AIS as a substitute for radar?

Nick_H

Nick_H

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www.ybw-boatsforsale.com
Looking for a dayboat/weekender and now narrowing it down to two or three options, one has a radar arch, the others don't, so couldn't have radar fitted.

Now it's mostly for nipping across the solent or over to Poole, so radar not really needed, but i'd like to keep the option of heading over to France or Channel Islands, and as anyone who does these trips regularly knows, you can leave in clear blue skies, and hit thick fog mid channel, or especially around the CI's.

I mentioned this dilemna to the broker and he came up with the idea of fitting AIS, which I thought had some merit. I never rely on radar to pick up every small boat anyway, so in fog I slow down, and reckon I can always manouevre out of the way of a small boat, even if I see them at less than 100 metres. What I don't want is to suddenly find a ship bearing down on us, and travelling at 25 knots, so I could pick them up on AIS. Do all ships need to tx AIS signal now?

So what do you reckon?
 
Its probably a btter than nothing scenario, and if it is without radar I would suggest you go for the Digital yachts transmitter as well, so at leats the big stuff can see you as well as you seeing them (should you have an engine failure and cant manouver - or whatever).

Dont think the lack of Radar is a problem, been across dozens of times and hit fog on a few occasions and never had Radar on board.
 
The answer to your question is , yes ships over 300 tons GRT must transmit an AIS signal, and many smaller vessels do. However yachts and small fishing boats normally don't.

If you are clear about what information you are getting an AIS receiver is valuable, particularly for getting a good picture of what is going on in the shipping lanes. It is not, however a Radar and does not show physical features.

Most reports are very positive about its value as an aid to keeping clear of shipping in poor visibility. It is also either as a stand alone or an engine to link up to a PC or Plotter, cheap.
 
My understanding is that all ships over 20m are required to have AIS fitted by law. But my experience is that they do not all have it turned on & transmitting. On a night passage last week from Falmouth to Portsmouth we passed a considerable number of vessels that were over 50m with no AIS transmissions.
So I would suggest that AIS is not considered as a substitute for radar.
Even so, it is an excellent aid well worth having onboard.
 
If I had to choose between AIS and Radar I think I'd propably come down on the side of radar, because it shows every target, vessels, buoys, land features, not just AIS traffic, and it also acts as a navigation aid and backup should the GPS ever pack in. One day all Radars will have integrated AIS as standard.
 
But it costs about 2 grand or so, whereas AIS is a couple of hundred.

I agree that radar is the ideal, but if you can afford the few grand for a radar to be fitted from scratch, a couple of hundred quid extra for AIS is neither here nor there, so I guess my answer is both!! (if starting from scratch with funds available for radar).
 
Its no substitute for radar. It would be nice to have but from what I have read, its not always that reliable. In any case its not just big ships you need to watch for
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This was taken as we came back from Le Havre - about 4 yachts heading West as we were heading North. We have an old radar and it not only picked these yachts up, but two seagulls sitting on a plank of wood. If you have to choose, I would go with the radar anytime
 
Your picture is a perfect example of what I was thinking. You don't need radar to avoid yachts in that visibility when you're driving a 30' sports boat, you just steer round them when you see them. It's very different if you suddenly see a ship, travelling up to 30 knots, at that distance.
 
IMO AIS isnt a substitute for radar but its so cheap that I'd fit AIS anyway.
As to radar on a 30 foot sports boat - I'd try to fit it but wouldnt loose a lot of sleep if there wasn't room.

Unlike most on this forum, if I had the choice of either a GPS plotter or radar, I'd choose to keep the GPS plotter. I tend to use radar for colision avoidance and more when out in the open sea. A 30 foot sports cruiser is less likely to be doing open passages so the need for radar is less. IMO of course.
 
