So much for AIS and DSC.

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all have praised their AIS kit where installed (about 30% of yachts I have spoken to).

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Any indication as to which is the most popular/easiest to use/most reliable?
 
[ QUOTE ]
mmm... now you have me wondering.

If I click on a 'target', a task pane opens which gives me all the transmitted info from the vessel, and the calculated tCPA and CPA but definitely not bCPA.

However, there is a seperate task pane option which I have never used, which shows targets within whatever radius is selected. This is the only place I can think where the bCPA might be shown.

Another job for the list /forums/images/graemlins/wink.gif

[/ QUOTE ]

Surely your Maptech AIS plot can display ships course and speed vectors? If you also have a vector displayed for your own vessel, you only have to look and see if the intersection of the vectors, when subtended if necessary, cross. If so the ship is passing ahead, if they don't cross it is passing astern. I certainly find this very easy to discern using ShipPlotter for AIS information and there is no need for bearing to CPA.
 
[ QUOTE ]
Any indication as to which is the most popular/easiest to use/most reliable?

[/ QUOTE ]
NASA and EasyAIS are the two brand names that pop up. I think the display of AIS info has greater influence on the user experiance that the blackbox AIS reciver brain. I like YachtAIS but had to pay for it unlike some other programs. As per this thread I think proportional sized ship icons would be a useful enhancement for close encounters.
 
[ QUOTE ]
on a class a set there is an option to put in the vessels dimensions and position of the ais aerial - yes

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Thanks, so maybe my software already factors this in but until it is improved to show proportional ship icons there will be some close-to guesswork at which point eyeball assessmnt would be preferable.

I will ping the author when I get home, he offers excellent support and phoned me from Germany one evening when I needed a new licence that same day following a laptop Windows Vista re-install.
 
[ QUOTE ]
As per this thread I think proportional sized ship icons would be a useful enhancement for close encounters.

[/ QUOTE ]

ShipPlotter scales ships' sizes from the transmitted dimensions when you go to a big enough chart scale
 
On my new little boat I was going to go for only AIS as a radar would put too much weight aloft. Having had radar I felt that I only really needed it for big ships mid channel at night or low vis. I assumed AIS would give as good a position as radar.

How many ships are out there without AIS transmitters?

Whilst we are on the subject, still can't figure out what to do about radar reflectors as the Ouzo test results seem to suggest that they are all pretty useless....

Overall we all seem to have got ourselves into a real mess. None of the technologies can be relied upon, some ships don't run proper watch systems, not everyone obeys collision regs and ships with tight deadlines insist on doing 25 knots in zero vis. How long before the next Ouzo??
 
Re: So much for AIS and DSC.

Hmm, your choice. I have AIS, radar and mk I eyeball and use all three, in reverse order of reliance.

I'm not sure that we are in real mess, in fog radar finds the ones that will run me down, otherwise mk I eyeball and a reasonable degree of caution/ commonsense have kept me safe over the years.

Regarding the professionalism of commercial crews I can't comment on all of them only my direct experience. I've had the privilege, pre 9/11, of sharing the bridge with a Condor ferry skipper. I was extremely impressed with both the array of detection systems they had on the bridge and their duty of care they displayed when it came to small craft.
 
[ QUOTE ]
How many ships are out there without AIS transmitters?

[/ QUOTE ]
Very few based on 4 Channel crossings this year, there are some wonky heading sensors but these do not upset the COG/CPA calculations.

Since installing AIS I have been impressed by how consistently big ships steer clear, many opt for a nice round CPA figure.

My radar reflector lives in the cockpit locker but I might be prompted to to fly it from a spinnaker halyard given thick fog and a smooth sea.
 
I recently came within a gnat's nadger of being run down by a big ship at night in mid ocean.

There was a huge swell (>6m), wind gusting >40kn, vis was damn all with spray blowing off the waves. We were running under bare poles, the masthead tricolour shook itself to pieces, the bulbs on the lower nav lights then failed within minutes of being switched on when solid water found its way onto the hot bulbs.

This bl**dy great ship appeared and passed within 20 metres. There is absolutely no way they could have known we were there as we had no lights and would have been invisible on radar in that sea. By the time I was called onto deck all I could do was say '[--word removed--]' and look at this block of flats moving away from us.

I could not possibly criticize the person on watch on our boat, In those conditions I don't think anyone would have been able to see the ship approach from behind until the very last minute.

I suppose I should have been transmitting a securite (we did after that!) But we had seen no shipping for a week and saw nothing else for the next week.

We had no radar, but anyway we would have had no power to run a radar. We were not running a plotter as there was no land within 500 miles and we could not waste the power. That is why I want a simple, standalone, low power AIS receiver that could have squawked when the ship was miles away. It's no use to me to require that I am running a radar, or a plotter, or a laptop to use the AIS signal. It would be nice if I could do that as well, but I need low power consumption, mid ocean, ship spotting, and AIS is the nearest. I guess the alternative is a radar detector but I suspect that AIS is easier to use and more reliable.
 
Re: So much for AIS and DSC.

[ QUOTE ]
I was comfortable he was going to pass behind having tracked him for a while.

