How much use is AIS
- Thread starter sailorman
- Start date
Barnacle Bill
Active member
It looks exactly like a 'radar assisted collision' - Ship did the right thing, fishing boat became confused by his own alterations of course. Page 40 of Essential Boat Radar describes ...
"Despite the widespread use of radar, vessels continue to collide, and tragically there have been instances where two vessels equipped with radar have managed to engineer a collision which would never have happened without it. A typical scenario is as follows:
• Ship A, heading due north, observes a target fine on the starboard bow, at relatively long range. Because of the range, the bearing changes very slowly, so the skipper decides that the other ship is heading south and will pass down his starboard side, but rather too close. He alters course 5 degrees to port, and instantly the radar picture becomes much more encouraging, because the target is a lot further away from the ship’s heading line.
• Ship B, the target vessel, was in fact heading slightly west of south, and therefore observes Ship A fine on his port bow. For similar reasons to Ship A, his instinct is to “turn away” from the target and he alters course to starboard.
• Gradually, both skippers notice the target vessel getting closer to their heading line again, so they each repeat their previous course alteration.
• This process continues until they collide!
Having personally made a similar mistake, but fortunately with a happier ending (we were unable to catch up with the ship to collide with it!) I am very aware of how confusing this kind of situation can be. Your own course alterations make it far harder to work out what is going on. The answer is to observe the other vessel for longer without making any course alterations, and not make assumptions about what it is doing, particularly at long range when you simply don’t have enough information."
"Despite the widespread use of radar, vessels continue to collide, and tragically there have been instances where two vessels equipped with radar have managed to engineer a collision which would never have happened without it. A typical scenario is as follows:
• Ship A, heading due north, observes a target fine on the starboard bow, at relatively long range. Because of the range, the bearing changes very slowly, so the skipper decides that the other ship is heading south and will pass down his starboard side, but rather too close. He alters course 5 degrees to port, and instantly the radar picture becomes much more encouraging, because the target is a lot further away from the ship’s heading line.
• Ship B, the target vessel, was in fact heading slightly west of south, and therefore observes Ship A fine on his port bow. For similar reasons to Ship A, his instinct is to “turn away” from the target and he alters course to starboard.
• Gradually, both skippers notice the target vessel getting closer to their heading line again, so they each repeat their previous course alteration.
• This process continues until they collide!
Having personally made a similar mistake, but fortunately with a happier ending (we were unable to catch up with the ship to collide with it!) I am very aware of how confusing this kind of situation can be. Your own course alterations make it far harder to work out what is going on. The answer is to observe the other vessel for longer without making any course alterations, and not make assumptions about what it is doing, particularly at long range when you simply don’t have enough information."
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GHA
Well-known member
2nd time up, though might get a discussion going this time.
Very sad.
http://www.ybw.com/forums/showthread.php?392105-Mar-de-marin-baltic-breeze-collision
Very sad.
http://www.ybw.com/forums/showthread.php?392105-Mar-de-marin-baltic-breeze-collision
Tony Cross
Well-known member
To avoid the collision the fishing boat turned to port. Mistake.
john_morris_uk
Well-known member
Not sure what discussion there is to have.
AIS, Radar, reduced visibility or not, the fishing boat shouldn't have turned to port. It's specifically mentioned in IRPCS for good reasons.
AIS, Radar, reduced visibility or not, the fishing boat shouldn't have turned to port. It's specifically mentioned in IRPCS for good reasons.
Just_sayin'
Well-known member
Agreed.
Presumably it's ok for Sailorman to not scour each post before posting, unlike his unnecessary observation here
http://www.ybw.com/forums/showthread.php?389361-How-not-to-enter-harbour
Barnacle Bill
Active member
Clear what the mistake was - question is, why did he do it?
One possibility is he made an early incorrect decision that they were going to pass starboard to starboard, and became confused by the radar picture caused by his own course alterations.
Another was that he was drunk. Who knows ...
sailorman
Well-known member
GHA
Well-known member
Of course, worth getting a a discussion going, though maybe not much to discuss,...... turn right.
Just_sayin'
Well-known member
you have a nice day
Enjoying myself immensely thanks.
sailorman
Well-known member
me, awaiting tide & travel hoist for haul-out
KellysEye
Active member
>How much use is AIS
We never used it seemed pointless, and a waste of money, when someone is always on watch using the Mark One eyeball.
We never used it seemed pointless, and a waste of money, when someone is always on watch using the Mark One eyeball.
capnsensible
Well-known member
Are there special eyeballs you can get for use in busy areas when the visibility is poor or its raining? Are they cheaper than AIS?
Borden
New member
In poor vis I've found AIS to be very useful in 'seeing' shipping that I an unable to see visually. 70 miles off the E coast of Italy three years ago in a F7 at night with big swells plus thunder storm rain vis was very poor but AIS was telling me what was about and where they were heading . The area was busy with shipping heading down the Adriatic. Having a picture of surrounding shipping was invaluable as we were trying to stay on a close/beam reach for safety which was made difficult by the sea state so it was important to have advance knowledge of traffic around us. We also have radar but there was so much clutter the AIS plot was giving a much better picture.
I would add that for the majority of our cruising AIS is not switched on (we only receive), but on long offshore passages I wouldn't be without it. Given the minimal cost I consider it a safety aid that I wouldn't want to be without.
I would add that for the majority of our cruising AIS is not switched on (we only receive), but on long offshore passages I wouldn't be without it. Given the minimal cost I consider it a safety aid that I wouldn't want to be without.
prv
Well-known member
Translation: "I have no experience of it, and therefore little basis on which to give advice."
Pete
Pinnacle
Well-known member
+1
Tony Cross
Well-known member
For me AIS (receiving) is invaluable when I'm in shipping lanes out here. Without it I spend a huge amount of time watching that big ship that's just come up over the horizon trying to determine how close it will get to us. With AIS it's relatively simple. That doesn't mean I don't keep watching it of course, but it does mean I have a far better idea of whether he'll pass ahead or astern of me and how close he'll be. That way I can make better choices on what to do early on.
john_morris_uk
Well-known member
We will never know as unfortunately (my understanding) is that the fishermen all died.
sailorman
Well-known member
these 2 ships both had ais but the fishing vessel turned to port into the path of the car carrier that had already taken avoiding action by a turn the stbd
john_morris_uk
Well-known member
I'm normally fairly sanguine about these things but I wonder if the fishing boat ought to have been named 'Deathwish'?
