Challenge: Collision Avoidance!

[hellosailor]

Dan-
I agree with your concern but "The swan has 2 boats abaft the beam and should not turn in front of them." may not be what I'm talking about. I do not suggest turning IN FRONT OF THEM (that is, across their bows).
I suggest an immediate coming about, doing a 180 in place as best possible, and at no time coming across the bow of either of them. Now, I don't know how fast a Swan 82 comes about at speed. I've driven a 110' converted water lighter (remade into a survey ship) and you could spin the helm on that, go out for coffee, and then come back to see if it had noticed. But many sailboats are more agile than that and will come about in just a few boatlengths, especially if encouraged with both engine and sails.

Which one were you thinking of?

[Pelagic]

You bring up valid points Dan which is why this scenario is a great test for prioritising and understanding the “intent” of the RULES.

If OS had been a 1500 ton fish packer instead of a nimble Swan, my actions would have been more formal but nonetheless much the same.

12 minute time line

First Minute: try and communicate your intentions with overtaking vessels and request that Traffic assists in communicating with ALL Foreign ships behind you.

At same time start reducing speed so as to make tightest turn you can. (Inform skipper if you are the Mate of emergency.)

If skipper sound general alarm and post extra lookouts on stern of vessel with handhelds on private working channel.

Switch to hand steering with helmsman following your commands

Second Minute: Allow Traffic to get a handle on this and monitor their instructions to both OT’s to slow down IMMEDIATELY.

Third Minute:

Worst Case…… If Traffic is unable to communicate as soon as look-out confirms that he can see the lights of OT-2… I would sound one short blast to indicate my turn to starboard….. and then 5 short and rapid blasts to wake them up.

If not in sight of one another…….no maneuvering sound signal as it could cause confusion and panic

Once clear of OT-2, focus on OT-1 to give maximum CPA on reciprocal.

Best Case….both OTs and OS are talking with each other and Traffic.

I start my tight turn to starboard earlier confirming personally “Green to Green” with OT-1 and “Red to Red” with OT-2.

Then by prior agreement the much slowed down OT vessels would turn around each other keeping safe distance until they are heading away from P-1.

"Traffic" would be very busy.... slowing down and perhaps turning around other vessels that were originally behind us in the inbound lane, while handling the panicked calls from 300 fish boats who heard Traffic relay a PAN PAN call on all working channels.

The very LAST thing I would do Dan is to go into that minefield of fishing nets.

It would be a free for all in there when the fleet recognises it’s danger, hear this heavy tonnage ship repeatedly sounding the danger and NUC signals with its booming horn.

If you got fouled in a cut away net, you would be a sitting duck. (Or a Swan in this case)

[Lodesman]

Originally Posted by Pelagic

The Student OT-1 is ok as he should also do a hard 180 also but should wait about 1 minute for you to pass him going the other way.

Explain why OT-1 should wait for you to turn and pass him before he turns?

Student OT-2 is screwed because he has wandered outside the traffic separation scheme in an attempt to pass both OT-1 and OS and will be punished for this.

So OT-2 gets punished for breaking one rule, but you get away with breaking a couple - proceeding the wrong way in a traffic lane; altering towards a vessel abaft your beam (if not visible) or not maintaining co and sp with regard to an overtaking vessel (if visible).

As Paul pointed out, the rogue Super-Containership (P-1) had a habit of actually following you if you tried to finesse it by “assuming” the NUC rogue would maintain its course and speed. The simulator Instructor and DOT examiner would modify the generated target’s data to make life miserable if you tried to speed ahead of it or do a slight alteration.

Yeah, I suppose P-1 could alter to port, but it is far more likely that he is doing everything possible to turn stbd or slow himself down, if not stop altogether. I've always hated contrived scenarios in the sim. Something that would not be apparent in the sim - when you make your hard stbd turn you're going to heel to port, and your radar mounted high on the mast of your Swan is going to lose paint on OT-1 and OT-2, so if they're hidden in the fog, you won't see OT-1 turning and you'll plow into his bow. Also your turn will nullify all ARPA info. I don't see exacerbating the more immediate close quarters situations as the best solution to a future problem, especially since you'll be stuck between two fishing fleets, going the wrong way against incoming traffic, with a NUC containership bearing down on you for the next half hour. But to each his own, eh?

