AIS transponder

[Rivers & creeks]

On the contrary.
All vessels >300GRT have to have AIS Class A - it is compulsory!!!



All Class A AIS transponder units units have some kind of screen (however small)- again: it's the law.

I agree 100% - they all display it on a three line LCD display showing the numerical lat and long of nearby vessels. Ferries and ships coded since 2004 may well have also integrated it onto new plotters. Ships coded since 2004? - about 5% of the commercial vessels visiting the UK. Then you have to hope they haven't disabled the class B signals as class A sets are allowed to do to reduce clutter on their screens. It's a sterile argument though, we're arguing about different things. The class B transponder makes you feel safer - and that may or may not be a good thing but it's why it's bought - the fact that you appear as a series of digits on a scrolling display is the illusion of safety you've bought. But if it makes someone feel safer then that's no business of anyone else. All I'm doing is illustrating why it doesn't help avoid collisions, but it isn't bought to do that because it can't, it's bought to make someone feel better; hence the discussion never goes anywhere.

A RADAR transponder shows up on every single commercial vessel out there on the screen they are looking at for all their regular navigation, a different beast altogether but much less sexy in marketing terms.

 

[Houleaux]

I singlehand a similar size boat.

Setting up a chartplotter, with AIS input, above the companionway was one of the best things I ever did. It is fairly dry there, right in your field of vision and only needs a short flying lead from the deckhead area. I have made a dead simple wooden bracket so the thing can be removed to the chart table when not under way:

View attachment 38042

If I could justify the spend I would follow pvb and Old Varnish and fit one of those Echomax dual channel radar botherers, as well.

+1. I've flush mounted a Standard Horizon CP180 above the companionway (fits perfectly) and interfaced this to their GX2100 AIS VHF Radio (mounted below decks). A very useful combination - my only criticism of which is that the display is too bright at night.

 

[Koeketiene]

Ferries and ships coded since 2004 may well have also integrated it onto new plotters. Ships coded since 2004? - about 5% of the commercial vessels visiting the UK.

Where do you get this figure from? (genuine question)
Because it certainly does not match my own personal experience.

 

[Rivers & creeks]

Ooops, sorry it's a while since I looked, it's now 88% pre 2004. Which means 12% of ships will see more than a scrolling numerical display of various targets lat and long. If they haven't temporarily disabled class B signals. But like I say, that isn't why people buy AIS transponders, they buy them because marketing types persuade them that their vessel and the their crew deserve a transponder, like the ads say "because you're worth it", that's fine, just a different rationale.

 

[prv]

If by 'ships' you mean merchantmen: use of AIS is compulsory for every vessel over 300GRT. They may not always be keeping a close eye on it, but that goes for radar as well.

I can only speak for the two ships' bridges I've spent time on at sea. They both had a small text readout of AIS which was generally ignored, and a large CRT radar screen that the OOW kept a very close eye on, and sat in front of when not doing something else.

Most deck officers will have used radar as an integral part of their job for the entirety of their career. To many of them, AIS is a newfangled toy which "is dangerous to use for collision avoidance" (we've had professional seafarers stating those views on these forums within the last few months).

So no, "they may not be keeping a close eye on it" does not apply equally for AIS and radar. In terms of both the equipment and the people, radar is king on the bridge of many ships.

Of course, as I said in post number five, the proportion of ships with effective AIS displays is presumably increasing. And one hopes that the attitudes are changing, to use both AIS and radar for maximum effectiveness. My gut feeling is that Lazy Kipper's 5% statistic is overly pessimistic; more ships than that probably have integrated ECDIS that displays AIS along with radar data. But I have no real data to go on - it would be interesting to see some reliable evidence (if such exists) of what proportion of ships in UK waters have AIS as a primary instrument and use it as such.

Pete

 

[prv]

That's the problem. We were sailing Guernsey - Jersey this summer, reasonably close to a guy broadcasting his AIS position on 'B'. Everytime the gap between us closed a bit my AIS alarm would sound and I needed to cancel it. I'd have turned it off completely, but viz wasn't good, and I wanted to know when the Condor cats were coming.,

That's why I recommend the Vesper displays. You could have turned off alarms for that yacht only, while leaving the rest enabled. Or if there had been many yachts, set a speed threshold so that boats pootling along at five knots (or whatever you chose) wouldn't set off alarms but you'd still be warned about the Condor zooming in.

Their newer touchscreen displays I believe allow you to be even more specific, eg saying "always alert me to the Condor, even if other alarms are off" (of course you do need to know the Condor's MMSI, eg from seeing it once before). But I prefer the simplicity and very low power use of their original monochrome range with physical buttons.

No, I'm not on commission, but I think they deserve the publicity.

Pete

 

[Koeketiene]

Ooops, sorry it's a while since I looked, it's now 88% pre 2004. Which means 12% of ships will see more than a scrolling numerical display of various targets lat and long.

