AIS vessel accuracy looks to be getting USCG attn

[continuouswave]

Originally Posted by bobgarrett

...Remember, this denotes vessel TYPE not what the vessel is currently doing. This is set out here on page 11 http://www.imo.org/en/OurWork/Safety...uments/227.pdf...

Thanks for the pointer to that very informative document. I had not seen that before.

[ronstory]

Yes, and section 5 of the IMO spec seems to be the section where most programing mistakes occur. Also, below is the URL for the ITU doc that it references:

https://www.itu.int/dms_pubrec/itu-r...8-S!!PDF-E.pdf

[roland stockham]

Originally Posted by Jim Cate

Roland, are you saying that you have a class A AIS on your 35 foot yacht?

Pretty unusual!

Jim

Not it's class B Opps no I don't set destination just change from anchor to underway

[roland stockham]

I am not sure why it was set this way but the distinction between pleasure and sail would give fair indication of top speed and they know you may be the stand on vessel if you are a sailboat

[Dsanduril]

Originally Posted by roland stockham

Not it's class B Opps no I don't set destination just change from anchor to underway

Class B doesn't transmit operational status (underway, anchored, moored, fishing). On our Class B the only thing that changing status does is adjust the alarms - collision alarms don't sound when using 'anchored' profile, but do with 'underway'.

FWIW I've had any number of class A transponders steam by me at full speed showing 'anchored' status, the human entered data is indeed pretty suspect.

[roland stockham]

Well you learn something every day. I always assumed that the transmission changed when you changed from anchor profile to one of the underway ones. As others say I rarely pay attention to anything other than position course and speed. Actually it is a while since I did much with it as I have been around the Panama canal where there are so many targets it was swamped an them moved N where there is nothing!

[clownfishsydney]

Class A need to have destination and status changed manually. I volunteer for Marine Rescue NSW and I know that our boat skippers often forget to change this information, so it may say "at anchor" when motoring and so on. A good reason not to have Class A on small boats.

[tanglewood]

Having incorrect Voyage data on a Class A is really just a minor annoyance, in my opinion. I change mine between anchored/moored/underway pretty reliably, but not always. And I always leave the Destination and ETA blank.

But I really don't think there is any excuse for the static programmed data to be incorrect, and I think that's the real issue. Incorrect boat size, type, call sign, boat name, and MMSI I think are more significant issues if they are wrong. And they only need to be programmed once when the AIS is installed, so you can't blame it on operator error or laziness like the things I admittedly do.

I always though the US rule requiring the selling dealer to program the static data was a bit silly, but apparently not. With all due respect to my Canadian friends, it's clear that end-users cannot be relied on to correctly set these devices up based on all the incorrectly programmed Canadian boats that I see.

And a new, even worse problem is emerging now that AIS equipped boats are getting sold. The new owners are not reprogramming them to reflect their new names, etc. So all sorts of boats are parading around announcing themselves as some other boat. Both of my last two boats are still broadcasting my original info. When I sell my current boat, I will clear everything before I transfer it.

[Pelagic]

I think one of the dangers when you "dumb down" collision avoidance with a tool like AIS, is that those "dumber" skippers tend to blindly rely on it.

When glitches occur with the equipment... be it technical or operator induced, they lack the training and methodology to independantly verify the data and become fully aware of this error.

I have AIS because it is now mandated in certain areas, but radar plotting from 12 to 3nm then eyeball at closer ranges still remains my primary tools in Asia with AIS as a handy identifier, but not a reliable electronics aid to collision avoidance