[Ex-Calif]

I have been "resisting" trying to solve the other boat's problems. That is take actions that help them. The risk is I start busting rules and then if anyone collides later, in the cold flourescent light of court, I get roasted.

I agree with Pelagic about the fishing nets - but it might be the last crappy option. I think the vectors I drew are accurate so there is no harm in stopping for a minute or two and re-assess. Stopping doesn't break any regs and doesn't bring my boat any closer to the scene of the accident. OS is also the most maneuverable vessel in the game. This provides options to quickly get bearing on anyone else.

Is it presumptous of OS to tell Traffic their intentions and expect Traffic to issue instructions to the OTs to watch out for me especially as I am the "second" person to start breaking regs?

I am curious to explore the role of "Traffic" - If they issue instructions are skippers compelled to comply? If they issue instructions to OS contrary to a 180 degree turn is OS compelled to comply?

BTW - I know we only get the data in the original post but arguably we would have initial bearing info to PS. That changes a lot of decisions for everyone.

[Pelagic]

Lodesman, I hope the formal explanation answered some of your concerns but I will expand on some of your comments.

Originally Posted by Lodesman

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Explain why OT-1 should wait for you to turn and pass him before he turns?

He doesn’t have to but if we were communicating with each other, it would be the prudent thing to do, to get my nimble craft out of the way of the bigger OT ships and if I was in command of OT-1 that is what I would want, while slowing down for a tight turn and talking to OT-2 about their avoiding manoeuvre.

So OT-2 gets punished for breaking one rule, but you get away with breaking a couple - proceeding the wrong way in a traffic lane; altering towards a vessel abaft your beam (if not visible) or not maintaining co and sp with regard to an overtaking vessel (if visible).



That is where I believe you and others go wrong Lodesman… I am not breaking any rules. I have communicated my intention to Traffic Management and hopefully got communication and agreement from the OT vessels.

(b) In construing and complying with these Rules due regard shall be had to all dangers of navigation and collision and to any special circumstances, including the limitations of the vessels involved, which may make a departure from these Rules necessary to avoid immediate danger.

By following Rule 2, which supersedes all the Rules following it, you are attempting to survive a real and present danger and may I say maintaining “co and spd to allow OTs to pass you at minute 6 and 7 would be suicidal when you have an unguided missile coming towards you at 32 knots for your remaining 5 minutes. (but each to his own..eh? )

Yeah, I suppose P-1 could alter to port, but it is far more likely that he is doing everything possible to turn stbd or slow himself down, if not stop altogether. I've always hated contrived scenarios in the sim.


I know what you mean, but I guarantee that the pressure you are feeling when the DOT examiner is monitoring your actions, is very real. It is a simulation, but it does point out weaknesses in understanding the Rules, that skippers can learn from and my intent here was to have some fun discussing it.



Something that would not be apparent in the sim - when you make your hard stbd turn you're going to heel to port, and your radar mounted high on the mast of your Swan is going to lose paint on OT-1 and OT-2, so if they're hidden in the fog, you won't see OT-1 turning and you'll plow into his bow. Also your turn will nullify all ARPA info.

Your comment about Radar problems indicates that maybe you haven’t spent much time working radars in fog so here are a few tips.

Practise using your radar in daylight in different weather conditions using the ranges below 1nm to see how by manually tuning… dramatically reducing gain, clutter etc… you can paint consistent targets that have good definition for your radar in close quarters. …Makes a huge difference!

ARPA is pretty useless in close quarters with large targets as the processor can pick returns first from the bridge, then the bow, then along the hull, confusing the vectors being calculated.