You don't say WHERE you got the figures (genuinely interested)

But like I say, that isn't why people buy AIS transponders, they buy them because marketing types persuade them that their vessel and the their crew deserve a transponder, like the ads say "because you're worth it", that's fine, just a different rationale.

I bought mine (and a radar) after a couple of Channel x-ings in (thick) fog.
The last one in particular was quiet scary. The only indication I got of some merchant traffic was the smell of their exhaust and then passing through their wake.
Now I have an AIS transponder liked to a laptop running OpenCPN. Looked at receivers too, but the price difference did not seem too substantial in the great scheme of things. And... if it doesn't help, it doesn't hurt either.
Plan to have it on 'passive' most of the time and only to have it on TX when the situation warrants it - such as restricted visibility. In such conditions it is also unlikely that the big boys will filter out contacts.

Each their own...

 

[Koeketiene]

So no, "they may not be keeping a close eye on it" does not apply equally for AIS and radar. In terms of both the equipment and the people, radar is king on the bridge of many ships.

In congested waters such as the Channel certainly, and the more experienced bridge officers will be on watch too.
But once clear of them, the 'cheap & cheerful' crew will be on watch.

 

[Daydream believer]

I singlehand a similar size boat.

Setting up a chartplotter, with AIS input, above the companionway was one of the best things I ever did. It is fairly dry there, right in your field of vision and only needs a short flying lead from the deckhead area. I have made a dead simple wooden bracket so the thing can be removed to the chart table when not under way:

View attachment 38042

If I could justify the spend I would follow pvb and Old Varnish and fit one of those Echomax dual channel radar botherers, as well.

no room on the bridge deck
( Note the upwind speed !!!)

View attachment 38044

 

[prv]

In congested waters such as the Channel certainly, and the more experienced bridge officers will be on watch too.
But once clear of them, the 'cheap & cheerful' crew will be on watch.

And cheap crew use AIS instead of radar?

Pete

 

[ShinyShoe]

Just checking, you do know that 95% of all commercial ships do not have a plotter screen showing AIS targets? When you say that a transponder means that they 'know you're there' it means that your lat and long appear on a numerical display listing you and the three other closest targets. Sure, all new codings have to have a plotter type display for AIS so you've got to hope that the ship that's nearest has been built in the last five years or so.

Doesn't just apply to new builds does it? Does it not apply to all new codings? Any change of owner requires re-coding. I get the impression quite a large proportion of ships change owners relatively frequently.

The article argued it was better to have nothing, as then you paid alot more attention !

Given the context of the OP - single handed in the channel - Surely we aren't suggesting he doesn't even have a passive reflector as it will keep him on his toes...

One thing about an AIS receiver is that it gives you ship MMSI numbers, which you can use to call the vessel and check their intentions.

BUT - beware that there have been collisions while people try and clarify intentions via VHF. The ColRegs make no mention of clarifying intentions via VHF... But I have to say knowing a vessels MMSI seems very useful. Perhaps its not the big ship's MMSI that interests so much maybe its a relatively close yacht... Maybe its someone who might be able to help or you may be able to help who's struggling etc.

I agree; that way you get all the benefits of AIS receive plus your blip appears on 100% of ships' RADAR screens; without the dangerous misconception that your class B transponder is showing up on more than a handful of ships.

Only if they've set their RADAR correctly. There are a string of MAIB collision reports that show that doesn't always happen... I think you are at risk of assuming with active RADAR responder that you WILL be seen...

What is true is that in congested areas (like the Solent) some/all merchantmen filter out Class B AIS as the screen would be too cluttered with contacts to be of any practical use.

But if I look at AIS online in the Solent its busy, but not crazy. Yes I know that could / will get worse. But I think the answer is to zoom the chart in more, and reduce the CPA Zone.

Assuming they then remember to switch filtering off I'd expect it would be less of an issue with Class B clutter in the Channel?

Its a brave Master who filters out an aid to navigation. I'm trying to imagine the discussion with the MAIB inspector when you run someone over... "Ah, yes I wouldn't have seen them on AIS as I was filtering out those pesky Class B's... ...they just get in the way making it look like I'm going to crash into them all the time." "Is that what you did? Crash into them I mean?" "Erm, well, Erm, kind of. But I'd prefer to look at it as they crashed into me, afterall I'm transmitting Class A AIS and they are Class B so I'm more important, aren't I?."

All I'm doing is illustrating why it doesn't help avoid collisions.

That's a bit of a blanket sweeping statement.Do you genuinely believe a Class B Transponder has never prevented any collision?

And cheap crew use AIS instead of radar?

Pete

Well I can use AIS but am not trained to use RADAR... I'm sure a watch keeper needs to be trained to use RADAR but if at a glance I could see all the things round me with names on I know which I'd use. Trouble is not all the things he wants to see will be on RADAR. The best system I've ever seen overlayed AIS, RADAR and a chart. So you see a blip on a RADAR but its tiny... but it has an AIS super-imposed you know its a plastic boat. Or you see a blip on RADAR but no AIS and you can go check out the window..

