AIS Radar

[xcw]

I currently do not have radar and am considering purchasing a set for general coastal cruising and the occasional cross channel trip (in fair weather). I have read about AIS sets, it their reduced functionality over a conventional set adequate for the occasional use I would put it to? I would welcome your views on their pros/cons.

 

[fireball]

I suggest you do a search on these forums - been discussed at reasonable length ...
quick summary for you though:
AIS - great for boats who can't have traditional RADAR (cost or fitting) but will not give the complete picture
RADAR - gives a better picture, but you have to know how to use it and is more expensive.

IMO AIS is probably better than nothing but don't rely on it 100%. There are a great deal of vessels not transmitting AIS due to size and operations. RADAR is the better way to go and there are loads of cheaper sets now available - review in YM? a few issues back. That said - there are 100's of small boats doing X-channel with little or no NAV aids - and they seem to make it ....

 

[srm]

NASA Marine's misuse of the term Radar for their AIS reciever is misleading and potentially dangerous.

Contrary to NASA PR letter in PBO, RADAR is an acronym for Radio Detection And Ranging (not radio direction ... as they claim.) Radar is an active system that transmits a radio pulse and listens for an echo and can detect a a wide range of different targets such as buoys, land and vessels under 300 tons which do not transmit a VHF message saying where they are etc.

AIS stands for Automatic Identification System and simply displays information transmitted from most ships over 300 tons. It can not show anything but information from those transmissions so will not help you avoid buoys, fishing boats, rocks and cliffs etc etc.

It is rather sad that an otherwise good company that produces reliable leisure electronics at a fair price should stoop so low as to try and Hijack the long established term radar to sell what is otherwise a good piece of kit with a graphic display that makes the transmitted ship information easilly understandable.

If anyone from NASA Marine should read this you may like to turn your talents to producing a real radar set for small boats at a fair price - the market is there.

Sean

 

[Colvic Watson]

Many equipment purchases are made because of what is possible, rather than what is best. I can't afford £1000 for the very very cheapest radar. But I may be able to afford £220 for AIS with all its safety benefits. I'd rather have radar, but I'd rather have AIS than nothing.

 

[BrendanS]

What advantages? There are very few compared to Radar. AIS only shows commercial shipping, so only of use if you sail in areas where you might collide with a commercial ship. Pretty much useless in finding your way home in dark or fog in most areas

 

[Rowana]

[ QUOTE ]
NASA Marine's misuse of the term Radar for their AIS reciever is misleading and potentially dangerous.

Sean

[/ QUOTE ]

Couldn't agree with you more !

They should be prosecuted under the trades description act ! !

 

[Gordonmc]

There was a long justification for the use of the term "radar" in relation to AIS which I won't bore you with. I don't think it has much bearing on the value of the system for small boat people.
The real issue is that while it may be compulsory for commercial vessels to have AIS, many don't have the kit switched on. Many owners don't want competitors knowing where their vessels are with what cargo and what their likely ETA is going to be.
So you might see and be able to identify AIS active vessels on your screen... but not the one coming up your stern.

 

[Robin]

There are radars available well under £1000 (I've seen below £800) not to mention secondhand ones. The NASA AIS will cost around £230 discounted but that doesn't include another VHF aerial at £30 and also assumes you have a NMEA outputting GPS already that you can persuade the NASA to listen to. So at best £260 which I suppose gives you what you pay for - you see 25% of the targets for 25% of the cost. I hope the other 75% aren't too costly.

IMHO AIS is an optional extra to radar, not a cheap alternative.

 

[jonjo]

[ QUOTE ]
What advantages? There are very few compared to Radar.

[/ QUOTE ]
It will indicate a collision threat with a confidence factor equivalent to a highly trained Radar operator.

[ QUOTE ]
Pretty much useless in finding your way home in dark or fog in most areas

[/ QUOTE ]
Don't we all use GPS chart plotters for this these days? Oh got it you mean observing other small craft while getting back into port in a pea souper.

 

[crossbones]

Contrary to what srm says nasa are correct with their claim that RADAR is an acronym for radio direction and ranging. (type that phrase in advanced search on google ) Nasa are also correct using the term radar to describe their equipment. It works in exactly the same way as an 's' mode secondry surveillance radar on an aircraft. There are several million references on google to types of radar other than the conventional pulse radar.
All ships over 300ton and all passenger ships are obliged to carry an ais transponder. That is far from being all vessels but it includes all the big fast ones that wont get out of my way.

 

[Micky]

Quote....
There are radars available well under £1000 (I've seen below £800.

Robin, where can i find a radar for under £1000??? and would it be a complete ready to fit and use system, thanks.