Instead learn to always use your Radar on North up presentation so that when you make a quick course change it is not slewing around giving you a fuzzy return (even for only a few seconds)

If your radar is tied in with GPS, switch to ground stabilized True Motion when you are doing close avoidance work. That way, you quickly see the target make a course change if you use the trail function at short intervals to keep a record of the targets movement.



I don't see exacerbating the more immediate close quarters situations as the best solution to a future problem, especially since you'll be stuck between two fishing fleets, going the wrong way against incoming traffic, with a NUC containership bearing down on you for the next half hour. But to each his own, eh?

Lastly, I hope I am not coming across too “pedantic” about all of this. Granted I have had a lot of formal training and experience and tend to write that way, but my intent with these challenges is to learn what others think and have a friendly exchange.

At the end of the day we each make our own decision and live with it.


So hopefully someone else will come up with another tricky collision avoidance scenario more in sailing or racing oriented that will test our impulses….(don’t forget the bikini babes!

[Pelagic]

Hi Dan, good points in your last post.

First to clarify in the Swan scenario, I actually alerted “Traffic” to the quickly developing situation and once they got an explanation from P-1 of the problem, I then advised them of a solution which would take me out of danger with about 10 minutes to spare.

When I did the 60D St calculation for immediately turning around, I never mentioned contacting VTS of my intentions, because Hellosailor had already included that.

I would have followed protocol and given them my intentions under Rule 2

When you read my “formal” response if I was on a 1500 ton fish packer, my decisions on the time line pretty much matches up with your analysis to slow down for 3 minutes before taking action, if I got no response from the OTs.

Originally Posted by Ex-Calif

I am curious to explore the role of "Traffic" - If they issue instructions are skippers compelled to comply? If they issue instructions to OS contrary to a 180 degree turn is OS compelled to comply?

I can’t quote any specific Law but when you take a Pilot onboard a ship it is always “Pilot’s advice, Captain’s orders”, so I imagine it is the same with Vessel Traffic Control.

Ultimately it is the Captain’s responsibility and I imagine if he successfully chose to follow his own analysis and decision process to avoid a casualty, it would be difficult to fault him.

In this situation, Traffic also has limited liability (same as a ship’s Pilot) so they would never tell a ship to maintain course and speed into a known danger.

They would listen to your intensions then advise that you slow down and use extreme care in making your 180 turn only when you felt it was safe to do so.

In other words the buck would always stop with you.

[Ex-Calif]

Originally Posted by Pelagic

They would listen to your intensions then advise that you slow down and use extreme care in making your 180 turn only when you felt it was safe to do so.

In other words the buck would always stop with you.

That was the answer I was hoping for. As a pilot it's pretty much the same rules. ATC can give orders but as Pilot in Command you get the call. You better have darn good reasons at the inquiry.

BTW - I don't think you are being pedantic. I think this was really fun and I think traffic wise there were a lot of things to consider.

[Pelagic]

Thanks Dan, I hope someone can draw up a tricky racing scenario..and let the weekend lawyers loose

[Lodesman]

Originally Posted by Pelagic

Your comment about Radar problems indicates that maybe you haven’t spent much time working radars in fog so here are a few tips.

You've clearly misunderstood my comment. As you make a tight turn you heel - as you heel your radar antenna will be tilted and on the stbd side will be aimed at the sky. You will lose paint on a vessel that is 400 yards astern of you in the critical moment that you are turning towards it. If you've ever used an ARPA, you should be well aware that when you make any large changes in course or speed, it takes some time for the ARPA tracks to "settle down". Simulators are notorious for not having the real-life limitations - no blind arcs, no interference, no running rabbits etc. Thank you for your concern, but having spent thousands of watches on the Pacific coast, I am quite familiar with the use of radar in fog.

[Eleven]

Thanks Pelagic. It's good to think about these things in the dry.
And so many different answers from experienced and qualified 'masters'.

Is the real message that reducing speed is the first thing for all three then re-assess; decide; advise and take action? Though speeding up suits some??? And avoiding in the first place by using shallow draft and accepting slower trip due to limited speed through fishing traffic in patchy (worsening) fog?

I've got the English Channel on my doorstep and Southampton Waters my front path.

