Class B AIS

[Robin]

You're right. Even with new radar systems, in many circumstances Class B transponders won't be seen by ships. Boat owners would get far better value by installing active radar reflectors.

My view is tht I want to be able to 'see' for myself the 'being seen' is less important to me therefore, nice but not essential, and no different from MK1 eyeball used in clear vis. I like the fact that AIS contacts are displayed on my radar/plotter together with alarms etc for detected risks, that data gives me a heads up to start looking harder or to start a radar plot or turn on the MARPA, even to make DSC call on VHF to the other guy. in the ICW over here it is good to have advance info on what is coming up round the corners and to be able to call up and negotiate a passing procedure if needs be.

 

[GHA]

You're right. Even with new radar systems, in many circumstances Class B transponders won't be seen by ships. Boat owners would get far better value by installing active radar reflectors.

"many instances " might depend on where you sail, outside the solent, where around the uk?

http://www.panbo.com/archives/2010/12/class_b_ais_filtering_the_word_from_dr_norris.html

I'd go for strong radar return above ais transmit as well, though.

 

[blampied]

Just a thought
If commercial boats are filtering out class B signals,
what's to stop private boats fitting class A transceivers?
Or is there something in the regulations that forbids class A being used by private boats?
Surly the cost of purchasing the more powerful and expensive class A transceivers due to extra uptake the cost of equipment should be falling like class B?

 

[prv]

what's to stop private boats fitting class A transceivers?

Nothing, and some do. It's more expensive than class B and slightly more complicated to fit as you need a compass input etc, but if you want to you can.

Personally I'd choose an active radar enhancer over either flavour of AIS transmitter though.

Pete

 

[Cardo]

I am always rather curious when I hear about large vessels and/or CG filtering out class B AIS targets. Why? The boats are there, and they should hopefully (though not always the case) be showing up on radar. The boat is there, you might as well have it registering on your instruments. I can understand, for example, CG having different icons for A and B targets, just to differentiate between the big boys and the small'uns. For example, B targets could be a small dot, as opposed to A vessels showing up as triangles, with associated navigation information. But I think they should still have the B targets represented somehow, so they have a clearer picture of what's out there.
Yes, I know the Solent on a sunny weekend is smothered in B targets. That's a good thing. The boats are there, you can't just ignore them. However, maybe the plotter manufacturers need to think of better ways to display the targets? Maybe having the ability to show B targets, again, as small dots instead of large triangles. This way you still see the boats around you, but they don't clutter up the screen. My Raymarine plotter draws the triangles in sizes respective of the size of boat, which is at least a start in the right direction.

As has already been mentioned, I wonder what a court would say if a big ship mowed down a small boat who was transmitting class B, only for the big ship officer to say "Oh, well, there were loads of them about, so we filtered them out..." Surely that's against COLREGS?

I for one will always keep my AIS transmitting when I'm on the go. The higher the chance of being seen, the better.

 

[Mrnotming]

It must be tempting to have a SART near to hand to activate in extremis?
Or have these been banned by now?Puts a series of lines radiating from your position on all receiving radars?
Don't all rush out to buy together,or we are back in square one!
Good thread,keeping those of us with only a monochrome radar up to date!

 

[Sandy]

In that case, a simple AIS receiver will suffice - no need for a transponder.

Depends how you want to use it.

Seeing who is about is one thing, especially in busy areas but letting other boats know you are about is also fun.

We don't have AIS onboard, that is planned for the next boat, but we sail in quiet waters and the big boys tend to leave us well alone - unless we are hopping over to France.

 

[Colvic Watson]

Seeing who is about is one thing, especially in busy areas but letting other boats know you are about is also fun.

Having sneered at class B signals I now confess to a guilty pleasure at seeing us on Boatbeacon, we may not be showing up on any ships but the yachts out there can see us.

 

[Sandy]

Having sneered at class B signals I now confess to a guilty pleasure at seeing us on Boatbeacon, we may not be showing up on any ships but the yachts out there can see us.

Are you sure?

Reading the web page

With transmit enabled your boat will appear on other Boat Beacon devices. If you enable AIS sharing and have an MMSI number your boat will also appear on live AIS traffic sites and their associated mobile applications

I don't think it is a true AIS transponder. Ideal for letting family know where you are as they can see you on the web.

 

[Colvic Watson]

Are you sure?

