I must confess I am a gadget-man, and, having sailed for more than 50 years, I purchased an Raymarine C80 Multi Function Plotter Display together with an AIS Receiver/Multiplexe BRSR at the London boat show this year and find them the best purchases I have ever made.

I used my Radar and AIS and overlaid them onto my Raymarine C80 screen during a period of fog which was never more than 150 yards for more than 21 miles on two occassions during my last cruise and found the AIS was MUCH more valuable than the radar. Besides providing me with ALL the details of vesals within range (and there were many) their bearings and distances were far more accurate.

There are, of course, plus and minuses for all equipment, not least that an AIS is only compulsary for vessals over 300' however, these are the vessals I want to avoid at all costs.

Very satisfied!

George

Hi George

I have found one of the most valuable aspects of the AIS system I have used = NASA engine via a Standard Horizon plotter, has been the CPA = Closest point of approach.   i.e. if your boat and the target continue on that course then the CPA shows you the closest distance you should be from oneanother.  Of course this distance is constantly changing as a yachts heading and course will be a bit erratic in bad conditions, but to continue looking at the screen gives the navigator a really good idea of the closest likely position.

Whilst over 100NM off the Bay of Biscay one night this June, in very unpleasant conditions, we were able to call up two seperate vessels which were within a CPA of 0.2 miles.   One ship had no idea we were there and we had to confirm our position a couple of times to ensure we were eventually well apart. The other only noticed us after another ship alerted him on CH16 and clarrified our position on CH6 in Spanish on our behalf, after our 6 attempts had failed to get a response.  We thanked the intermediary and his response in good English was, "a pleasure sir, enjoy your trip"

Just what we would have done without AIS we are not really sure. We had no clear eyeball contact with these ships over abouta quarter of a mile in the conditions, a bit too close for comfort!    Scotty

Out of interest Scotty did you try DSC calling the ship that didn't answer?

Had similar problem in channel last year while surveying - took DSC call followed by a rather curt reminder as to who was the standon vessel. Heard Dover CG later asking him why he had not responded to our calls - I didn't hear them was the response...

W.

No we didn't Wolfie, but of course if the intermediary hadn't been there then AIS gave us his MMSI No. and this would have been the next option. 

The message here though is it's good to talk and engage with those who are suspiciously on a possible collision course fairly early.  Some of the large ships are travelling at plus or minus 20knots and need time to manouvre if they havn't seen you.

Another friend has just fitted SeaMe which would have helped us to be seen if fitted

.  However, I forgot to say, the intermediary did give the rogue ship our position which had moved on from what we had originally stated so we must have been visible on at least one radar but not possibly all.

When you are so far from anywhere on a black night in big seas, it certainly channels the mind when experiences like this occur!

All praise to the Nicholson 38' circa. 1973 that we were aboard, she was superb!

The other advantage of AIS receivers - at least all the ones I ve used - show course alterations of the target as a rate of turn to port or starboard which also can be a pointer to the fact you ve been seen.

Larger vessel will often make a small course adjustment some distance away rather than a large one when closer. Certain companies have standing orders for the Captain to be called if any course changes are made, so any option to avoid waking a tired grumpy Skipper is probably a better bet!

W.