AIS "radar" information please

Re: AIS \"radar\" information please

Before GPS we used radar for nav while today one uses it for nav only in very close-quarters situations. Radar is excellent at very close proximity. In March 2000, at Dover, in fog so thick I could hardly see the bow of the Centaur, (with the Harbour Authorities permission) I motored across the harbour and right into the channel to the marina. I didn't see anything until I could reach out and tie up. You wouldn't do that with GPS and AIS doesn't figure.

I also often use the radar when the genoa is restricting forward visibility. In July 2003, single-handing the Centaur out of Fowey across Mevagissey Bay, I almost rammed a small fishing boat - just did not see him. Now, when single and short handed with a genoa blocking forward viz, I keep the radar on. Power is seldom a problem with modern radars even on a very small yacht.
 
Raise them on VHF?

"Please, your Honour, I know we hit but I had been trying to raise them on VHF. But they didn't answer, even though I called and called. And meanwhile they were getting closer and closer, and I still couldn't raise them. They couldn't have been listening properly."

We all know this is an old and all too fequent story which the MAIB hears many times.
 
Re: GPS versus Compass?

[ QUOTE ]
GPS depends on battery power, GPS signals (courtesy USA), the GPS set itself, etc etc. All have a risk of failure when compared with the earth's magnetic field. The compass wins.

[/ QUOTE ] If you won't allow a GPS on the grounds of it needing a power supply then you can't have a radar /forums/images/graemlins/smile.gif
 
Re: GPS versus Compass?

Type colon then close parenthesis like this /forums/images/graemlins/smile.gif or click on one of the little buttons like /forums/images/graemlins/shocked.gif

/forums/images/graemlins/smile.gif
 
Re: Justify?

We don't have:
Liferaft
Eprib
Survival suits
Helmets
Kneed pads
Elbow pads
AIS (although not what I'd call a safety device)
Radar

Which one should I "justify" first? Or do I say stuff it and get the whole lot? Then what happens when the CC people pay me a visit and ask for their money? Not everyone has large disposable incomes and can afford every safety gadget under the sun in one go. Each bit of kit on board should justify it's existance and although some of the safety kit listed above is desired it isn't mandatory to have.

Equipment on board suits the sailing style - despite "wanting one" we have not run into a situation (yet) where I have felt it was not safe to continue without one - although I'm sure that day will come.

So - we evalute the probability of requiring the safety kit and kit the boat accordingly, hence whenever we go sailing we will be mindful of the limitations caused by our lack of certain equipment.

Justify - what price a life? what price common sense?! I don't race my car, therefore do not feel the need to wear a race suit and helmet whilst driving - although if I did find myself in an accident both of these items (fire proof race suit & helmet) could save my life .... I still don't have them - do you?
 
Re: AIS \"radar\" information please

[ QUOTE ]
AIS and SSR are completely different technologies

SSR is 'attached' and synchronised with the primary radar return. It provides only limited data but is correctly described as radar

AIS is an autonomous ID & data system which provides a whole raft of information, totally independent and asynchronous to any radar fitted

It is most definitely not radar, primary or secondary

[/ QUOTE ]

May I respectfully say "garbage" Mr Tome.

This discussion is crazy. Whilst SSR is often used in conjunction with primary radar as you say, it is by stretch a requirement. (Just an easier way to present range and direction information)

RaDAR is a generic term for using radio information to present positional information. There are a variety of ways of making that work. Suggesting AIS is not RaDAR is akin to claiming that stinkboats aren't boats because they do not have sails. (As the majority of early boats did of course) Just because it works differently does not mean that it is not a boat!

This repeated conversation irritates me because it only serves to undermine what is a useful "additional" safety device. Why would people want to do that?

For the record, we have primary RaDAR, AIS and EchoMax. However, for boats without RaDAR, I can't see any strong argument against fitting. (As to because it only works if other boats have it switched on, please give people some credence.

Back to sleep now.

Peter
 
Re: AIS \"radar\" information please

[ QUOTE ]
I can't see any strong argument against fitting.

[/ QUOTE ] I can't see any strong argument in favour of fitting (other than as an adjunct to an ordinary radar). Could you talk me through the benefits that you see?

If one of the benefits includes calling ships on the VHF, can you talk us through that scenario? What are you going to say to the ships?
 
