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binch

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Navigation News, the magazine of the Royal Institute of Navigation, has an excellent article by a Southampton pilot on the subject of the use of AIS in pleasure craft when in confined waters. There is an incompatibility problem which makes AIS of dubious value.
Perhaps YM editor could negotiate with the RIN and reprint the article. It would be valuable to all yotties who care.
 
binch said:
Navigation News, the magazine of the Royal Institute of Navigation, has an excellent article by a Southampton pilot on the subject of the use of AIS in pleasure craft when in confined waters. There is an incompatibility problem which makes AIS of dubious value.
Perhaps YM editor could negotiate with the RIN and reprint the article. It would be valuable to all yotties who care.
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With due respect, that is not quite how I read the article.
First, though, it is worth stressing that it is written by and from the point of view of a pilot a person who, almost by definition, is concerned with conducting a ship only in confined waters, and usually only for first and last few miles of each passage. The circumstances are very different in open water.
Nevertheless, I think it is worth quoting his conclusion:
"To summarise, while AIS is undoubtedly a help to keeping a proper lookout at sea, it is only of benefit when appropriate to the prevailing circumstances and conditions. Because of both the slow refresh rate of AIS B information and the multiplicity of transponders in congested waters, the navigator or pilot is unlikely to use AIS. Like the first voyage cadet, he or she will be keeping a lookout by sight and hearing and radar."

The writer is quite up-front about the positive value of AIS at sea but questions its value in crowded waters such as the Solent.

The key point, I think, is that reference to Rule 5 -- "appropriate to the prevailing circumstances and conditions".

Just because binoculars aren't a lot of use in fog, you wouldn't chuck them overboard, would you? So why reject AIS just because there are some circumstances -- affecting a miniscule proportion of the Earth's surface -- in which it is not appropriate?
 
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I think the implication is that because there are so many small craft in confined areas the biggest ships may switch their receivers to receive only AIS class A to de-clutter their screens.
 
Seven Spades said:
I think the implication is that because there are so many small craft in confined areas the biggest ships may switch their receivers to receive only AIS class A to de-clutter their screens.
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Actually, the writer points out that one of the biggest problems is caused by the escorting tug, whose (Class A) AIS constantly triggers the alarm on the ship. The solution is "... to accept the alarm but not cancel it. Keeping the system "in alarm ...means that other AIS alarms are effectively ignored."

Of course "clutter" is an issue, (particularly on the tiny screens that yachts use), but it's an issue that is not going to be solved if every mention of the word "filter" prompts the "aha it's all useless" response that we so often see.
 
Personally I would only use AIS when vessels are travelling in straight lines, eg crossing shipping lanes when it is a useful tool for an early indication of CPA and whether avoiding action is required.
 
I sail around Gib, very busy. Twice recently in quite thick fog it has been safe to navigate using, amongst other things, AIS.

Extremely useful tool both crossing the Straits and in the Bay.

Very seldom seen on pleasure vessels though so screen is not maxed out.

Can I get by without it? Yes.

Do I find it very useful when fitted? Very much so. Good piece of kit in my opinion.
 
jimi said:
Personally I would only use AIS when vessels are travelling in straight lines, eg crossing shipping lanes when it is a useful tool for an early indication of CPA and whether avoiding action is required.
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I crossed Biscay on a yacht with a Class B transponder recently and it was a huge reassurance during the time we spent in the shipping lanes. However, it had to be switched off as soon as we approached a marina as there were constant 'dangerous target' alarms from moored yachts that had left their instruments on.

There doesn't seem to be any facility to switch off the transponder and keep the receiver on, which would make sense in congested waters.

- W
 
webcraft said:
However, it had to be switched off as soon as we approached a marina as there were constant 'dangerous target' alarms from moored yachts that had left their instruments on.
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I can see some owners keeping the transponder on as they can check the position of the boat from home, but I understand your point and it's something to consider when I get one.
 
webcraft said:
I crossed Biscay on a yacht with a Class B transponder recently and it was a huge reassurance during the time we spent in the shipping lanes. However, it had to be switched off as soon as we approached a marina as there were constant 'dangerous target' alarms from moored yachts that had left their instruments on.

There doesn't seem to be any facility to switch off the transponder and keep the receiver on, which would make sense in congested waters.
- W
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The West Marine set we will buy for our new boat in the USA has the option to turn off the transmission feature as standard and if that were not the case then I would buy a simple receiver only unit. I assume the rules are the same worldwide so other manufacturers should be able to offer the same option?
 
webcraft said:
I crossed Biscay on a yacht with a Class B transponder recently and it was a huge reassurance during the time we spent in the shipping lanes. However, it had to be switched off as soon as we approached a marina as there were constant 'dangerous target' alarms from moored yachts that had left their instruments on.

There doesn't seem to be any facility to switch off the transponder and keep the receiver on, which would make sense in congested waters.

- W
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The Digital Yacht Transponder AIT 1000 has the facility to turn off the transmissions whilst still able to recieve data. It requires a second switch to be installed, details of which are in the User Manual which states...

