitch or attempt to Slip her cable,
If you want to learn, read the NTSB not the Federal Court.

Put yourself in the OOW on anchor watch on the Esso Brussels. Or Better yet another ship in the same situation today. Get out of that one.
The Court and Lawyers will still find blame.

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

Please provide data to support this claim? Often, really? What are you basing this on?

It doesn't take much for Class B AIS to reach further than the 2nm visible nav lights!

:confused:

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

Data comes from own observations and conversations with commercial mariners, who often complain that they don't receive or receive only sporadically our AIS transmissions. This is not a scientific study, so if you have better data, I would be glad to see it. It's possible I'm being too pessimistic about it, but I do observe and hear about problems fairly often - enough for me to believe that we should check, before assuming that our AIS data are being received at an appropriate range.

My own set is carefully installed (I'm an Extra Class ham, and while I'm maybe not a top expert on radio installations, I do know a few things, and possess a SWR/power meter, good soldering kit, and expensive crimp tools) and had to change antennae a couple of times and remake some connectors before I got it working properly. I can't count how many AIS sets I've seen on other boats which are connected to ancient half-rotten thin coax with connectors falling off, often through cheap splitters. My pet peeve is the disconnect connectors at the mast step, often lying in bilge water, which the owner often doesn't even know exists. I keep a bag of good UHF connectors on board so I can help other cruisers with these problems.

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

I dunno, DH, saying that class B AIS is unreliable because some boats may have bad installations is stretching it a bit IMO, and then to say it is often the case begs for some supporting data. You could make the same argument about nav lights or radar reflectors, couldn't you?

I don't now about where you sail, but in the last few years here on the East coast of Oz the number of class Bs has grown rapidly. What I observe is reception at 8-15 miles distance on a regular basis, and what I do not see is boats suddenly popping up on the screen a much closer ranges. These observations are made from a masthead antenna/splitter setup, and I suspect that the much higher dedicated antennas on ships superstructures might well have even better results.

I can't speak for others, but I know that I and many of our cruising friends routinely do inter-yacht checks for AIS reception, and from my observations our range is in the better part of the distribution, but hardly unprecedented.

Finally, comparing AIS to a radar reflector... well, the miserable performance of most reflectors reported in the tests that I have seen would lead me to dispute your statement; i believe that for ship/yacht interactions the AIS is a better aid to collision avoidance, looking at it from both sides of the interaction. Obviously, both together are better yet, and that is what we should strive for.

Jim

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

Let's assume a 'dodgy' installation, as you claim. Let's say only 1 of every 5 AIS transmissions are getting out. On a 6kt boat, that is every .25nm (10 min. per nm). Let's assume the GPS reception on the transmitting unit is compromised and the GPS position is off by 50m (pretty rare to be more than that with any GPS fix). If the AIS antenna/connections are 'dodgy', it's only getting out 4nm. Still better than the nav lights!

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

I must have expressed myself badly!

I'm not saying that AIS is bad -- far from it. I think it's the best thing that ever happened to collision avoidance.

Nor am I saying that AIS Class B Mark 1 is 1% or 10% or 50% unreliable -- I don't have such data. All I can say is that it is not rare, for us not to be seen on AIS.

So all I'm saying is that AIS, great as it is, is not guaranteed to make you seen every time. Having AIS is not a reason to neglect nav lights or radar reflectors. Nav lights are not optional in any case -- we are required to show them, and to show them correctly. I would expect you would both agree with this, don't you?

And -- that it's worth checking from time to time, how you are showing up and at what distance. You might be surprised, even if your set is well installed. A badly installed AIS set does not typically just have reduced range and successful transmission rate. They often just drop off for minutes or hours at a time. Meanwhile, they may still be receiving just fine, which gives a false sense of security.

Also, bad installation is not the only reason your AIS messages may not be getting through -- Class B Mark 1 uses a different access scheme which can cause some of the messages to get lost in crowded waters. So I also think it's a good idea to upgrade to Mark 2 Class B -- SOTDMA -- which is now being sold at reasonable prices. SOTDMA has the same access scheme as Class A with the same priority, and has 5 watts of power compared to 2. The power is always good, but it's not nearly as important as a good antenna and good feedline. It's the access scheme which is the main advantage of SOTMDA Class B.

I'm changing out my own AIS set this winter, but I'm skipping over Class B SOTDMA and going straight to Class A, now that this is also available at a reasonable cost.

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

The more things you do to be seen and properly identified as to vessel, course and speed the better. AIS, radar reflectors, proper lighting, VHF set to the right channel all help the other vessels understand the situation. Each vessel must know and follow the Colregs. Collision avoidance is a system. It takes all the available parts to make it work the best.

