Serious question Re. AIS

Sixpence

Sixpence

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With all that's being discussed about the Ouzo and AIS , I had a look at movements to the Northern end of this AIS Chart and found an LPG tanker named Monsoon , and its status reads 'Underway by sail'
Is an LPG tanker likely to be under sail ?
Or is this an error ?
Confused of Lincolnshire asking , if this kit is meant to be reliable and isn't , I wouldn't mind a bit of advance notice , could save some expense at least
 
Yes you do get errors with operator input, such as ships at the dockside still showing as steaming but the important bit, the position speed and direction, I assume directly output from the GPS, is in my experience always right.
So much quicker and easier to read the AIS is the best thing since sliced bread when the visibility is poor.
 
Concur - the critical data which is fed in by GPS is generally accurate. The information that requires human intervention - ie Vessel status (underway, at anchor etc), destination and eta are more likely to be wrong...

When it comes down to it - does it matter to you how the tanker is being propelled .... you're not likely to get in it's way are you!
 
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Thank you , that's what I thought , so the system is only as good as the operator , I think I'll stick to the Guapa system

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No - some bits will be picked up automatically from linked equipment, so my guess is that you can have more confidence in the important bits like:

1/ its there
2/ its going in this direction at this speed

What is holds what its name is etc will be a manual input and you cant rely on people.
 
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Thank you , that's what I thought , so the system is only as good as the operator , I think I'll stick to the Guapa system

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No - some bits will be picked up automatically from linked equipment, so my guess is that you can have more confidence in the important bits like:

1/ its there
2/ its going in this direction at this speed

What is holds what its name is etc will be a manual input and you cant rely on people.

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fixed info being course, speed and MMSI number ....... and class A systems will give cpa and time of cpa of each ais

manual input will vary - e.g. draft, destination, eta cargo ........ however the Master is responsible for maintaining the ais correctly, so if the authorities were so inclined they could come down and pay him a visit ..........
 
Confused of Lincolnshire asking , if this kit is meant to be reliable and isn't , I wouldn't mind a bit of advance notice , could save some expense at least
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The equipment is pretty reliable...However it seems there is a lack of discipline on many vessels regarding the input of fixed data.

Frequently you will find ferries indictaing the wrong destination and this morning I see that 50 % of the vessels moored in Aberdeen are showing "underway".

You can t blame the AIS for these errors and one only has to listen to the local VTS radio to hear vessels being pulled up for showing wrong AIS data or non at all.
 
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It can happen on double ended ferries. I think most of the systems automatically switch over but errors can happen.

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COG is either calculated from consecutive position reports or output directly from the GPS receiver as part of the the NMEA RMC message. Either way nothing has to be switched over and it should give the correct track made good whether the ferry is going forward, backwards or sideways.
 
Not necessarily the right conclusion. The operator does not have input to the really important information that is supplied by a dedicated AIS GPS receiver, thus SOG, COG and rate of turn (data required for collision assessment) is as relaible as the ouput of the GPS receiver and not the operator.

Why is it so many people pick up on errors in the least important AIS data output and then say the system is useless when they never seem to bring the important part of the AIS data stream into their argument? From my expereince of using AIS plotting and CPA and TCPA calulations from AIS data alongside radar, AIS is very useful indeed, even in good visability.
 
Okay , let's take your point and put it into a scenario if you like
At the time of posting there were quite a few heavies in that particular area and it was late on a December night , also pretty cold
So let's say I'm on an overnight passage up the coast towards good old Silkie country , I'm freezing cold and approaching a busy shipping area so even without charts I realise I'm likely to be heading into a dreaded TSS
So at night I want to plot a course to get me through to the other side as quickly as possible , I have a scan and note the SOG and COG of all the heavies going in and out along the TSS
I note that they are all steaming at around ten knots , then I find one that is heading out to sea but it's only doing 0.5 knots , which is the speed Monsoon was showing . This surprises me so I have a look and see that it's another fellow hankie boat so no more surprise then , and at that speed I can plot a course across its bows with plenty of time to spare and this fits in with the calculations for getting past all the others safely
So I settle down at the helm with horlicks in hand , knowing that the course I've set should see me through to the other side without spilling a drop , and the skipper of the Monsoon comes onto his bridge and tells the OOW to open her up
No change in COG but she's now going at ten knots and not half a knot . That puts her on a collision course with smug git here as she's now suddenly bearing down on me out of the darkness and my horlicks is going to fly
In this incident (scenario) the boat was indicating that it was a hankie by its speed and description , so if the important stuff is the SOG and COG , there's a good chance I'm going to be treading water if I don't still use the MkI eyeball and genetically enhanced grey matter . I'm more likely to notice lights coming at me faster than expected than I am likely to check the AIS again , methinks
 
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I'm more likely to notice lights coming at me faster than expected than I am likely to check the AIS again , methinks

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thereby hangs the answer ......... you need to keep checking your surroundings by all available means - eyeball, radar and ais.

I keep trying to impress the usefulness of ais is for the yottie ...... for some reason there seems to be a mental blank by some in accepting how ais shows YOU up to him and HIM up (if he is over 300t) to you - along with his IMMS number -so you could immediately alert him ...............

maybe ais isnt covered in enough depth in yoyyie exams, or yottie mags

I know its expensive but it is soooooooo handy - surely worth the price of a weekend away.
 
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