We little fella's have manouvreability, a super tanker takes 13 nm to do a crash stop? and the only way to better that is to slew to a stop (hand brake turn) highly unpredictable! Cutting my speed extends thinking time and watching time. The following boats are already aware and avoiding me by their track and Traffic messages. Turning after they pass is an option if P1 fails to do something but I'd rather dodge one predictable (not manouvreing but may slow down) ship than three.
I'd expect OT1 and OT2 to slow to improve manouevring ability but they'll be past me by then. Last thing they want to see is me turning across their bows.

[Lodesman]

Originally Posted by Pelagic

That is where I believe you and others go wrong Lodesman… I am not breaking any rules. I have communicated my intention to Traffic Management and hopefully got communication and agreement from the OT vessels.

(b) In construing and complying with these Rules due regard shall be had to all dangers of navigation and collision and to any special circumstances, including the limitations of the vessels involved, which may make a departure from these Rules necessary to avoid immediate danger.

I must have missed that part in the Rules that says communication with VTS absolves you of your responsibility to follow the Rules
What immediate danger is presented by a vessel over 6 miles away? Or put another way - you'd turn towards a vessel 400 yards away to avoid a vessel 6 miles away!?!?!? Good luck using that in court.

[Pelagic]

Originally Posted by Lodesman

You've clearly misunderstood my comment. As you make a tight turn you heel - as you heel your radar antenna will be tilted and on the stbd side will be aimed at the sky.

Are you saying that on a sailboat when heeled over, their Radar does not work? That has not been my experience.

You will lose paint on a vessel that is 400 yards astern of you in the critical moment that you are turning towards it.

When OT-2 is abeam of you at CPA 0.15nm which is about 300 yards their distance is opening away because of superior speed if you waited the 6 minutes till then to make your turn.

If you turned at minute 3 it would be a further .25nm or about 500 yards away from you (total 800 yards)

A Swan can easily turn 180* in 10 seconds at slow speed in 1.5 boat length (I know as I have delivered them in that size range) that is about 41 yards which….. with an 800 yard margin is a comfortable manoeuvre.


If you've ever used an ARPA, you should be well aware that when you make any large changes in course or speed, it takes some time for the ARPA tracks to "settle down".


Again, anyone who depends on navigating with ARPA within 0.5nm has never taken the course or read the manual which makes that very warning on its limitations.

I can then understand your reluctance to change course.

Simulators are notorious for not having the real-life limitations - no blind arcs, no interference, no running rabbits etc. Thank you for your concern, but having spent thousands of watches on the Pacific coast, I am quite familiar with the use of radar in fog.

Radar awareness aside,…..When I read back on your first answer to speed up Lodesman, it shows that you didn’t have a full appreciation of the danger.

1- Assuming that P-1 would steer a straight course and not wander more to port.

2-That the OT vessels were even aware of the danger (Radar on 12nm…. Music playing loud, old man asleep)

Some trivia…..Collision Avoidance technology by Radar was based on a concept of “PADs” (Planned Areas of Danger) copyrighted originally by Sperry. It was meant to actually show your areas of risk with any target you are interacting with. (Not the surgical vector line which most mariners mistakenly believe in)

A NUC vessel closing in on you at 36 knots when you speed up already has a huge PAD with collision now in 10 minutes.

How long do you wait before taking action, 4 minutes? 6 minutes?... By then the PAD has surrounded your ship.

When does it become an immediate danger and what options do you now have left?

What happens if the 2 OTs wake up at about that same time….do you really want to be in that mix with a Swan when everyone is in a panic and are trying to outrace an NUC mountain doing 22 knots?


Rules? ……Forget Traffic read the legal precedence of Rule 2 cited in Cockcroft and Lamjeller that state….

“If a departure from the Rules is necessary to avoid immediate danger, a vessel would not only be justified in departing from them, but may be expected to do so”

Your priorities are right to deal with OT-1&2 first, but if you cannot communicate with them get turned around as soon as you safely can in the early stages.