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

Indeed, very true, and very well stated. :thumb:

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

I have never had a ship say they couldn't pick up my class B AIS, and judging from their behavior over the last 30 years, they are much more likely to change course to avoid me if I'm transmitting.

As far as picking up incoming AIS signals goes, all the fancy antennas, coax, and connectors isn't going to help if you have a noisy LED tricolor mounted next to your masthead antenna.

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

Yes, you mischaracterized. Please don't paraphrase if you can't do it accurately. That is a strawman by definition, changing what one said, and then arguing against that.

My point was, that commercial vessels are held to different standards. They must carry radar, they must carry AIS. No choice. There are many other standards and regulations that apply to commercial vessels that do not apply to rec vessels.

Additionally I stated that according to Colregs, everyone is required to proceed at safe speed, depending on conditions, including proximity and congestions of obstructions and other vessels.

So if a commercial ship, who stands to lose money (a lot of money) if they slow down, chooses to maneuver from a long distance out, to avoid congestion, that is their choice and a wise financial decision.

Did I say a rec boat sailor should expect that (implying base all decisions on that)? NO. Not at all.

Please do not put words in my mouth (or any posters) so that you can make good arguments against them. You are then, in fact, arguing with yourself.

Instead, just make your point, without implying it is argument against someone else's, when it most definitely is not.

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

Then what was your point? If you, as a recreational boater, cannot know, and therefore should not assume what a commercial vessel is going to do, you can't expect that they will manoeuvre just to avoid a risk of collision situation where they're 'stand on' to a recreational vessel.

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

I disagree.

This is like saying if one wishes to drive their automobile on a road which includes people who are professional race care drivers, Joe Average needs to learn the skills identical to the pro race car driver.

This is like saying if anyone wants to work on the electrical system of their boat, they should not, unless they have an marine electrician certification.

Oh, shoot, wait a minute, I do agree with that.

Well, not really, my position is that one should not work on the electrical system of their boat, if they do not have a solid grasp of the applicable standards and have reasonable practical skills to apply them. Not necessarily as high a knowledge and skill set, just reasonable.

And this is the standard that I believe is proper for rec boaters with respect to collision avoidance...An understanding of the applicable regulations (Colregs) and reasonable skills, meaning, the ability to plot a course, hold a course, change course, identify risk of collision, and follow Colregs.

I don't believe a rec boater needs to read additional guides or plot relative motion of vessels around them. Simply monitoring other vessels for closing constant angles, by eye if visibility is good, or radar or AIS if otherwise, and without radar/AIS, dead slow with appropriate sound signals, and perhaps VHF securite calls, if one gets caught.

To expect every rec boater to be "licensed" and perform navigation to the same level as aboard large commercial ships is ludicrous. Some may wish to and that's fine, but to mandate it for everyone, preposterous.

First of all, it would be an incredible infringement on Civil liberty, with BIG BROTHER, attempting to protect the public from themselves to a micro degree. It simply doesn't work. No matter what training and licensing is mandated, there will be some that learn and practice well, and many that don't. So really, bureaucracy has been increased, but safety really has not.

To be absolutely safe, everyone could wear a full body condom. Nothing could get through that sucker. Of course, they would suffocate and die.

To increase bureaucracy in rec boating with additional mandatory training and licensing would simply reduce the accessibility to the public and freedom that it represents and so many cherish.

I'm completely against that.

Please show me anywhere where one suggested one should. Posting INCREDIBLY OBVIOUS statements like this, does not really support your argument for mandatory training and licensing for all.

No doubt. I can't think of a profession that does not complain about the skills of amateurs. It is absolutely natural and to be expected.

If I accept your contention that no-one should be allowed to navigate a rec boat without a Master's license, would you accept a position (not mine) that no-one should be allowed to modify or repair a rec vessel unless they were licensed to do so? It is exactly the same thing. It would fly like a ton of bricks. It would make boating less accessible to the masses. Even if it would likely be safer, it would not be better.

I don't believe this is true. I think most responsible rec boaters, learn the applicable regulations and take reasonable steps to stay safe and not put other vessels in peril.

I understand that this is your opinion. You made it long ago. I disagree. I think most boaters know enough to be very careful around large fast moving vessels. We have not all steered the "Sara", where everyone else gets out of the way, like Captain Ron.

Throughout this thread, I have made some pretty bold statements about crossings, which theoretically can be done, but nobody in their right mind would do it, if they didn't have to.

I disagree, most boaters I encounter do it right. Some don't, and I don't believe any amount of mandatory training or licensing will change that.

I don't know how often this actually happens. How often do fatal collisions between rec boats and commericial ships occur, one in 10,000,000 crossings? Isn't one about 100 times more likely to be hit by lightning sailing in Florida? The old argument, that "if it saves one life, it is worth it". In my opinion, this is total BS. There has to be very good reason for mandated specialized training and licensing, and I just don't see it here.

