So much for AIS and DSC.

[Jonny_H]

Interestingly we observed the opposite this summer during our cruise (NW England - Wales - Ireland - N Ireland - Scotland - Isle of Man - NW England), we encountered many ships in the Irish Sea and the North Channel who at a distance of say 5 or more miles made an obvious change of course to detour around us and give us a wide (2 mile) berth.

We hypothesised that maybe the Ouzo incident has caused some fear of litigation amongst commercial skippers and they now go above and beyond to avoid yachts.

As I say, this was our experience - don't know if this happens anywhere else - but it was a noticable difference to previous years where they passed much closer or we had to move.

Anyone else experienced this?

Jonny

 

[BlueSkyNick]

[ QUOTE ]


IMHO ship's always have a radar running (saves the watch keeper from having to get out of his chair to look out of the window)..

[/ QUOTE ]

I wouldnt be totally sure about this Oldhand. Friends of ours who crossed the Atlantic on the 2001 ARC saw a ship coming over the horizon towards them, so called on 16 to make sure they had been seen. Watchkeeper responded they would turn on the radar to check. /forums/images/graemlins/blush.gif

 

[Amphitrite]

All Class A AIS units used by merchant ships (or, to be precise, all SOLAS vessels over 300 tons), have an offset for the GPS-antenna of the AIS unit (indeed, the indication of the vessels length is calculated by the distance of the GPS antenna from the bow and stern, same applies for with of the vessel). However, it happens that this is not programmed correctly or that the antenna has been moved...

Regarding bCPA, it is indeed a useful feature of Yacht-AIS - and, as our software was mentioned here (thank you Jonjo), I would like to add that we have introduced calculation for a collision danger area which shows the danger area and makes avoiding action easier (if necessary).
However, I am always happy to receive feedback and wishes here or by PM/email.

 

[ParaHandy]

and hinging the washing out?!!

 

[bilbobaggins]

Re: So much for AIS and DSC.

Wholly agree with Nick and Richard i.r.o. right interpretation, right decision, right outcome. What does concern is the number of other yotties who seek to justify a personal 'gash' approach to these complex problems. I've met quite enough of them....

The ColRegs need quite a lot of work, over an extended period, to gain a sound grasp of what's required of us sufficient to interpret developing situations, decide what the obligations are, and do what's needed, when needed. Some can't be bothered, year after year, and are a hazard to those sailing with them and to the rest of us.

It starts with a woolly understanding of what constitutes 'risk of collision'. This exists whenever two vessels are approaching such that a Line of Constant Bearing exists between them. Now, that risk may be 'imminent', 'soon' or 'later' - depending on distance/time/speed. Its existence, recognised or not, determines that something must be changed, by someone, to resolve the matter - and in accord with the ColRegs.

Rule 7 is the relevant one here, and we are required to use all available means which specifically includes radar....if fitted and operational and equivalent systematic observation - which is, for us, the comparison of a series of observed compass bearings. That's why the Hand Bearing Compass is an essential item of yot safety gear in collision avoidance.

Rule 7 also directs us to avoid making assumptions on the basis of scanty information - especially scanty radar information . It's my view that small craft change course/speed all the time, so that calculated CPAs are liable to significant error and 'safe passing distances' need to be larger, to avoid nasty surprises ( see the Wakhuna/Nedlloyd Vespucci MAIB report )

Once a Risk of Collision exists - or is so deemed - then other rules direct what needs to done and by whom. Rules 8 and 16 make it crystal-clear that required action shall be early and substantial, positive and in ample time.... to be readily apparent to another vessel

I imagine that some here will think that 'Yes, I've read all that and do all that' while many others will simply think 'I can't be bothered with all that guff. I just, sort of, usually, keep out of the way.....' To me, that's an unjustifiable gamble, with high stakes and poor odds.

I'm sure someone will take the view that 'the risk is why I do it' The trouble is, they don't tell their companions in advance, or other water-users, that they've decided to 'play chicken' with ships.....

/forums/images/graemlins/smirk.gif

 

[BrendanS]

Re: So much for AIS and DSC.

I've come to the conclusion, that most seafarers, don't have the intelligence to understand the colregs in full, therefore decide to ignore them, and do their own thing.

 

[Oldhand]

There are always exceptions but at least a ship knows if its radar is working or not whereas it doesn't seem to know if its AIS is working or don't regard it important to check.

Going back to the bCPA discussion, I'm surprised you haven't responded to my suggestion that all you have to do is check the velocity vectors on the AIS display, does Maptech show AIS vectors?

 

[BlueSkyNick]

It shows the vectors of each vessel, to a finite (short) distance ahead. I will need to take a further look to extend them out in the way you previously suggested.

One more thing to add to the 'To Do' list !!

 

[Dann]

I have been plugging for some time for the inclusion of bearing at CPA (bCPA) to be included on the display of an AIS target. Reliance on estimation of a future position using extension of velocity vectors on vessels may be an alternative on some larger PC based screens, but on a small 6 or 8 inch plotter, is, I have found, very hit and miss and could easily lead to the wrong course change being made reducing the CPA further. The extra computation for bCPA should be simple and provide a much more reliable indication of relative future positions, making AIS a much better close quarters avoidance tool !

 

[bilbobaggins]

Re: So much for AIS and DSC.

[ QUOTE ]
"You may very well think so. I couldn't possibly comment...."

[/ QUOTE ]

/forums/images/graemlins/smirk.gif

 

[Oldhand]

Don't know your software but on ShipPlotter you can select the vector length in minutes of time so it shows where all vessels (including your own) will be after the chosen time period, given current SOG/COG. This also means the vector lengths are directly proportional to SOG. I just upscale the chart view if I want to see longer apparent vectors as long as the targets are in range of the scale chosen.