WAFIs & AIS

[john_morris_uk]

But it won't mean they are following the rules necessarily. Simply holding course is wrong in quite a few situations, and if that's the result of AIS then we're still at square one. They will still need to actually read the IRPCS just in case they end up motoring across a channel when there is no wind for instance - half of the ships met in this scenario will be stand on vessel and the other half not!

Perhaps his reference to 'following IRPCS' assumes that they will have read and have acquired a working knowledge of them? What you are suggesting is an entirely different point. i.e. Sailors ought to learn IRPCS sufficiently to apply them to the situations that they meet and who is going to disagree with that?

 

[john_morris_uk]

In Ye Olde Days two vessels would spot each other, get close-ish and then one would make a significant change in course to avoid the other, then resume its course. Nowadays vessels can in some cases spot each other miles away and make small changes in course so that the risk of collision, in the old sense, never arises. When a tanker does this with a small change in course it's sensible use of technology - despite being a clear breach of Rule 8. What a yacht does it it's gross irresponsibility..

With respect, that's just being disingenuous. You can't see a ship when its twenty miles away. Its only when its a slack handful of miles away that most people start getting worried and making inappropriate course alterations and by then the rules most certainly do apply. Either stand on and monitor if thats what the rules require (but be prepared to take avoiding action if the other person isn't altering) or make an alteration of course or speed to avoid close quarters and possibility of collision with an emphasis on making a substantial and obvious alteration to make your intentions clear. By the time a ship is a slack handful of miles away, the AIS invariably tells you that they have already seen you and have altered course.

 

[JumbleDuck]

With respect, that's just being disingenuous. You can't see a ship when its twenty miles away. Its only when its a slack handful of miles away that most people start getting worried and making inappropriate course alterations and by then the rules most certainly do apply. Either stand on and monitor if thats what the rules require (but be prepared to take avoiding action if the other person isn't altering) or make an alteration of course or speed to avoid close quarters and possibility of collision with an emphasis on making a substantial and obvious alteration to make your intentions clear. By the time a ship is a slack handful of miles away, the AIS invariably tells you that they have already seen you and have altered course.

The problem remains: at what distance does a risk of collision apply? To a couple of tankers that may reasonable be ten miles or more; to me and you, should we meet on the Clyde this week it would probably be half a mile or so and to racers it might be thirty feet. But what if it's me and a tanker?

I'm heading from Rothesay to Kip. That puts me on a collision course with the Harmony of the Seas, inbound for Greenock. She makes a 2^o change to her course to avoid me - does that count as substantial and obvious? When I get past Towards I turn left to go up past Innellan and Dunoon, as I had always planned ... should I not do that, simply because a big ship has different perceptions?

Simple and honest question: at what range, meeting a large vessel on open waters, would you feel obliged to take on the responsibilities of stand-on vessel (a) if both you and the give way vessel had full AIS (b) if you had an AIS receiver only and (c) if you had no AIS equipment? I'm genuinely interested to know.

 

[GHA]

Absolutely. I think it is arguable that a large give-way ship which makes a 2 degree course change when five miles away to maintain a safe CPA is in breach of the IRPCS my not making a clear change of course.

From memory well offshore it was more like 5 or 10deg, certainly a pronounced dogleg on the AIS track, but usually completed by the time the ship was more than a speck on the horizon. So without electronics a boat would be blissfully unaware that a close quarters situation had even been detected and avoided.

 

[JumbleDuck]

From memory well offshore it was more like 5 or 10deg, certainly a pronounced dogleg on the AIS track, but usually completed by the time the ship was more than a speck on the horizon. So without electronics a boat would be blissfully unaware that a close quarters situation had even been detected and avoided.

Thanks. The problem is that that dogleg might happen long before the yacht's skipper perfectly reasonably thought there was any risk of collision, or need to assess it. What if it happened five minutes before the skipper planned to change course to cross shipping lanes legally?

 

[laika]

I don't think traffic crossing is well taught, in some RYA course at least. Is the bearing on the ship changing? No? Yikes! But do instructors then go on to mention how close a ship that is going to miss you by a mile needs to be before the bearing starts to change appreciably? Do instructors try to teach students to judge the range of other vessels? Will an instructor ever give a response other than "there are no rules of thumb: every situation is different" to questions like "how close is too close?", "when should I consider taking evasive action myself?". Doubtless good instructors do, but the ones I had didn't. Experience eventually taught me, but better instruction might have helped (especially when I specifically asked).

I think AIS can can short cut the required experience in learning to judge traffic. You estimate the range of ships, track their bearing on the handheld, then check your skill and judgment against the AIS. The feedback from the electronics educates and improves the manual navigation skills.

The surprise for me with AIS was that I didn't see vessels making these 1-2 degree course changes from a long way away: Far more seemed to wait until relatively close and make larger (5-10 degrees) corrections. Presumably they've sussed that these WAFIs are too unpredictable.

 

[john_morris_uk]

The problem remains: at what distance does a risk of collision apply? To a couple of tankers that may reasonable be ten miles or more; to me and you, should we meet on the Clyde this week it would probably be half a mile or so and to racers it might be thirty feet. But what if it's me and a tanker?

I'm heading from Rothesay to Kip. That puts me on a collision course with the Harmony of the Seas, inbound for Greenock. She makes a 2^o change to her course to avoid me - does that count as substantial and obvious? When I get past Towards I turn left to go up past Innellan and Dunoon, as I had always planned ... should I not do that, simply because a big ship has different perceptions?

