AIS Question

[donradcliffe]

I think I pretty well understand what was going on with Jesssica that night, but am much more concerned with what was happening on the bridge of the chinese ship. The preliminary report states that they saw a green light about 4 miles out, and tried to change course at the last minute. The first statement seems a bit incredulous, as Jessica's light range would be more likely 2 miles unless you knew where to look with binoculars. The second statement is consistent with Colregs if you are the stand on vessel, which they would have been if Jessica had been under power.

I think that were sone language difficulties in the preliminary report, and the litigious nature of the Aussies may stifle gettting at the real story, but I would love to know what really went on--what did the ship's AIS and radar tell them, and what did they think the situation was at the time.

Another interesting point was that the Australian shore-based AIS receiver was tracking both boats. Was that station part of VTS, or separate. It seems to me that with a bit of programming, a VTS AIS computer could provide warnings of collisions with other vessels or fixed objects. It wouldn't work in crowded Sydney harbor, but it might be quite useful for coastal areas in the wee hours of the morning.

[btrayfors]

The would have been the give-way vessel, no matter if she were under sail or under power, unless they were in a narrow channel which I don't think applies here.

I agree with your concern about the ship, though. What action did they take, if any?

And, when they did turn, they turned the WRONG WAY, according to good practice and the COLREGs. Further, if they had been monitoring her correctly, they could have stood on the same course and missed her, leading to the possibilities that: (a) they weren't monitoring that closely; (b) they read the data wrong; (c) the turn had nothing to do with her; (d) the turn was a last-minute panic action -- and an incorrect one; or (e) something else or some combination of the above.

B.

[Lodesman]

Originally Posted by btrayfors

The would have been the give-way vessel, no matter if she were under sail or under power, unless they were in a narrow channel which I don't think applies here.

I agree with your concern about the ship, though. What action did they take, if any?

And, when they did turn, they turned the WRONG WAY, according to good practice and the COLREGs. Further, if they had been monitoring her correctly, they could have stood on the same course and missed her, leading to the possibilities that: (a) they weren't monitoring that closely; (b) they read the data wrong; (c) the turn had nothing to do with her; (d) the turn was a last-minute panic action -- and an incorrect one; or (e) something else or some combination of the above.

B.

According to the ATSB report, the Silver Yang was on a northerly course and Ella's Pink Lady was off her port bow on a south-easterly course. If EPL was under power (I'm not saying it was, just if) then she would have been the give-way vessel. The crossing rule isn't backwards in the southern hemisphere.
The report also indicated that SY altered to starboard, but EPL altered to port in the moments before the collision. SY's alteration was insufficient, but they did go the right way according to Colregs and good practice.

[btrayfors]

Absolutely right re: the give-way vessel. Sorry; guess I'm turned around upside down thinking about all that toilet water running the wrong way down there :-)

My apologies.

Bill

[highseas]

Its nice to know that the ships carrying speeds of more than 20 knots are sending AIS to my receiver,as those are the ones that come up out of nowhere.It gives me plenty of time to take action to avoid being runover.I have picked up targets as far as 128 miles away on open ocean on a smooth day.Every bit of info. helps out there.

[Bash]

For years cruisers have been complaining about ships not responding to VHF hails. In my experience, a ship is far more likely to return a hail if it is called by name. If nothing else, AIS gives you the ability to do that.

BTW, I've had a USN warship contact me at night and request a course change. Not only was it running without broadcasting AIS, but it was running without lights.

[Zanshin]

Bash - with AIS and DSC it is even more likely, since if you use the other ship's MMSI to initiate a DSC call it will be logged in the recipient's radio and cannot be purged from it. I don't know the specific rules, but think that any ship required to have AIS must also carry DSC comms and, if carried, it must be monitored.

[goboatingnow]

yes carriage requirements for ships require DSC VHF ( and DSC SSB)