I have been too but this gives me pause:
http://www.panbo.com/archives/2008/09/class_b_ais_here_but_worthless.html
http://www.panbo.com/archives/2008/09/class_b_ais_here_but_worthless.html
Waiting for AIS B?
- Thread starter Roger Long
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Maybe my logic is completely wrong, but the way I figure it, if I had AIS, the main purpose would be to monitor other vessels, rather than to inform them of my presence. This is because I would be planning to get out of their way if at all possible, regardless of the rules of the road. Therefore, having an AIS transmitter (vs. just the receiver) wouldn't be that important to me. What do you think of this point of view?
A good day to agree with others
John, I agree with your logic. If all recreational vessels were transmitting, it'd be a bear to keep up with the clutter on the screen. I know where I am, and want to know where other BIG boats are. That said, one day a few years ago when sailing between Pt. Bonita and Mile Rock in "fog so thick" I came up on the buoy at the southwest end of Bonita Channel. Just as I did, a big powerboat came rolling through at 25 knots, no one at the helm, most likely on autopilot. Rather than depending on AIS from rec boats, my conclusion was that buoys are good for waypoints, but don't get too close to them in the fog because there are yahoos out there who are doing the same thing, but not keeping a lookout. I also think the rec boats transmitting on AIS was discussed in Latitude 38 recently.
John, I agree with your logic. If all recreational vessels were transmitting, it'd be a bear to keep up with the clutter on the screen. I know where I am, and want to know where other BIG boats are. That said, one day a few years ago when sailing between Pt. Bonita and Mile Rock in "fog so thick" I came up on the buoy at the southwest end of Bonita Channel. Just as I did, a big powerboat came rolling through at 25 knots, no one at the helm, most likely on autopilot. Rather than depending on AIS from rec boats, my conclusion was that buoys are good for waypoints, but don't get too close to them in the fog because there are yahoos out there who are doing the same thing, but not keeping a lookout. I also think the rec boats transmitting on AIS was discussed in Latitude 38 recently.
"Practical Sailor"
"Practical Sailor" had an article in their November issue on just this question. They point out that "most AIS systems have screen decluttering features that allow users to ignore Class B signals and display only AIS-A transmissions." If larger commercial ships don't use this feature now, they are certain to when class B transmissions become more common. And as for me the main purpose I would use AIS would be to keep track of larger ships, this is one less reason to spend the extra bucks on an AIS-B transponder. There is also the additional draw on the batteries that the transponder would cause.
Its worse than John describes
Most ships are fitted with AIS systems which do not decode certain transmissions from AIS B sets. This means they might, or might not, see the icon from a class B set on their screens and they certainly will not be able to read the 'Static Data' e.g. name of your vessel etc.
Many are using MKD (Minimum Keyboard and Display) because this was the minimum the rules allow and also the cheapest. It was all done in a great rush to comply with IMO regs and before the class B spec was written. This means they even have difficulty in knowing what their own transmissions are like and what information they contain.
Worse still there is no requirement for ships to be upgraded to decode the static data from class B sets during the ship's annual refit.
I have all this from the CEO of the company which makes most of the circuit boards for the AIS set manufacturers.
Most ships are fitted with AIS systems which do not decode certain transmissions from AIS B sets. This means they might, or might not, see the icon from a class B set on their screens and they certainly will not be able to read the 'Static Data' e.g. name of your vessel etc.
Many are using MKD (Minimum Keyboard and Display) because this was the minimum the rules allow and also the cheapest. It was all done in a great rush to comply with IMO regs and before the class B spec was written. This means they even have difficulty in knowing what their own transmissions are like and what information they contain.
Worse still there is no requirement for ships to be upgraded to decode the static data from class B sets during the ship's annual refit.
I have all this from the CEO of the company which makes most of the circuit boards for the AIS set manufacturers.
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