When configured to place the unit into "Silent mode" each press of the switch will toggle the AIS transmitter on or off. The switch
must be depressed for two seconds to change the state of the transmitter. When the transmitter is off, the yellow "TX Timout"
LED and blue "Silent" LEDs will be illuminated and the transponders position will not be broadcast to other vessels. The position
of other vessels will still be received by the unit.

Peter.
 
Adonnante said:
The Digital Yacht Transponder AIT 1000 has the facility to turn off the transmissions whilst still able to recieve data. It requires a second switch to be installed, details of which are in the User Manual which states...

When configured to place the unit into "Silent mode" each press of the switch will toggle the AIS transmitter on or off. The switch
must be depressed for two seconds to change the state of the transmitter. When the transmitter is off, the yellow "TX Timout"
LED and blue "Silent" LEDs will be illuminated and the transponders position will not be broadcast to other vessels. The position
of other vessels will still be received by the unit.

Peter.
Click to expand...

This is good news. Not all sets have this facility though AFAIK. And of course you still have the problem of persuading weekend sailors in the Solent to turn off transmissions. There are those on here who have in the past defended to the death their right to render the system unuseable for everyone by leaving the transmitter on.

- W
 
While I cannot speak for other brands, the RAYMARINE AIS transponder has a silent mode option - ie the transmitter is switched off.
In fact, as some of you will know from my other postings on the subject, the Raymarine AIS 500 defaults to 'silent mode' on start up.

If in doubt - read the manual!

Cheers,

Michael.
 
Adonnante said:
The Digital Yacht Transponder AIT 1000 has the facility to turn off the transmissions whilst still able to recieve data.

Peter.
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Got it, and it does.
I very rarely use my AIS in the Solent (or other congested areas) for the reasons stated BUT I have turned it on to double check the CPA of something big moving around me. I do not rely upon it solely but use it as another safety feature.
In open water I have it on all the time and the fact that it can 'see' shipping too far away for me to see is a real comfort.
Great bit of kit.
 
I find it really useful when passing Belfast as the fast ferry can be out of sight but, due to speed, can still be on a collision course and soon. I must admit that I cant really see the point in transponding for small pleasurecraft in normal circumstances. Any time I see a picture of a ship turn up on the plotter I expect to look around and see some huge vessel towering over me. It becomes really confusing when a piddly little boat is transponding and makes it very hard to work out who's who. I can see the benefit when crossing lanes or in the wide ocean but if I could transpond I would default to off until required
 
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AIS use

It is an odd feature that electronic anti-collision devices are of main use in crowded waters.
And it is then that one gets overload
My wife and I have sailed over 100,000 miles together, including many ocean crossings, and IMO, one does not need anti-collision features when out of soundings, except in fog, and you do not get much of that deep sea.
The proper thing to do is to keep a good look-out, a very good and conscientious look-out 24/24. I would carry radar, but not for collision avoidance: I use it for making a strange harbour in mediocre conditions.
Echo-sounder, yes.
Don't need anything else.
And yet, on our last voyage, I installed Sea-pro navigation system and after testing, decided to use it.
In the middle of the Dover Strait, in thick fog, the system failed. Question: work on the system, or navigate by steam?
Well, we didn't quite end up on the Goodwins.
Point is that if I had been concentrating from the first on the old steam method, I would have been better off. Eyeballs normally do not fail.
Trouble was that, in my case, I was returning to England because of a badly torn retina.
Problems at sea are never simple: solutions always require true sight, insight and instinct.
 
Things like sailing boats and small mobos are generally easy to avoid with the eye and there is almost always plenty of time to make adjustments etc. I find there is very little need in having them light up my chart plotter screen with their whereabouts. I do find it very useful to keep a track on large vessels, travelling at speed and with reduced ability to manouvre. This is where AIS is useful, backed up with sight bearing compass.
Transponding makes sence to me when crossing lanes as there may be too many of these large ships for me to avoid entering a possible collision scenario and them knowing where I am may become important. Also in deep blue ocean a watch may become lazy and the electronic watch is a good backup and the backup to the backup is letting the other boat know you are there.

I don't have a transponder but do pick up AIS. I have never felt the need to transpond. I, like others, do find it annoying that entering harbours my chart plotter spazzes out with alarms thus reducing the usefull screen size for navigation
 
pmagowan said:
I don't have a transponder but do pick up AIS. I have never felt the need to transpond. I, like others, do find it annoying that entering harbours my chart plotter spazzes out with alarms thus reducing the usefull screen size for navigation
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Isn't this a good argument for getting a bigger screen or better filtering, rather than for denying others the right to make themselves visible?
 
I have a 15inch screen so it is about as big as you can fit. I'm not going to deny anyone their rights but like most systems they need to be used with sense. I can't honestly see any significant benefit to small yachts having a transponder on all the time whereas I can see many problems. It may seem reasonable to those that use them but if the end result is worse outcomes for everyone then it is not a sensible use of technology.
 
I don't have an AIS as yet but intend to get a receiver only for next season purely to keep an eye on big ships and navigation beacons which everyone has ignored.

AIS is just like GPS, DECCA, Radio, mobiles, compass, etc., they are just another item to add to your toolbox of equipment. The problem is that most appear to collect the tools without the understanding of the skills behind the technology and thus do not fully understand the 'where and when' to use it or the 'how to' if it fails.
 
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