True Nick. But that was not very bad fog. It can be much much worse than that. My point is that a radar can give you so much information about the environment around you. It can give advanced warning of other smaller boats or a flotilla of them(who might not have slowed down as per col regs); Can confirm you are in a channel by seeing the buoys; Can tell you exactly how far from the coast you are and probably enable you to identify where you are; Can also using the radar's EBL, tell you well in advance whether you need to alter course for a big vessel (although you do really need to have autohelm or a very steady course to do this [although AIS might do this as well - not sure - but you are relying on the ship having switched it on and that it is working properly]
If I could only have one, it would definitely be radar. That said for the small incremental cost, it would be worth having AIS.
One good use of AIS happened to us last year on the MBM Holland cruise. Crossing over to France we could see six or seven ships a few miles off and to starboard of us, apparently heading across our track. Neither we nor a boat we were in company with could make out whether we needed to take action but Blue Finn (MBM's boat) heard us discussing this and using AIS could tell us that they were in fact at anchor. And no we couldn't see the anchor balls
 
I don't need radar to know where I am, i've got a plotter for that, and if the plotter fails i've got a hand held and a chart. Modern electronics are reliable so they wont both fail, and i'm not worried about the satellites breaking down, cos I know what they were put there for. So I know where I am, and with AIS I know where the ships are, which just leaves smaller commercial craft and leisure boats to worry about. Even with radar, I have to worry about them a bit, cos I don't rely on the radar to spot every small leisure boat, so I just have more boats to worry about if I don't have radar. I'm going to be in a fast sportscruiser that turns on a sixpence, but travelling slowly, so i'll have the time, speed and manoueverability to avoid another boat, even if I see it late. I might struggle if a big motorboat suddenly appears out of the darkness at 30 knots, but if they're doing that I'd bludy hope they have radar, and i'll have a nice reflector, so they'll know where I am.


I'm not suggesting AIS makes radar redundant, i'd always have it on a cruiser, and i'd have it on a sportscruiser if it was practical to fit it. My question was whether I should not buy a boat, just because I can't fit radar to it and I want to cross the channel occasionally.
 
I have the same challenge-dumb Norwegians /forums/images/graemlins/grin.gif
I ve toyed with the either the AIS receiver only, or the transmit/receive version.
So far, I ve concluded I dont really need it.
 
No idea if this is any help but the Scanstrut demountable poles for radomes are very good pieces of kit although pricey I believe. Meant for saily boats but I don't see why they shouldn't work on a power boat provided you don't try and use it at too high a speed. Presumably you wouldn't be hurtling around in poor vis when you really need it anyway.

http://www.scanstrut.com/products/product-page.php?range_id=10006&type=Sailboats
 
As a raggie, I had radar on my old boat and regularly sailed channel and down to La Rochelle. I reckon I only truly needed it twice in about 4 years.

Having changed boat 18 months ago, I now only have AIS. Have not missed the radar so far.
 
The boats without the radar arch are Windy 32 or 34, and I think a proprietary stainless steel arch would spoil the beautiful lines that attract me to the boats in the first place. I like the idea of a removeable strut, but with a scanner on top would be a PITA to store and fit, and the scanner could get damaged.

The more I think about it, the more i'm convinced that AIS, low speed, and keeping a good watch are adequate, and radar is preferred, but not essential, for channel crossings.
 
Hi
Just a thought but if you liked the boat without the radar arch you could always have a stainless frame bespoke made to suit the boat/radar. I have seen this done to a Jeanneau mf to great effect.
 
Thing is about radar. You dont need it, untill you need it. A bit like a life raft. I have radar and use it about twice a year. I have no life raft. But I nearly needed the dinghy once.

I first bought radar after a horrble trip round North Wales. Only about 9 miles. THing is about radar, it reinforces a chart plotter.. Or maybe disagrees?? Never known that. With radar, you can see what is heading towards you, what it is is hardly imporant.
 
No way should AIS be considered as radar sub.

Its a good aid at best.


There have be numberous cases where AIS transmissions are faulty or indeed none transmitted on ocean ships where there is a requirement to carry ONE and to transmit but no back up required if failure.......


All this said i agree for the use your Solent boat will have you can live without radar and keep an eye on the Wx forecasts.
 
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