AIS ..........MB&Y Feb 2012

[timbartlett]

The argument that if every little boat has it and transmits all the time we will get information overload is inescapable. If this happens ships will certainly filter out B. If you really want to be seen then I think an active radar transponder should be considered to be at least as useful but hey if you can afford everything then have them both, but don't rely even then on the other guy seeing you.

The argument that AIS doesn't guarantee you being seen" is true, but it becomes rather silly if you use uit to support the idea that AIS isn't worth having. It's really is like saying that there is no point having lights on a bicycle mecause you still might not be noticed.

The idea of "information overload" is more credible, but it neglects the fact that AIS B is specifically designed not to cause information overload. OK, the legislators weren't thinking about 7-inch screens -- but if we, on small craft, choose to look at unfiltered data on undersized screens that is surely our problem: it does not relate to the situation on a ship, where the minimum size of the display is laid down by IMO.

Filtering is good. Filtering means discarding unwanted material. So a filter that removes targets that are stationary or do not pose a collision risk effectively serves to highlight those that do. And that is how AIS filters are supposed to work. It is true that it is still a developing technology, and that the regulatiions are still (slightly) ambiguous. But there are no moves afoot to repeal Rule 5 of the colregs, which requires watchkeepers to use all available means appropriate in the prevailing circumstances and conditions.

Deliberately obliterating all small craft from the display because there were so many of them about would be a pretty clear breach of the Rules -- far more so than (say) winding up the sea clutter control a bit higher than necessary.

I'm particularly intrigued by the fact that you suggest active RTEs instead. Surely then the argument must be that if every little boat has and RTE and transmits all the time we will get information overload. If this happens ships will certainly filter out RTEs -- by using S-band radar, for instance? (I know that wouldn't get rid of all RTEs -- but would obliterate all the single-frequency ones!) I don't see how you can separate the arguments in favour of RTE from those in favour of AIS, or vice versa.

 

[DAKA]

This has been one of the best threads I have ever started, I really appreciate everyone's input.

I started not really knowing what it was about and now benefit from all of your experiences.

Thanks

Great to see a little humour getting chucked in as well Benjenbav


Now I need to check if NASA AIS can be added to my system and then buy one

 

[scubaman]

Arrgh, I gave up the print version and subscribed to the iPad one but the Feb issue is still not available

 

[Elessar]

We cruise in the Western Med.
Spain is OK but as soon as you hit French waters, the coast guard is forever calling you.
They see the Class B AIS on their screens and call you every half hour os so.
Its a real PIA!
So much so that we simply switch the transmission off.

Interesting.

Heading south and not stopping I was buzzed by a Portuguese coast guard helicopter and photographed for some time, and was expecting a water borne visit. None came but they did contact me by VHF (by name) and asked a few questions. They asked again each time I got near a TSS, 3 contacts in all.

I then headed east to Malta, and the weather was bad off Tunisia and I needed to anchor for the night. Anchored about 400 m off a beach behind a headland but as soon as I got into territorial waters the CG were on to me. It took a lot of questions and quite a few different people before they were happy, but again not an actual visit. I debated whether to transmit at anchor or switch it off. I elected to transmit.

So 2 things to add to the debate:

I wonder if transmitting actually reduces your chances of a boarding?

What does the panel think about the security issues of transmitting in situations like this?

incidentally I didn't spend long in French waters, only from the Italian border to Antibes, but I wasn't contacted at all.

 

[Hurricane]

Interesting.

Heading south and not stopping I was buzzed by a Portuguese coast guard helicopter and photographed for some time, and was expecting a water borne visit. None came but they did contact me by VHF (by name) and asked a few questions. They asked again each time I got near a TSS, 3 contacts in all.

I then headed east to Malta, and the weather was bad off Tunisia and I needed to anchor for the night. Anchored about 400 m off a beach behind a headland but as soon as I got into territorial waters the CG were on to me. It took a lot of questions and quite a few different people before they were happy, but again not an actual visit. I debated whether to transmit at anchor or switch it off. I elected to transmit.

So 2 things to add to the debate:

I wonder if transmitting actually reduces your chances of a boarding?

What does the panel think about the security issues of transmitting in situations like this?

incidentally I didn't spend long in French waters, only from the Italian border to Antibes, but I wasn't contacted at all.

Not clear if you anchored off Tunisia.
Tunisia is a totally different case - in Tunisia, they would be more interested in "a present" than anything else - believe me.

 

[gjgm]

I havent got AIS yet but feel its something I need to think about however after reading this months MB&Y where it is claimed so many pleasure boats have them you cant see dangers and according to scuttlebutts, commercial shipping sees class B transponders as 'sea clutter' and removes them from the screen anyway

Does anyone have a receiver and do you find it is invaluable or a nuisance ?

Daka
I find it useful for an eyes in the back of my head for the fast red funnels Cowes/Southampton. Otherwise it is pretty useless in Solent as there are so many sailing boats transmitting you cant see anything on the plotter any more, and the alarm is going off every 15 seconds.
Of course channel crossing/cruising it is great.. for couple hundred quid or so, I would def. buy it.