Of course, and I want boat owners to stop butchering their electrical systems and risking setting themselves on fire, but mandating special training and licensing to perform is not the way to go.

I don't think anyone is suggesting one shouldn't, we just disagree what level of skills are needed.

I have never sailed the "Straights of Dover", but I have sailed in some pretty congested areas, with lots of traffic going in every direction. I have yet to encounter a situation where basic boating skills and some experience, built up over time, would not handle pretty much any situation.

As I instruct every new boat owner, "Take Baby Steps". Scaring the bejeepers out of one self or crew, will ruin it for the rest of your life, faster than anything else.

In principle, this a realistic approach, too -- many sailors, maybe most, sail in waters where you can just stay out of the channels and fairways. But if you do get into a crossing situation in open water, it is not right to think that you can just rely on the ship to deal with it. .[/QUOTE]

Again, I don't think anyone in this entire thread has suggested this, except jokingly.

Alas, what level of skills and knowledge, and how these are gained, should be up to the individual to assess.

There are some who have purchased a boat and circumnavigated the world, with no prior experience (Tania Abby is the first that comes to mind, who did it in a Contessa 26.)

Should legislation not have allowed her to do this? That would be a huge, huge, mistake in my opinion.

I may consider her actions foolhardy, but it's her life, we only get one, and this ain't no dress rehearsal.

One could argue, that she may have put other's lives in jeopardy. This may be true. But nobody died. I only wish I had the brains, guts, naiveté, or whatever it was she had that enabled her to achieve this impressive feat.

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

With all due respect - I think that we should grant some grace to others on the thread. If we are going to hold others to be exact then we should be exact ourselves. For example I could say about the comments I quoted:

Yes, you misstated the rules. Please don't state rules if you can'd to it accurately.

I find it very offensive to have it stated this way. Perhaps it is a style thing.

Anyway the AIS rules are listed below.

In addition I think that if we are going to claim violations of logic then we should all be very sure of our own logic. What is good for the goose is good for the gander.

In my own opinion Commercial vessels are not held to a different standard than Recreational vessels. The Standard is a single body of laws and practices that covers the breadth of the boating world.

Heck, if we were to claim that there are differences for commercial vessels then sailboats are held to a different standard than power boats in that so far as when 2 sailboats are in a crossing situation there are different rules that apply to only sailboats.

COLREGS is COLREGS not COLREGS for Commercial and COLREGS for Recreational.

In my opinion to hold Commercial vessels to a different standard in ones mind is to shirk responsibility to some greater or lesser degree for our own responsibilities. It is the nature of us humans to ascribe greater culpability to others and less to our'selves when we hold them to a greater standard. This is a failure of logic to be avoided.

Here are the rules from the US. Others places in this wide world are much alike. The casual reader will note that there are no requirements for a large number of commercial vessels to carry AIS.

(b) AIS carriage.

(1) AIS Class A device. The following vessels must have on board a properly installed, operational USCG Type-approved* AIS Class A device:

(i) A self-propelled vessel of 65 feet or more in length, engaged in commercial service.

(ii) A towing vessel of 26 feet or more in length and more than 600 horsepower, engaged in commercial service.

(iii) A self-propelled vessel that is certificated to carry more than 150 passengers.

(iv) A self-propelled vessel engaged in dredging operations in or near a commercial channel or shipping fairway in a manner likely to restrict or affect navigation of other vessels.

(v) A self-propelled vessel engaged in the movement of –

(A) Certain dangerous cargo as defined in subpart C of part 160 of this chapter, or

(B) Flammable or combustible liquid cargo in bulk that is listed in 46 CFR 30.25–1, Table 30.25–1.

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

I don't know why everyone is so worked up about this

Your to darn right a pro should be held to a higher standard
They are accepting payment to ensure the safety of any passengers or crew on thier boat
The higher the certification the higher the expected standards
Just plain old common dog

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

You are quite right that a "pro" is held to a higher level standard of performance. (not to a different set of rules) That is not the issue.

To rephrase - each mariners actions are evaluated on what they should know, what they do know and what actions they took. Pro or recreational.

The problem as I understand it is that some appear to be saying that as recreational mariners we only have to know the basics. And that we should depend on professional mariners to make sure they do not run us down whatever we do.

I might rephrase that as "I don't need no stinking advanced boating skills. So don't tell me anything I don't wanna know".

And further that because they do not want to know (or to be told that they should know) then none should know.

My own mantra is - Plan, Project, Execute. For others it might be - Go, React.

When a recreational mariner decides to cross a VTS they should know something about VTS.

I thought the real point of the thread was to help those who wanted to know figure out well in advance how to handle crossing situations with fast moving ships. Rather than reacting to a near collision in the last 5 or 10 minutes.