 

[francis39]

"Real" radars using a whirly bit on for less than £1000 - have very poor angular resolution because they have a wide beam width - 7 degrees or more (limited by physics and the size of the antenna). As a result, the display barely resembles a map, let alone a dog's dinner. And it has to be said that small targets often don't get seen either because they do not have a sufficiently large radar cross-section to be seen by the cheapo kit. The power consumption can be a factor, too.

On the other hand, the NASA kit, which is definitely a <u>passive</u> RADAR (try Googling that, too!), should always show big vessels with high resolution, and you can find out what their MMSI number is to ask for a detour or other assistance if you need to. It'll never show little guys who don't have AIS. The NASA unit consumes only about 35milliAmps, I believe, which can be a help.

It's "horses for courses"... and "you get what you pay for"... and any other boring platitudes and old saws you can think of!

 

[wiggy]

Ive got AIS engine £125 linked to 8 year old magelan £60 all feeding old laptop -free- running seaclear chart plotter-free- with my own scanned charts -free. A little time and effort an I have large vessesl plotted on my chart with MMSI name, speed collision warning and all the rest for very little money. OK it has limitations but my boat is a light displacement 25 ft and would not enjoy all that radar weight up the mast. I can not see how radar (of the traditional type) can offer the same features for aything like this sort of budget.

 

[Robin]

You are correct that small scanners have wide beam widths. Actually that makes a target seem BIGGER or at least wider since the rotating beam is 'on' the target for longer. The limitation of cheaper radars is in range which for collision avoidance at ranges under say 6mls is not a problem. Wide beam width will also mean less ability to discriminate between 2 targets close together (like 2 buoys marking a narrow channel) until you get closer, because one target is still on the back edge of the beam whilst a new one is one the front edge.

At least these small but proper radars will see land, buoys, fishing boats, small boats, harbour walls and so on. Suprisingly there are very large numbers of these in areas frequented by most small boats and actually not that many big ships which tend to follow pretty well worn tracks offshore.

 

[Robin]

[ QUOTE ]
That is far from being all vessels but it includes all the big fast ones that wont get out of my way.

[/ QUOTE ]

You won't mind hitting a Sunseeker 65 doing 35kts then?

 

[Robin]

Micky

MES Ltd Tel 0870 122 1099

See pages 34 - 39 of current issue of PBO.

JRC 1000 16nm Radar Mega Deal £699.95 with 12" scanner
JRC 1500 MK2 model with 18" scanner £849.95

The only extra required would be a mast bracket or a pole support.

Robin

 

[Micky]

Thanks Robin.

 

[bigmart]

Nasa may be correct in using the term RADAR to describe their piece of kit.

Being a cynic I still think it was no more than a cheap attempt by their marketing department to fool the gullible.

They have gone a long way down in my estimation. To depths they will find it hard to recover from.

Martin /forums/images/graemlins/frown.gif

 

[Swagman]

Yet another demonstration of how some of us choose to prioritise issues. Who cares what it is called - we all know what it does.

Surely the invention of this instrument which clearly has it's uses to track large vessels when in fog (and for me its those large ones I most fear) is worth more than the issues over whether they call it RADAR?

As many other forumites have tried to point out - the two devices are not competitors - and have complimentary attributes.

The orginal question sought feedback on considering an AIS system as opposed to a conventional Radar.

I'd hope we'd all agree the feedback should vary dependent on planned usage rather than the name of the device.

IMHO were it for mainly cross channel use in summer fogs - I'd elect to install an AIS system.
If I wanted a further pilotage aid for coastal work - I'd go for a conventional radar.
AIS would cost me less.
Radar would require more education.

Cheers
JOHN

 

[Robin]

[ QUOTE ]
IMHO were it for mainly cross channel use in summer fogs - I'd elect to install an AIS system.
If I wanted a further pilotage aid for coastal work - I'd go for a conventional radar.
AIS would cost me less.
Radar would require more education

[/ QUOTE ]

John

Different strokes for different folks I guess, but in my case:-

I rarely use radar (the proper one) for pilotage except in fog. I have used it to enter Poole in 25m visibility in conjunction with a chart plotter and wpts set on a previous chart plotter recorded trackline. The plotter/wpts told me which way to go and the radar told me if someone else was in the way. AIS wouldn't have been any help other than to warn if one of the ferries was on the move.

As far as crossing the Channel in summer fog is concerned, that is my primary reason for having radar and we have had one now for about 16 years. I still maintain that ships are but just one of many risks of collision. In some respects less hazardous because they are concentrated in known areas for the most part, travel in more or less straight lines and are relatively predictable. More hazardous are fishing boats that are very unpredictable in both location (they pop up everywhere) and course changes and other small vessels that are also crossing but which may or may not have radar or know how to use it. These smaller vessels will not have AIS but they are just as dangerous IMO.

Robin