Use DSC position request to alert shipping

[Ric]

That might be because they've seen you on their radar.

More likely because they've seen me on their AIS. I say that because it has been very noticeable this summer how fewer close encounters I have had compared to previous seasons when I have not had active AIS.

Also, I know my AIS gets picked up by shore stations at about 30m because I have seen myself on AIS websites that far off-shore. I know the French coastguard can see me at at least 80nm because I asked Toulon for an AIS check when on my way to Menorca this summer. Given that a ships radar is probably about the same height as their AIS antenna, it is also more probable that they will receive a signal from the AIS antenna on the top of my mast (even at a measly 2w) than the tiny reflection that they would get from their radar.

 

[oldvarnish]

More likely because they've seen me on their AIS.

It's quite possible, of course. I have noticed that since I fitted a radar transponder ( Echomax) that I get a sense that ships might be altering course having seen me sooner - but it's only a sense. I can't prove it.

It is very easy to draw a false conclusion on the basis of anecdotal evidence. For example, a ship might not be altering course for you or me, but for another vessel of which we have no knowledge and cannot see.

The most reliable option is always to keep your eyes open and get out of their way - apart from in fog when you've got to take your chances.

The other assumption you make is that as much attention is given to an AIS plot as to a radar screen. It would be interesting to hear from someone with bridge experience who could tell us if that is the case.

 

[Ric]

It's quite possible, of course. I have noticed that since I fitted a radar transponder ( Echomax) that I get a sense that ships might be altering course having seen me sooner - but it's only a sense. I can't prove it.

It is very easy to draw a false conclusion on the basis of anecdotal evidence. For example, a ship might not be altering course for you or me, but for another vessel of which we have no knowledge and cannot see.

The most reliable option is always to keep your eyes open and get out of their way - apart from in fog when you've got to take your chances.

The other assumption you make is that as much attention is given to an AIS plot as to a radar screen. It would be interesting to hear from someone with bridge experience who could tell us if that is the case.

Suggest you read the thread referred to earlier on gcaptain.

 

[prv]

The other assumption you make is that as much attention is given to an AIS plot as to a radar screen. It would be interesting to hear from someone with bridge experience who could tell us if that is the case.

Depends largely on the installed kit. ECDIS (ie, big-ship chartplotter) will combine chart, radar and AIS for a single unified view. Less up-to-date ships may well still be running on paper charts, standalone radar, and a small (and ignored) AIS screen with three small lines of text. I've spent many hours (though not as OOW) on the latter variety of bridge.

Pete

 

[oldvarnish]

Suggest you read the thread referred to earlier on gcaptain.

Yes, I had a look at that.

My broad point is this. An AIS receiver is one of the best safety devices we've had since GPS. It removes all the uncertainty from collision situations with big ships and saves us all those sweaty minutes with a hand-bearing compass trying to decide what might or might not hit us.

What I fear is that people are fitting AIS transponders in the belief that they now have the undivided attention of the watch officer on the bridge of a large ship, and so they can relax.

I don't believe that to be the case. That's all I'm saying.