 

[PaulGooch]

This has been one of the best threads I have ever started, I really appreciate everyone's input.

I started not really knowing what it was about and now benefit from all of your experiences.

Thanks

Great to see a little humour getting chucked in as well Benjenbav


Now I need to check if NASA AIS can be added to my system and then buy one

Pete, if you have a plotter that supports AIS and a free NMEA 0183 port, it should work.

Also, remember that AIS needs an antenna. You can use a VHF splitter, but that's not a good way IMO, because if you are using the VHF set, the AIS doesn't get to receive anything. I think the best way is to use another VHF antenna, wired in such a way as to be capable of easily being used as a backup VHF antenna for the radio.

It may also be worth noting the NASA unit is only capable of monitoring a single channel at a time, whereas for a little more money you could have something like a dual channel Comar unit.

We have AIS (receive only) and radar both overlaid on the plotter and as has been said, they both serve slightly different purposes. In busy areas, such as approaching Felixstowe/Harwich, the alarms would be too much, so mine are usually off, unless i'm at anchor. It's nice to be able to "see" the fast windcats approaching from behind, from several miles away. It's nice to be able to "see" the large ships in the channel in the fog and see exactly where they are heading and at what speed. IMO, it adds another layer of information and makes certain situations much easier to interpret.

Class B (leisure boat) transmissions are on the increase, though not plague proportions on the East coast yet. Current filtering needs some improvement. Not sure about the filtering on all plotters, but it's pretty limited on mine. Certainly no option to exclude class B reception. Would be nice to be able to filter out any class B target that isn't subject to what was otherwise an alarm situation. Should certainly be separate filters for Class A and Class B targets.

In short, for the small investment, i think it's worth every penny.

 

[boatmike]

Class B (leisure boat) transmissions are on the increase, though not plague proportions on the East coast yet. Current filtering needs some improvement. Not sure about the filtering on all plotters, but it's pretty limited on mine. Certainly no option to exclude class B reception. Would be nice to be able to filter out any class B target that isn't subject to what was otherwise an alarm situation. Should certainly be separate filters for Class A and Class B targets.
.

About 12 months ago I was shouted down on Scuttlebutt for suggesting that if every little boat in the English Channel transmitted on B we would soon get to saturation point and big ships would turn off B and watch A only. It's interesting that we are now getting posts from users suggesting THEY want to turn off B..... Which of course on all yachtie sets that I know of can't be done. Interesting isn't it that all those new B class transmitters that have been bought not only encourage ships to turn B off but clutters the screen of all the yachties trying to see the ships. Am I just too cynical or what?

 

[DAKA]

About 12 months ago I was shouted down on Scuttlebutt for suggesting that if every little boat in the English Channel transmitted on B we would soon get to saturation point and big ships would turn off B and watch A only. It's interesting that we are now getting posts from users suggesting THEY want to turn off B..... Which of course on all yachtie sets that I know of can't be done. Interesting isn't it that all those new B class transmitters that have been bought not only encourage ships to turn B off but clutters the screen of all the yachties trying to see the ships. Am I just too cynical or what?

Sort of leaves me still thinking too.
@£100 it seemed a useful bit of kit but I assume I now need to spend £400 (engine and splitter) and still have the 'sea clutter' issue.

A few of my raggie mates leave the transponder on even when anchored in Newton Creek so their mates know where the party is at , talk about misuse

 

[RobbieW]

Sort of leaves me still thinking too.
@£100 it seemed a useful bit of kit but I assume I now need to spend £400 (engine and splitter) and still have the 'sea clutter' issue.

If I upgrade my old NASA engine, which only recieves Class A, in the near future (quite likely) I'll PM you - I'll happily take £100 off you for it

 

[Colvic Watson]

If I upgrade my old NASA engine, which only recieves Class A, in the near future (quite likely) I'll PM you - I'll happily take £100 off you for it

How I wish I could turn off class B signals, I want an uncluttered screen with just the big stuff on there. I use AIS a lot to ensure I keep out of the way of ships, calling them when necessary and appreciating the extra information I get over and above RADAR, but class B signals are a huge PITA: I know we will die if a ship collides with us, but I reckon I can survive a collision with Jonny in his "Passing Wind", so what I want to do is set alarms for CPA and TTCPA for ships, but I can't because of all the Passing Winds' that are forever setting off those alarms, so the alarms get deactivated and I have to zoom in close on the screen - but I don't want to zoom in close because a ship at 20 knots is best seen several miles away to be safely avoided, put the damn screen to a scale of 7 miles and it's filled with 37 Bavarias. Thanks chaps, at the height of the season, in a busy port area, AIS is now almost useless. Still valuable cross channel fortunately.

 

[timbartlett]

Sort of leaves me still thinking too.
@£100 it seemed a useful bit of kit but I assume I now need to spend £400 (engine and splitter) and still have the 'sea clutter' issue....

If you really want to do it as cheaply as possible, why not buy the Nasa engine and spend another £30 or so on a dedicated antenna?