Reading the web page


I don't think it is a true AIS transponder. Ideal for letting family know where you are as they can see you on the web.

We have an actual class B transponder, and it shows up on Boatbeacon.

 

[Robin]

I am always rather curious when I hear about large vessels and/or CG filtering out class B AIS targets. Why? The boats are there, and they should hopefully (though not always the case) be showing up on radar. The boat is there, you might as well have it registering on your instruments. I can understand, for example, CG having different icons for A and B targets, just to differentiate between the big boys and the small'uns. For example, B targets could be a small dot, as opposed to A vessels showing up as triangles, with associated navigation information. But I think they should still have the B targets represented somehow, so they have a clearer picture of what's out there.
Yes, I know the Solent on a sunny weekend is smothered in B targets. That's a good thing. The boats are there, you can't just ignore them. However, maybe the plotter manufacturers need to think of better ways to display the targets? Maybe having the ability to show B targets, again, as small dots instead of large triangles. This way you still see the boats around you, but they don't clutter up the screen. My Raymarine plotter draws the triangles in sizes respective of the size of boat, which is at least a start in the right direction.

As has already been mentioned, I wonder what a court would say if a big ship mowed down a small boat who was transmitting class B, only for the big ship officer to say "Oh, well, there were loads of them about, so we filtered them out..." Surely that's against COLREGS?

I for one will always keep my AIS transmitting when I'm on the go. The higher the chance of being seen, the better.

Don't sail in known pirate waters then or where drug smugglers are known to sometimes hijack cruising yachts to use for their nefarious purposes.:disgust:

OUrs will be transmitting under all normal circumstances but I reserve the ability/right to switch it off when commonsense suggests, which if we still sailed in crowded Solent waters, Which we do not, includes there.

 

[BrianH]

I don't think it is a true AIS transponder. Ideal for letting family know where you are as they can see you on the web.

I've sailed the Adriatic Sea with an AIS receiver only now for seven years and it has been a boon, especially helping me to avoid the high-speed ferries that heavily populate those waters and seem to have little regard for colregs. It has also helped to inform me when to duck through the convoys of ships that seem to exit the Gulf of Trieste in line and when to cross the TSS there.

But the receiver was an early model and non-parallel channel - switching alternately between the two channels and often being out of synchronisation with the static data messages, leaving me too long without ship's name to shout at on VHF when about to be run down. So I've now got a modern, simultaneously parallel receiver plus a transponder ... the latter not so much to be seen by others but to allow my home-bound wife to be reassured that I am still afloat by means of MarineTraffic. http://www.marinetraffic.com/

This is an excellent, free service with efficient receive stations in my area (especially #44 in Slovenia) - well able to provide real-time target reports - even for the 2W Class B transmissions - over the entire northern Adriatic.

 

[Cardo]

Don't sail in known pirate waters then or where drug smugglers are known to sometimes hijack cruising yachts to use for their nefarious purposes.:disgust:

OUrs will be transmitting under all normal circumstances but I reserve the ability/right to switch it off when commonsense suggests, which if we still sailed in crowded Solent waters, Which we do not, includes there.

lol, ok, there may be times when I'll turn off transmit due to circumstances (though I don't plan to sail in pirate infested waters!).
However, crowded Solent waters is not a time when I would turn it off. I'm still taking up that patch of water, so I'll transmit to inform others, in case their Mark 1 eyeballs are faulty.

 

[BobE]

AIS Transponers etc CLASS B

Read the thread so far interesting....
I have an out of date Raymarine Radar with MARPA which allows me to plot upto 10 targets and tells me their CPA's etc.
I also have an out of date Std Horizon Chart plotter and a Nasa AIS box which shows up the class A targets/vessels. (Everything's becoming out of date!)

However I cannot see Class B on the screen altho' NASA have updated their chip.
Don't want to change the plotter ('cause it's movable and I can have it at various locations) and Std Horiz say their chip cannot be updated.
2 years ago whilst in company with a Class B fitted boat, he was warned by a towing tug, and passed the warning on to me. Which was nice but I'd already eyeballed the tug and didn't need to chat to him on VHF. However it temps me to have a new toy!

I believe that there is a significant time lag with the AIS system, I've certainly eyeballed large vessels crossing my bow and see them still approaching on the AIS shown on the plotter.

This of course doesn't occur with the Marpa Radar it's all controlled by my unit...