However, when he is over 8 miles away on radar, one can't work out CPA to any accuracy, h/b compass and eyeball or not.

[/ QUOTE ]

Nick,


On the DSC thing, the chances are that he didnt want to talk, but wanted to shut the thing up - I'm not defending him - he might not have been paying attention for all we know, but we definitely dont know. I guess what I am saying is that this isnt a fault of DSC, except that the annoying bleep is annoying, it's more to do with the user at the other end.

On the AIS - I dont have one, so dont know how it works in detail - it would surprise me if iy gave a CPA, but didnt identify where the CPA was going to be.

You've lost me on one bit - in this post you were happy that he was passing astern but, in another post, because you couldnt see his port side when he was about half a mile away, you gunned the engine because you wanted to resolve the situation and you felt he should have taken some action. I think you did everything right, and the chances are that he did too, although to allow you to get closer than half a mile is cutting it a bit fine - particularly from the point of view of letting you know that he knows, if you see what I mean.

I think I subconsciously make a decision, in each instant, as to how close i need to be to something before a risk of collision is deemed to exist, and it varies. Outside this zone, I am free to do what I like, and I usually try and avoid getting involved with big ships - unless I fancy having a closer look at them - so I do what I think is appropriate to keep out of the way.

I think if you see something at 8 miles, and track it to say 5 miles, and then decide that you will be the stand on vessel, and it has a CPA of 0.4 miles or so, you have a chance to do something to avoid the situation altogether - altering course for his stern is one option which doesnt add a lot to your journey time - whilst it's not recommended, you can then track his stern, (or a bit behind it), so that you remain in control, and dont frighten Mrs Guest SWMBO, he always knows that you are passing astern, and you get to have a look at him.

Cheers

Richard
 
Re: So much for AIS and DSC.

I take your points, maybe I didnt explain myself very well and just bashing this out between worky things !! /forums/images/graemlins/smile.gif

On your last point though, it always seems like a sensible option except that turning to port is a definite No-No, as I understand it.
 
Re: So much for AIS and DSC.

Turning to port is OK as long as its done in PLENTY of time. I've done that when I see a big group of ships coming up on the radar and rather than thread my way throuhgh them I've altered to go behind them all.
 
Re: So much for AIS and DSC.

[ QUOTE ]
On your last point though, it always seems like a sensible option except that turning to port is a definite No-No, as I understand it.

[/ QUOTE ]

If you are far enough away to deem that risk of collision doesnt exist, you can do what you like - and the distance is your call as long as it's reasonable. For me, I think it's between about 3 and 5 miles depending on what's going on, but dont quote me cause I decide at the time based on the individual circs. and it's usually intuitive, so I dont consciously know I'm doing it.

Turning to port to avoid a collision is not recommended, (and definitely not in reduced visibility), but it isnt a No No, as long as you are the give way vessel. If you are the stand on vessel, turning anywhere is a no no, until you are either past and clear, or the give way vessel cant avoid a collision by his actions alone.
 
Re: So much for AIS and DSC.

Yeah, yeah you and Jimi are right and I had thougt about turning to port as one of my options, but finally decided it against it. In writing brief posts, its difficult for some us to be 100% black and white, when there are several shades of grey involved...
 
Re: So much for AIS and DSC.

Whilst we're right, in that you could have turned to port, I always believe that the decision you make on the day is the right one for that day, and there's nothing to suggest that it wasnt.
 
Re: So much for AIS and DSC.

mark 1 eyeballs and hand bearing compasses are all ok but they are better in daylight than at night, is it a big ship a long way off or a small one close up? in the day time none of this is a problem provided there is no fog, I came back from Ijmuden a couple of weeks ago you cant avoid a night passage if you go direct, and its probably twice or three times as busy with shipping as some of the routes described above, Ive got radar with marpa and still had a couple of occasions when I thought it prudent to dramatically alter course as the information was changing all the time from safe to marginal to bl...y dodgy, none of this kit is really very good. But during the day who needs it?
 
[ QUOTE ]
We had no radar, but anyway we would have had no power to run a radar. We were not running a plotter as there was no land within 500 miles and we could not waste the power. That is why I want a simple, standalone, low power AIS receiver that could have squawked when the ship was miles away. It's no use to me to require that I am running a radar, or a plotter, or a laptop to use the AIS signal. It would be nice if I could do that as well, but I need low power consumption, mid ocean, ship spotting, and AIS is the nearest. I guess the alternative is a radar detector but I suspect that AIS is easier to use and more reliable.

[/ QUOTE ]

A basic radar detector is probably more reliable than AIS for your situation. 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) but may not have checked the AIS system since leaving port. I recently questioned the lack of AIS signal from a well known X Channel ferry on VHF, which came to life a minute later, they didn't have clue it wasn't operating.
 
I had a boring trip back from Cher like that on Saturday. Ship to the right, ships to left etc. I just get on and do a bit of cleaning and polishing as I don't have those electrogizmo's to play with /forums/images/graemlins/grin.gif /forums/images/graemlins/ooo.gif
 
AIS offset ?

I can answer that.

The AIS transmission has the facility to offset the aerial position so that the symbol can be centred over the ship - this doesn't mean that all ships have been set up correctly of course!

Homa
 
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