Or go for an all-in-one like an ANT200 for about £200?

 

[Hurricane]

If you really want to do it as cheaply as possible, why not buy the Nasa engine and spend another £30 or so on a dedicated antenna?

Or go for an all-in-one like an ANT200 for about £200?

I've got an old Nasa engine that I bought when they first came out.
Mainly to play with to see how well AIS worked.
I'ts connected to my home PC and is still working.

Since those early days, I thought that the Digital Yacht ANT200 would be the one to buy though.
Looks really simple to install and no "faffing" around with antenna or splitters.
Maybe its small antenna will naturally filter out some of the class b stuff as well!!
As I say above IMO class B to class B (well to other leisure craft) ain't that good anyway. I have several experiences of this. On the flip side though, coastal stations seem to pick up my Class B 50 miles away so maybe a ship with a high enough antenna will see more class B transmissions better.

 

[boatmike]

How I wish I could turn off class B signals, I want an uncluttered screen with just the big stuff on there. I use AIS a lot to ensure I keep out of the way of ships, calling them when necessary and appreciating the extra information I get over and above RADAR, but class B signals are a huge PITA: I know we will die if a ship collides with us, but I reckon I can survive a collision with Jonny in his "Passing Wind", so what I want to do is set alarms for CPA and TTCPA for ships, but I can't because of all the Passing Winds' that are forever setting off those alarms, so the alarms get deactivated and I have to zoom in close on the screen - but I don't want to zoom in close because a ship at 20 knots is best seen several miles away to be safely avoided, put the damn screen to a scale of 7 miles and it's filled with 37 Bavarias. Thanks chaps, at the height of the season, in a busy port area, AIS is now almost useless. Still valuable cross channel fortunately.

Made I smile did that! Problem is that there are lots of posts from people who haven't got one. When you have you know it's a total PITA getting an alarm for something you can't see until you are on top of it only to find that its a 20 ft RIB stopped for lunch......

 

[pauljn]

AIS

I havent got AIS yet but feel its something I need to think about however after reading this months MB&Y where it is claimed so many pleasure boats have them you cant see dangers and according to scuttlebutts, commercial shipping sees class B transponders as 'sea clutter' and removes them from the screen anyway

Does anyone have a receiver and do you find it is invaluable or a nuisance ?

I have an AIS class B transponder linked to the plotter on my boat and I would fully recommend it. I don't find the system is overloaded with yachts transmitting, although I do sail on the East Coast and not the Solent. It has a switch for the transmitter which I keep off so that I receive only, unless it's foggy or I'm in shipping lanes.

It's also a good security device I think. The unit itself is hidden away behind the instrument panels and the transmitter switch is also hidden from view, although easily accessed if you know where it is. Therefore when I leave the boat I switch on transmit, so if anyone tried to steal the boat and switched on the instrument panel, I could track her on www.marinetraffic.com

If you go to this website you can see where every ship in the world is, also although it's a bad time of year to assess, you can see how many yachts are transmitting in any area, they show up as a lilac colour. Some people abuse it though, there is a Sun Odyssey 39 thats been transmitting for months from it's mooring at Suffolk Yacht Harbour on the River Orwell

 

[boatmike]

I have an AIS class B transponder linked to the plotter on my boat and I would fully recommend it. I don't find the system is overloaded with yachts transmitting, although I do sail on the East Coast and not the Solent. It has a switch for the transmitter which I keep off so that I receive only, unless it's foggy or I'm in shipping lanes.

It's also a good security device I think. The unit itself is hidden away behind the instrument panels and the transmitter switch is also hidden from view, although easily accessed if you know where it is. Therefore when I leave the boat I switch on transmit, so if anyone tried to steal the boat and switched on the instrument panel, I could track her on www.marinetraffic.com

If you go to this website you can see where every ship in the world is, also although it's a bad time of year to assess, you can see how many yachts are transmitting in any area, they show up as a lilac colour. Some people abuse it though, there is a Sun Odyssey 39 thats been transmitting for months from it's mooring at Suffolk Yacht Harbour on the River Orwell

Its a very interesting website that. Looking at Portsmouth Harbour I count about 32 vessels transmitting right now that are not moving. Currently 5 of these are in Haslar Lake which is a marina. These have to be B I would have thought. Granted that you turn yours off when you leave the boat, but it is clear that many don't. Considering that fitting AIS B to smaller vessels is a relatively new phenomenon, what's it going to be like in 5 years time?

 

[Bandit]

I dont have AIS but intend to fit it shortly with a new set of navaids, I see the problem if every boat on the solent on a busy August Sunday with good weather has an AIS and turn sit on you wont see the water for icons.

I have an Echomax radar enhancer that enhances the signal reflected from my boat, it works like a SeeME radar target enhancer giving a more consistent more solid refelction from my boat.

Surely for both AIS and Echomax in good vis during daylight keep them turned off at sea except when traversing a busy shipping lane.

In fog, in the dark, in really rough weather turn them both on.

I note today there are three private boats in Guernsey marinas with their AIS on which seems a bit pointless.