That is my advice (and the DOT examiners agree)

[Pelagic]

Originally Posted by Eleven

Thanks Pelagic. It's good to think about these things in the dry.
And so many different answers from experienced and qualified 'masters'.

Is the real message that reducing speed is the first thing for all three then re-assess; decide; advise and take action?

Absolutely Right!

Though speeding up suits some??? Wrong!

And avoiding in the first place by using shallow draft and accepting slower trip due to limited speed through fishing traffic in patchy (worsening) fog? Not recomended in those conditions

I've got the English Channel on my doorstep and Southampton Waters my front path.

We little fella's have manouvreability, a super tanker takes 13 nm to do a crash stop? and the only way to better that is to slew to a stop (hand brake turn) highly unpredictable! Cutting my speed extends thinking time and watching time. The following boats are already aware and avoiding me by their track and Traffic messages. Turning after they pass is an option if P1 fails to do something but I'd rather dodge one predictable (not manouvreing but may slow down) ship than three.

I'd expect OT1 and OT2 to slow to improve manouevring ability but they'll be past me by then.
You and Traffic should try to alert them, but quite often some ship's keep sloppy watches. You have to be prepared for that

Last thing they want to see is me turning across their bows.

You are not turning accross their bow.!...what they would see on their radar is your relative vector pointing behind you as they are overtaking you. It would grow as you slowed down, then slew a touch for ten seconds before growing more as you slowly make way in the other direction between the 2 ships.

It is not a big deal!

Hope that helps and everyone is entitled to their opinion ....even if they are wrong!!

[Lodesman]

Originally Posted by Pelagic

Are you saying that on a sailboat when heeled over, their Radar does not work?

How did you possibly get that out of what I said??? Go back and read it again.

A Swan can easily turn 180* in 10 seconds at slow speed in 1.5 boat length (I know as I have delivered them in that size range) that is about 41 yards which….. with an 800 yard margin is a comfortable manoeuvre.

Assuming OT-1 isn't turning to stbd or OT-2 isn't turning to port (or both). In your world we only assume that vessels overtaking you will maintain their courses while the vessel with stuck rudder and throttle will manoeuvre wildly - OK I get it now

Again, anyone who depends on navigating with ARPA within 0.5nm has never taken the course or read the manual which makes that very warning on its limitations.

Again I am amazed at your ability to read something that I did not write. I already stated you would lose paint on the OTs, so as you should know the ARPA plots would drop on them. I'm talking about the ARPA plots on P-1 and any other vessels (such as the nearest targets in the fishing fleets).

[QUOTE]
Radar awareness aside,…..When I read back on your first answer to speed up Lodesman, it shows that you didn’t have a full appreciation of the danger.

1- Assuming that P-1 would steer a straight course and not wander more to port.
[/QUOTE]

I never assume anything as you suggest. That's why we continue to monitor the situation and adjust as necessary.

2-That the OT vessels were even aware of the danger (Radar on 12nm…. Music playing loud, old man asleep)

And despite this hazard, you want to steer between them...

Speeding up isn't just to avoid P-1 - it keeps you ahead of the OTs, you'll open from OT-1 and OT-2 won't be overtaking you for 30 minutes, so you have all your options open - you can bail out to stbd or even port if necessary.

What happens if the 2 OTs wake up at about that same time….do you really want to be in that mix with a Swan when everyone is in a panic and are trying to outrace an NUC mountain doing 22 knots?

Same question with your solution - with my solution the Swan is out ahead of the mix and will stay there even if the OTs speed up to 20 kts.

Since you like Cockcroft and Lameijer, then you should have seen this passage: "This Rule does not give any vessel the right to take action contrary to the Regulations whenever it is considered to be advantageous to do so. A departure is only permtted when there are special circumstances and there is immediate danger. Both conditions must apply. The departure must be of such a nature as to avoid the danger which threatens."

[Morgan Paul]

Hey Pelagic, I dissagree with you about turning before the 2 freighters overtake the Swan.

Thanks for taking the time to post the challenge. It was fun