AIS issue

[C2 RIBS]

The latest RYA info shows
"Growing concern that ships are able to filter out AIS Class B transmissions
However, more recently, the Royal Institute of Navigation and indeed the RYA has noted growing concern among the leisure boating community that despite the revised radar performance standard, ships are able to ‘filter out’ AIS Class B transmissions from small craft. Such a facility is open to misuse and ultimately makes the fitting of anything other than a receiver a fairly pointless and expensive exercise."

If this is the case then clearly any of us opting for AIS could be filtered out of a ships radar view even though we would still see them or is this RYA info misleading?

[Erin]

I had to read the article a couple of times to try and understand it. In one paragraph it stated that no manufacturer produces a unit that can filter out the signals and then in the next breath says that units can be set to filter.

I would have thought that there would be risk of negligence aimed at any captain who decides to filter out the signal if it results in a collision. I also don't see where the logic of clutter comes in either. Surely the time when there is 'clutter' is the busiest and most risky for collison and they would want all info available on other vessels tracks that they can get.

[SPR]

AIS can be displayed in Radar or a separate screen.

The RYA article stated AIS B can not be filter at the native level, but could be filtered at the RADAR screen where most of the traffic is displayed.

The 15 min transmission delay on AIS B, means you could well be on a vessel before your position has been updated...on the ships screen.

So in theory you better not being on the system, and the radar will filter out "unreliable" / "Historic" information from radar.

Looks like the Echomax Active X S is the way to go, and AIS receiver unless your are using the AIS B to track your higher fleet or training boats etc, where 15mins delay is not an issue

15mins at 30 knots you can be a fair distance !

[willk]

There's a 15min delay on AIS B? Do you mean websites that reuse that data?

[SPR]

Originally Posted by willk

There's a 15min delay on AIS B? Do you mean websites that reuse that data?

Doh! slaps head in homer simpson style!

why did I think AIS B was 15 mins delay (-prob because I been selling SPOT 2 messengers today, that up dates there tracking every 15 mins when in tracking mode!)

AIS B is every 30 seconds By default , at 2 watt
AIS A is every few seconds and at 12 watt

S.

PS. RYA Article AIS transmissions from small craft | Current Issues | Cruising | RYA

Automatic Identification System - Wikipedia, the free encyclopedia

[Channel Ribs]

The RYA article concludes that AIS B is not a single cure for all, they recommend that it be used as part of a balanced diet.

[Polwart]

Originally Posted by Erin

I had to read the article a couple of times to try and understand it. In one paragraph it stated that no manufacturer produces a unit that can filter out the signals and then in the next breath says that units can be set to filter.

I would have thought that there would be risk of negligence aimed at any captain who decides to filter out the signal if it results in a collision. I also don't see where the logic of clutter comes in either. Surely the time when there is 'clutter' is the busiest and most risky for collison and they would want all info available on other vessels tracks that they can get.

Yes I can't understand why a ship would want to turn off this unless there was so much "clutter" that it was obscuring other relevant info (like the other big ship ahead). That situation can really only be a problem in places like the solent (where its likely that a large vessel is constrained to the channel and "class b" boats would have to give way anyway). I'm not sure what the RYA is getting its knickers in a knot about: even without the ability to hide class B boats there is no guarantee that the bridge crew will identify and respond to any impending collision anyway. AIS transponder may be useful tool but its not human proof at either end, so best to assume you may not have been seen until you see evidence to the contrary. The same applies to Echomax/Seame - it will only help if everything works as intended and then the human beings in the system react correctly - 99% of the time they will but to rely on it is a bit of a gamble.

[Anchorhandler]

Originally Posted by Polwart

Yes I can't understand why a ship would want to turn off this unless there was so much "clutter" that it was obscuring other relevant info (like the other big ship ahead). That situation can really only be a problem in places like the solent (where its likely that a large vessel is constrained to the channel and "class b" boats would have to give way anyway). I'm not sure what the RYA is getting its knickers in a knot about: even without the ability to hide class B boats there is no guarantee that the bridge crew will identify and respond to any impending collision anyway. AIS transponder may be useful tool but its not human proof at either end, so best to assume you may not have been seen until you see evidence to the contrary. The same applies to Echomax/Seame - it will only help if everything works as intended and then the human beings in the system react correctly - 99% of the time they will but to rely on it is a bit of a gamble.

Could'nt have said it better myself...
There are time when i look at our 22" monitor in our office and all i can see is red triangles clogging up the solent. (i will take a screenshot tomorow and post the picture)

There are times when class B AIS is invaluable for leisure boaters but do you really need to have it switch on when your daylight sailing in the Solent or other busy coastal cruising area?...i dont believe so.

Offshore, when near or crossing shipping lanes, night time navigation, fog...yes, switch that baby on... (imagine if the Ouzo could have had AIS fited?) . but a certain degree of restraint should be excersised before that 'on' button is pressed.
I wish yachties would treat their AIR transponders as " a big very bright all-round nav light", fantastic in the right conditions (again, night time, fog etc....) but not in daylight when they are surrounded by hundreds of other yachties all showing the same dazzling all-round light....it just creates confusion for those trying to distinguish one 'light' from another.

Simon

[Polwart]

Simon, what fraction of solent pleasure craft are transmitting? Can you imagine 15yrs time when most might be, as cost falls?

[Anchorhandler]

Originally Posted by Polwart

Simon, what fraction of solent pleasure craft are transmitting? Can you imagine 15yrs time when most might be, as cost falls?

Yep, scary stuff....it definately has the potential of being a victim of its own success.

I would estimate that in the last three years alone the number of pleasure boats transmitting in and around the IOW and Solent must have nearly trippled.

It used to be quite a novel experience spotting a 'leisure' AIS target amongst all the commercial stuff, especially when the said target had an unusual or comical name (a few weeks ago a yacht in Cowes was broadcasting 'Sheik Ya-Bouti' which made us giggle). But nowadays its only really during the week when the ratio of 'commercial to leisure' swings in our favour. On the weekends, its very much a different story!

For us its just a serious inconvenience but for the likes of VTS it can be a real problem.

Its actually quite comical sometimes to 'see' what is in effect virtual 'motorways' on our screen, made up of AIS transmitting yachties all following each other through defined navigational channels (exiting the Hamble river is a prime example)

Simon