Simple and honest question: at what range, meeting a large vessel on open waters, would you feel obliged to take on the responsibilities of stand-on vessel (a) if both you and the give way vessel had full AIS (b) if you had an AIS receiver only and (c) if you had no AIS equipment? I'm genuinely interested to know.

The answer (which is suspect you will find less than satisfactory) is "it depends". And I think the bridgewatchkeeper (under the circumstances you describe above) is almost certainly capable of working out that you might make an alteration of course when you get to Towards. (I hope you avoid the shallow patch there.)

 

[JumbleDuck]

The answer (which is suspect you will find less than satisfactory) is "it depends". And I think the bridgewatchkeeper (under the circumstances you describe above) is almost certainly capable of working out that you might make an alteration of course when you get to Towards. (I hope you avoid the shallow patch there.)

Actually, I think "it depends" is a completely satisfactory answer. Rigid systems of rules never work; there always has to be a sensible system of human interpretation.

I draw 1.3m, so the shallow patch isn't an issue!

 

[john_morris_uk]

Actually, I think "it depends" is a completely satisfactory answer. Rigid systems of rules never work; there always has to be a sensible system of human interpretation.

I draw 1.3m, so the shallow patch isn't an issue!

I think we are getting close to actually being in agreement. How worrying is that?

 

[JumbleDuck]

I think we are getting close to actually being in agreement. How worrying is that?

Terrifying, and completely against the spirit of these forums. What do you think of CQRs?

 

[john_morris_uk]

Terrifying, and completely against the spirit of these forums. What do you think of CQRs?

I used one for years. I always thought they were brilliant. I now have a Spade and because I paid for it with my hard earned cash I now think that the Spade is brilliant.

 

[JumbleDuck]

I used one for years. I always thought they were brilliant. I now have a Spade and because I paid for it with my hard earned cash I now think that the Spade is brilliant.

How very true. My CQR cost £25 plus another £25 for regalvanising and I think it's great too!

 

[lustyd]

Perhaps his reference to 'following IRPCS' assumes that they will have read and have acquired a working knowledge of them? What you are suggesting is an entirely different point. i.e. Sailors ought to learn IRPCS sufficiently to apply them to the situations that they meet and who is going to disagree with that?

My point was that if previously these boats would turn away in every situation then they clearly have zero understanding of the rules and therefore it's likely that they will continue either doing that or standing on in every situation as they watch to see if the ship moves first - essentially playing electronic chicken with the ships.

 

[SimonFa]

Having just done my first return channel crossing with an AIS connected to OpenCPN doing CPA, having done four return trips without one I have to say it was fantastic. I'd say it reduced my stress levels around the TSSs from about 7 to 2.

One thing I did notice, though, was the difference heading and course made when looking at the CPAs on the laptop and then at the boats on the water. As the difference was at times 25deg it made a big difference to my perceptions of where the CPA was going to be compared to where it was predicted. Although I used to use a compass and try to figure out what was going on the crew would only be looking at headings and I'm sure I made some course changes that were unnecessary based on that perception because the crew were getting edgy.

 

[awol]

It's a mile and a half wide. Does that really count as a narrow channel?.

North of Brodick the charted channels are ~1.5 cables wide in each direction and ships are constrained to follow them. Leaves plenty of room for you to faff about while "not impeding". Heading from Rothesay to Kip the "Harmony of the Seas" ain't going to make a 2 degree turn to avoid you 'cos she would go outside the channel. Playing with the Calmac/Western/Argyll ferries is another game entirely and I suspect if you regard 30' as reasonable for a racing yacht then you may feel uncomfortable with how little and late they change course for you.

 

[Heckler]

There is a difficulty with assessing the risk of collision as it is different for each vessel dependent on manoeuvrability. The large ships are likely to detect things early and react early but in doing so they can fail to make a manoeuvre which is obvious to a small yacht. AIS can aid in detecting this manoeuvre. A small boat might react much later but will likely make a coarse change in the region of 90 degrees. It may be tacking to go to somewhere other than it is pointing and thus it was never going to collide although a projection of its original course would suggest otherwise.

Going to the IoM this year, had my RO4800 watching AIS and saw a big bu gger coming at right angles to me. The RO info told me that he was changing course, you could see his rate of change on the radio screen. He went behind me.
S

 

[pmagowan]

North of Brodick the charted channels are ~1.5 cables wide in each direction and ships are constrained to follow them. Leaves plenty of room for you to faff about while "not impeding". Heading from Rothesay to Kip the "Harmony of the Seas" ain't going to make a 2 degree turn to avoid you 'cos she would go outside the channel. Playing with the Calmac/Western/Argyll ferries is another game entirely and I suspect if you regard 30' as reasonable for a racing yacht then you may feel uncomfortable with how little and late they change course for you.

I was pleased to see in my last cruise up the West Coast of Scotland that the ferries did take early avoiding action and made it quite clear to me they were doing so. It was even clearer with the aid of AIS.

 

[rotrax]

As a previous poster has said, every situation is different.

In a previous life I needed to make decisions in a fraction of a second, as with the agenda here, to avoid collisions-but with other competitors or scenery.

The wrong decision could be life threatening.

I find it quite easy to make judgements at sea, the time frame is quite relaxed compared to what went before.

I have, however, no misapprehensions about the results of getting it wrong!

First mate and I have done plenty of Channel crossings, most at night, which we find easier.

If adjusting speed and direction does not fix the situation we circle, heave to or stop.

We leave it quite late before making a move, and then it is a big one that leaves no room for any misunderstanding of our intentions.

So far so good.......................................................................................