Assessing the risk of collision.

SimonCr

Either
1. use AIS to get the name/callsign from your radar position of them.
Or
2. Call the ship at position (to the nearest mile only) and speak clearly and don't just blurt out the position. Say something first that distinguishes the ship. "Loaded tanker heading west at ..." "Blue sided container ship turning to port at ..." "Panamax heading south at ..." That gives them a chance to tune into your accent.

A lot of ship names are impossible to say correctly. And yacht names are equally as bad, so use the yacht callsign initially as non English speakers can only answer if they know who called. Again clearly as they do not all use the same alphabet. Even if they get it wrong you know it is you they are calling. I found we have many more replies if the initial call did not involve the word yacht and just had a callsign but no name.

If the position estimate, to a mile accuracy, could be confused then describe the boat direction. If a mile accuracy involves more than 2 ships you probably are in a channel and your the one that should be getting out of the way.

If the radio that responds is of dubious nature then ask them to confirm a feature of their ship in day light. Colour, number of cranes, cargo type. Don't ask a question that requires a yes or no. Or at night, confirm they see your beam light.

Off Gib in 1998 a dingy identified a ship by setting fire to their clothing! But that is an extreme!

You can tell when there are language difficulties quite easily. I have never had a confusion over ships. Also giving their position only means they have to listen while looking at the GPS. It used to be common practice for the ship to respond with their position and name for confirmation. We normally run with Radar off and as long as you start early the 90 second warm up is no problem.

Off India, after Iraq we did get a few problems. "If you want help ask Mr. Bush!" was one reply. But then they were tankers.
 
Shmoo:

Nice example of AIS. thanks. However, that is a place I would NOT be calling a ship. There is no way that a yacht should be talking with a ship in those confined waters.

The trick I use (works in the channel) is to use the buoys. If you can not cross at the narrow point then just cross to the buoy and hide behind it until its good to go again. In Singapore there were 8 boats (locals and yachts) waiting to "cross the road" by the time a space appeared.
 
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However, that is a place I would NOT be calling a ship. There is no way that a yacht should be talking with a ship in those confined waters.


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No, no, no of course not. It was just an image I had to hand. By the way I made it into a link becuase it was too big for the page.
 
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How do you know that the ship that is answering is the one that you've seen, and that the yacht that they've seen is you and not someone else?

[/ QUOTE ]I suspect that people will argue quite reasonably that by using AIS you know the name of the ship.


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Unless I am missing something here: I select "measure"; put the cursor on icon for MV Nonsuch on the chart display; drag it to the boat icon in the middle of the screen (me) and read off the distance and bearing. I don't need radar to do that (I may need it for lots of other things but that is a different issue)

[/ QUOTE ]This is where you have the advantage over me. I have read the articles, played with one in the flesh, but we don’t have AIS at the moment and I had forgotten that they have that feature. I assume that you have to give the reciprocal of the bearing that is given?

It still doesn’t alter my feelings about VHF and how often it confuses the situation, but I can see how we might get to a point where it might help sometimes.

However even knowing the name of the ship - and I've sometimes managed to read the name through binculars and been able to give a good lat/long of their position with a course and speed from my radar, VHF often adds to the confusion rather than makes things clearer. I therefore still stand by my feelings on VHF use and collision avoidance. For many people using the VHF can lead to a false sense of security and takes your eyes off what is really going on around you.
 
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I assume that you have to give the reciprocal of the bearing that is given?


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AIS puts the ship icons on the plotter software display. Then its the plotter software that gives you range and bearing between any two points on the display as one of its basic funtions. You can start from either end, as it were: put the cursor first on the threat then pull it to the boat, or the other way round.

I agree VHF needs to be used carefully. The real answer is to employ all the tools on offer to build up a complete picture of the situation and then be an active player in it.
 
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For those of us still using paper charts, AIS doesn't offer much does it?

[/ QUOTE ]You got there first!

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Before we had our present Raymarine radar/plotter/AIS setup, we had a NASA 'AIS Radar'. It gave us approximate range and bearing, together with relative course, MMSI and ship's name. Quite enough to establish risk of collision and to allow VHF contact (if necessary, which it never was) without the use of a plotter.
 
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Another confession then: I suppose it would help if we had a plotter! How quaint and old fashioned are paper charts and a GPS... We do have a nice radar though.

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I often wonder how we managed before we had radar, plotters, and GPS, but we did. I dont know if there were more incidents then, but I dont think so.

The thing is that new things come along and we learn how to use them, gain confidence in them, and they become the norm, generally making life easier and safer. There are places I can go now that I would never have dreamed of 20 years ago. If one plotter were to fail, the backup PC plotter does the job.... the chances of both failing are slim, and battery backup is available if the electricity supply failed.

It wouldnt surprise me if AIS and VHF communications become the norm whereas, at the moment, we are justifiably wary of the chances of VHF assisted collisions.

When I sailed on merchant ships in busy waters, (20 years ago), pilots would talk to each other about their actions and things worked OK because they knew each other, knew which boats they were on, and where they all were.

The problem with VHF assisted collisions was that the 2 boats communicating though each was a different boat. AIS and the extra information it provides "should" remove the ambiguity.
 
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Another confession then: I suppose it would help if we had a plotter! How quaint and old fashioned are paper charts and a GPS... We do have a nice radar though.


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(sorry about delay: been to bed!)

Yes a plotter does display the AIS stuff in context. Having said that, and to kill the paper charts/plotter hare before it runs, we have paper charts for everywhere we sail and we plot hourly positions on them on passage.

Indeed you have to have the paper charts with Seaclear plotter software becuase it runs on scanned in (and calibrated) charts.
 
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Before we had our present Raymarine radar/plotter/AIS setup, we had a NASA 'AIS Radar'. It gave us approximate range and bearing, together with relative course, MMSI and ship's name.

[/ QUOTE ] Thank you for the suggestion. Electronic charts don't appear anywhere on Freestyle's capital program, the first 10 years of which will be taken up with essentials such as decent ground tackle, and the replacement of ageing equipment such as number the genoa, the furling gear, the 19 year-old radar, etc. A radar display that shows AIS data would be a real boon.
 
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A radar display that shows AIS data would be a real boon.

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Careful. The NASA "AIS Radar" is not a real radar. It's an AIS receiver with a radar-like display. Its biggest handicap (to my mind) is that it's always north-up, and has no heading marker, so that you have to mentally put in a heading marker before you can work out where to look. Plus, of course, that it only shows vessels that are transmitting AIS signals. Nevertheless, it is a very useful addition to the armoury.

PS If you are thinking of replacing the radar, many modern radar sets can display AIS signals.
 
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many modern radar sets can display AIS signals

[/ QUOTE ] Definition of a technophobe: someone who elects to quit fiddling with gizmos until the grandchildren are old enough to explain them.

(Definition of an alcoholic: someone who drinks more than their doctor.)
 
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