 

[prv]

I'm sure a watch keeper needs to be trained to use RADAR but if at a glance I could see all the things round me with names on I know which I'd use.

What if your AIS looked like this?

That is all that ships were originally required to carry. According to Lazy Kipper's figures, it remains all that 88% of ships visiting the UK are required to carry today (though of course some may optionally carry more).

The best system I've ever seen overlayed AIS, RADAR and a chart

Yes - on a ship's bridge that's called ECDIS, and as I said earlier, newer ships are likely to have it. But I want to be visible to all the ships, not just the new ones.

Pete

 

[BrianH]

Since 2007 I have had an AIS receiver installed on my 31' boat initiated by a frighteningly near-miss with a high-speed ferry in the Adriatic. Incredibly, a later incident occurred when a 33 knot ferry was coming straight at me and at 1.1nm and less than 2 minutes away I called him on VHF using his name from the AIS target report whereupon he instantly sheered away. I therefore consider an AIS receiver a valuable safety aid.

An AIS transponder is a different case. From 'The Pilot' the magazine of the United Kingdom Maritime Pilots' Association, of a couple of years ago - may no longer be so relevant:

"With respect to the type of equipment installed, the overwhelming majority of vessels are fitted with the minimum required to comply with carriage regulations! These are small alpha numeric displays which at the absolute basic level have to display at least three targets. I have seen such minimal three line units on ships and for all practical purposes they are totally useless. Other systems cram a list of many targets into the small display (typically 9cm x 12cm) which renders them illegible and again these are totally useless.

It is of extreme importance to the Class B user to be aware that there is no statutory requirement for SOLAS vessels to be able to display AIS targets on a screen merely a requirement to provide a simple alphanumeric Minimum Keyboard and Display (MKD). To meet the minimum requirements this display need show no more than three ships at any one time detailing bearing, range and name of ship. Therefore Class B users must understand that their vessel may not be appearing as a ‘bright beacon’ on the displays of the majority of SOLAS vessels. Although IMO requires all new radars fitted after 1 July 2008 to have good AIS display capabilities, existing radars will not have to be upgraded and so it will be many years before AIS data can be effectively used for navigation on many SOLAS vessels." ​

And a comment from a deck officer of a US registerd vessel with full SOLAS conformance:

"We have a tiny 5 line display on our 250 million $ ship. Useless for ships and useless for boats."​

 

[Koeketiene]

I'm sure a watch keeper needs to be trained to use RADAR but if at a glance I could see all the things round me with names on I know which I'd use.

My point exactly.

What if your AIS looked like this?

What your AIS kit looks like matters very little.
What matters is what it is linked to. Few AIS sets are meant to be used as stand-alone.

Mine looks like this:

On its own of very little use, yet once linked to a laptop running OpenCPN...

 

[Storyline]

I was in the market for an AIS transponder but reading this thread has convinced me that an active radar responder has to be higher up the shopping list. I have always seen them mounted at the top of the mast but would there be that much difference if it was mounted on the pushpit/taffrail ?

 

[sailorman]

I was in the market for an AIS transponder but reading this thread has convinced me that an active radar responder has to be higher up the shopping list. I have always seen them mounted at the top of the mast but would there be that much difference if it was mounted on the pushpit/taffrail ?

The radar will be "line of sight" so the higher the better it will be with shipping

 

[onesea]

I was in the market for an AIS transponder but reading this thread has convinced me that an active radar responder has to be higher up the shopping list. I have always seen them mounted at the top of the mast but would there be that much difference if it was mounted on the pushpit/taffrail ?

I would make sure its dual band... Apparently its good practice to have 2 radars on different range scales. You might be a blip on one and not on the other!

 

[Storyline]

The radar will be "line of sight" so the higher the better it will be with shipping

Yes, but assuming the radome of the ship will be many feet up or so would mean I would show up at more than six miles. I suppose one problem is that it may be shadowed by the coachroof. Just want to avoid the hassle of running another wire up the mast !

 

[ITH]

Yes, but assuming the radome of the ship will be many feet up or so would mean I would show up at more than six miles. I suppose one problem is that it may be shadowed by the coachroof. Just want to avoid the hassle of running another wire up the mast !

Recommendation (below) is from the MCA Guidance Note "Carriage and use of radar reflectors on small vessels." URL="http://www.sea-me.co.uk/pdf/Guidance.pdf"

3.5 Many operators of radar systems use automatic guard zones set at 3nm to 5nm, to warn of
approaching vessels and a consistent radar target response is important to trigger this
function. It is emphasised that the reflector must be mounted at a minimum height of 3m
(preferably 4m) above sea level to take it out of any wave obscuration effects and give a
potential detection range of 5nm, which was used in setting the ISO 8729 criteria.

 

[Storyline]

Thanks ITH top of the mast it is then. Also gives me the reason the replace the suspect vhf coax.