Re: AIS \"radar\" information please

[ QUOTE ]
RaDAR is a generic term for using radio information to present positional information

[/ QUOTE ]

You may indeed say 'garbage', but you qualify it by sprouting utter bollox, if I may

The origins of radar, as most will know, is in using radio waves to Detect targets.

[ QUOTE ]
Whilst SSR is often used in conjunction with primary radar

[/ QUOTE ]

When is it ever used without? And it isn't an 'easier way to present range and direction information'. The primary radar does this unaided. SSR augments the information with altitude and more recently with additional information

I think you'd already gone back to sleep before you posted this drivel!
 
Re: AIS \"radar\" information please

I agree (doesn't everyone?) about AIS not being a replacement for radar, but I'll be getting one to supplement the radar set. The general point, I think, is probabilities. Yep, maybe not every big ship has the AIS on, but most do, so that's a whole bunch that you're more likely to be able to avoid.

And yes, there are fishing boats, mobos, other yachts, all of which can spoil your day in a collision, but in poor vis, it's only likely to be the big ships still steaming on at 20+ knots, so you have more of a chance of avoiding the others, plus more chance surviving a collision with them long enough to launch the liferaft or get picked up by the other vessel. Like I said, probabilities.

Added to which the fact that I might miss something on radar for whatever reason that gets picked up on AIS.

As for what do you do with the MMSI - well I think that's obvious. "Big Ship, this is Little me, I have you on my radar and AIS and our CPA looks a bit close, I'm planning to alter to x degrees, will you be holding course?" "Affermative Little Me, we were due to alter to y degrees in 10 minutes but will hold on till we're clear of you. Have a safe trip"
 
Re: AIS \"radar\" information please

[ QUOTE ]
[ QUOTE ]
RaDAR is a generic term for using radio information to present positional information

[/ QUOTE ]

You may indeed say 'garbage', but you qualify it by sprouting utter bollox, if I may

The origins of radar, as most will know, is in using radio waves to Detect targets.

[ QUOTE ]
Whilst SSR is often used in conjunction with primary radar

[/ QUOTE ]

When is it ever used without? And it isn't an 'easier way to present range and direction information'. The primary radar does this unaided. SSR augments the information with altitude and more recently with additional information

I think you'd already gone back to sleep before you posted this drivel!

[/ QUOTE ]

Good to see living up to your reputation. You may indeed suggest I am spouting bollox should you be in a position to think so. As it happens that is not the case. The only rational I see from you is that it is not RaDAR cos Tome says so. Well that deserves a bollox me thinks.

The origins of boats did not have engines. So floating things with engines are clearly not boats.

Suggest you get over it and stop using your arrogance to cause confusion.
 
Re: AIS \"radar\" information please

No problem at all. On the last boat I deemed Primary RaDAR to not be feasible. (Space and power) However, we did go across channel. Another aid in reduced visibility in addition to MK 1 eyeball seemed worthwhile to me. And to be frank, this is true inshore.

Peter
 
Re: AIS \"radar\" information please

Once again it was a Scot, Sir Robert Watson-Watt who is widely credited with the practical invention of radar in the late 30's, even though groundwork had been done by Hertz and Maxwell

The marvel of his apparatus was that he could use radio waves to detect aircraft more than 50 miles away. The invention used the acronym RADAR for radio detection and ranging

So it all has very little to do with tome's definition but I can well understand that your ignorance of the subject may tempt you to think my response is arrogant rather than factual. The relevance of this with boats, sails or engines I can only attribute to your obvious state of tiredness - induced or otherwise
 
Re: AIS \"radar\" information please

'twasn't me who wrote it, honest mister /forums/images/graemlins/smile.gif
 
Re: AIS \"radar\" information please

Given that it has been apparant from other threads that some forumites have been confused by the likes of the simple difference between 121 MHz and 406MHz EPIRBs, I fancy it will not be too long before we have forumites telling us that they have one of these new fangled cheap radars that just needs a little cheap antenna on the pushpit and what fools everyone else is for paying megabucks for one of the expensive radars with big radomes, etc /forums/images/graemlins/smile.gif.

(actually I think one forumite may have started down those lines already /forums/images/graemlins/smile.gif).

John
 
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