Wonder about Boat Beacon, played around with it.... Sucks the Samsung phone power, and does it work offshore ?? I haven't had a chance to try it at sea.

Anyway which class B transponder/receiver units do you recommend? 'Cause I'm still tempted to let her see when I'm going to be home!
Or maybe that could be a mistake?
Cheers Bob E

 

[GHA]

I believe that there is a significant time lag with the AIS system, I've certainly eyeballed large vessels crossing my bow and see them still approaching on the AIS shown on the plotter.

This of course doesn't occur with the Marpa Radar it's all controlled by my unit...

Something sounds wrong there, depending on vessil speed class a should be transmitting somewhere between 2 and 10 seconds from memory. Are you sure the tide wasn't setting the boat?

 

[Twister_Ken]

lol, ok, there may be times when I'll turn off transmit due to circumstances (though I don't plan to sail in pirate infested waters!).
However, crowded Solent waters is not a time when I would turn it off. I'm still taking up that patch of water, so I'll transmit to inform others, in case their Mark 1 eyeballs are faulty.

We're diametrically opposed. A Class B transceiver is going into my noble vessel shortly. In the Solent (except in rotten viz) it will remain off - as indeed my AIS receiver has for the last three years*. In the 40 something years I've sailed in the Solent, shipping/yacht accidents have been mercifully rare, without any AIS operating. My belief - AIS is unnecessary in the Solent, and may even be counter-productive. If a surfeit of Class B transmissions swamp the heavy metals' receivers, then Class B will be ignored, to the detriment of those misguided fools who are relying on it for detection. As for AIS performing better than eyeball in crowded waters, I'm totally unconvinced.

My AIS will only transmit beyond Bem Ledge or the Needles Light - except, as said, when visibility is poor.

*The reason it's off?
a) I don't want the alarm going off continuously because I'm close to transmitting yachts.
b) in good viz I prefer to look around me, rather than stare at a screen.
c) if there's a ship out there, I can see it.

 

[AntarcticPilot]

Nothing, and some do. It's more expensive than class B and slightly more complicated to fit as you need a compass input etc, but if you want to you can.

Personally I'd choose an active radar enhancer over either flavour of AIS transmitter though.

Pete

There was a discussion of this on the Ships forum (http://www.ybw.com/forums/showthread.php?260110-AIS-Question), and the regulations (AFAIR) state that a class A installation has to be properly certified; you can't just buy the kit and fit it. The opinion on the forum (from big ship people) was also that a fluxgate compass wouldn't cut the mustard; it would need a gyro.

One reason for the slow rate of adoption of new technology by shipping is the requirement for equipment and installations to be certficated by class societies etc.; this is costly and slow, so it takes a long time for new technology to make it onto bridges, and of course, only those already supplying bridge equipment are going to carry out the certification. It isn't just the inertia caused by unwillingness to spend money! The kit we have available as leisure sailors is probably more technically advanced that that available to commercial shipping. Less powerful, but within the limits of power and space, more advanced.

 

[Tidewaiter2]

I just wish Class B transponders owners would switch the F@££$% things off when moored up- one in Bembridge again this weekend-' Dangerous Target', My A@@@@, at dead LW!
Cowes marinas are a nightmare!
it's like 'Amateur Night at the OK Corral'.:dejection:

 

[Robin]

I just wish Class B transponders owners would switch the F@££$% things off when moored up- one in Bembridge again this weekend-' Dangerous Target', My A@@@@, at dead LW!
Cowes marinas are a nightmare!
it's like 'Amateur Night at the OK Corral'.:dejection:

Ours goes off when the plotter is turned off or if forgotten when the batteries are switched off, but we can turn off the transmissin of data with thereceiver on if we wish. It will always be off when we leave the boat. I haveeve seen fast movib=ng targets on I-95 the interstate highway, presumably trailered boats with sets still 'on. we have 6 'CPA warnings from boats in our marina too.

 

[Giblets]

I just wish Class B transponders owners would switch the F@££$% things off when moored up- one in Bembridge again this weekend-' Dangerous Target', My A@@@@, at dead LW!
Cowes marinas are a nightmare!
it's like 'Amateur Night at the OK Corral'.:dejection:

"Fay's Fantasy" has been transmitting continuously for at least the last four years from Port Solent. Never, ever seen it move from there!