AIS transponder. Now you need it?

[fireball]

Ah yes, of course, that must be the answer. One can never depend on the static data as someone on the bridge has to manually enter it. Its importance is measured by its frequency of transmission - only every six minutes.

However, all the dynamic data is automatically processed and output from the GPS and other active sensors and transmitted at intervals depending on the manoeuvring conditions, with only a few seconds between messages.

The RoRo ferries in the Solent can sometimes be seen facing the "wrong way" to the direction of travel. Probably because 1/2 the time they are going backwards - so their heading is 180° out from the COG ... unless they switch it over ...

 

[BrianH]

Not uncommon, presently seen a rig that is "underway using engine" yet is anchored on 8 point moor and does not have its own propulsion.
Many a ship I have seen passing "Making way under-sail" without a stitch of canvas to be seen
User entered data all prone to error..
Or is it like fishermen who never take there day shapes down....

In many cases a receiver may have been manufactured before the class B protocol was finally defined, it was not formally agreed until well after Class A - it was a sort of an afterthought.

For example, my ancient AIS receiver correctly plots the position and speed of a Class B target but cannot decode any static data for it, which is always blank.

 

[Robin]

Aah, but which version - the international or the DAKA version?

Cheers, Brian.

 

[fireball]

For example, my ancient AIS receiver correctly plots the position and speed of a Class B target but cannot decode any static data for it, which is always blank.

My CP180i doesn't even display class B targets ... bliss!

 

[LadyInBed]

My CP180i doesn't even display class B targets ... bliss!

Mine does.
It's not down to the chart plotter, it is a function of the AIS receiver.

 

[fireball]

Mine does.
It's not down to the chart plotter, it is a function of the AIS receiver.

Ah - sorry to correct you there - but it's a function of this chartplotter's software version - which is old enough to to have ClassB ... the receiver (a Comar) does receive ClassB ...

which is why I had a mild panic attack a few years ago when testing charts and AIS on the laptop down below - which alarmed on an AIS collision. Looked up - I see no ships ... looked at the chartplotter - I see no ships ... looked on the laptop - there's a "ship" ... check again ... it's a flippin yacht .... I don't need AIS to avoid them!!

 

[KellysEye]

I've never bought AIS and never would, they seem a waste of money to me. I've got four Mark 1 eyeballs on board and radar that we only turn on in fog. I'm probably in the minority with that view but it works for me

 

[RobbieW]

When considering whether to install an AIS or RADAR transponder, I went with a dual band radar transponder as the boat already had an AIS reciever - an old NASA AIS engine that I may yet upgrade as it doesnt recieve class B, then again....

I had previous experience of a radar transponder in fog in the North Sea and gained more on my boat crossing Lyme Bay in June. In both cases ships altered for me, they dont know what you are so alter as if you are power driven so take appropriate action! In the second case I could see the large ship situation on AIS so I understood why the RFA behind me slowed until she could overtake as there was a tanker coming the other way over on my port side.

Of course, I didnt see the two yachts on a reciprocal course going east across Lyme until the old Mk Is picked them up 100 yds away!

I'm still of the opinion that 'shipping' primarily uses radar for collision avoidance in poor conditions. So to me a radar transponder is more valuable than an AIS one as I believe a greater proportion of contacts will be aware of my presence that way.

 

[Conachair]

I've never bought AIS and never would, they seem a waste of money to me. I've got four Mark 1 eyeballs on board and radar that we only turn on in fog. I'm probably in the minority with that view but it works for me

Have you ever sailed with one?

I suspect if someone loaned you one for a month you wouldn't want to give it back at the end. Bang for buck they are right up near the top, less than a second you can see if that smudge on the horizon is a ship and if you need to keep an eye on it or if it's going to miss by miles. Offshore I've watched ships alter course by 10 deg to miss me then go back on course again, and known their name to radio up and say thanks. Then more uncommon is knowing that the ship you're thinking of passing astern is a survey vessil & prob has a 5 mile tow behind. Loads and loads of really useful info.

All for less than the cost of a set of semi posh oilies. What's not to like?

 

[AntarcticPilot]

I must admit I have never seen a ship going in the opposite direction to it's AIS info. Like all aids you have to apply some intelligence to the data presented. One of the main problems is that the filtering the operator can apply to the data in most implementations is very limited.

In general though I find it an excellent aid especially in more complex situations

I have, quite recently. I was about to leave James Watt Dock, Greenock, and noticed an AIS target in the ship channel, apparently heading away from the dock, and so no danger whatsoever. As I approached the dock entrance, I was astonished to note that the target, while still apparently pointing away from the dock, was in fact about to enter it! No problem - all seen in good time, and I just did a circuit of the dock. But the target was a RoRo ferry (one of Calmac's finest). Of course, this was double-ended, and no doubt someone had forgotten to tell the electronics which was was the front of the vessel!

 

[LadyInBed]

expect me to embrace the technology and trust it in bad vis? . . . . but at the moment its eyeballs and radar on my ship.

In bad vis, I am grateful for any source of data.

 

[Conachair]

and you guys who "LOVE" AIS expect me to embrace the technology and trust it in bad vis? DREAM ON and on and on and on; clearly its not finished yet. It shouldn't take a "someone" to do anything to it, as soon as it needs a "someone" to give it that sort of vital data like what way am I going its had it I am afraid.

Another product launched before it was ready if ever there was one, when its fixed I may consider it but at the moment its eyeballs and radar on my ship.

Position, SOG and COG are the vital data and they are automatic, they are the one's you'd be interested in. From that you get range, bearing and CPA. Immensly useful. I can't see where the heading 180 deg out comes from, I thought heading came from the ships gyro compass, nothing to do with human intervention.

No one expects you to do anything, but once you've used a set for a few weeks you will probably sing a different song. It works and works extremely well.

Virtual ais buoys are on the way as well, http://www.gla-rrnav.org/radionavigation/ais/virtual_aton.html You'll need more than eyeballs and radar to see them.

 

[chanelyacht]

However ...
the majority of ships still use Radar - and CG can still use Radar too ..

No we can't.

The only CG station fitted with radar is Dover for the Channel TSS.

 

[BrianH]

and you guys who "LOVE" AIS expect me to embrace the technology and trust it in bad vis? DREAM ON and on and on and on; clearly its not finished yet. It shouldn't take a "someone" to do anything to it, as soon as it needs a "someone" to give it that sort of vital data like what way am I going its had it I am afraid.
Another product launched before it was ready if ever there was one, when its fixed I may consider it but at the moment its eyeballs and radar on my ship.

You would be glad enough to have such a simple device once you have had the experience of a high-speed ferry coming straight at you at a distance of 1,1 NM and with a closing speed of close to 40 knots to be glad of the name of the ship to call on channel 16 - as I once did. My boat is the large red arrow, the ferry is the small red icon. As soon as I had finished transmitting it veered sharply to starboard and missed me by a cable. What the display data doesn't show is the name as that column is scrolled off to the left of the window.

 

[Cookee]

Forgive me if this has already been covered but has anyone given any thought to the use of AIS in an emergency? Coupled with a DSC alert it would enable the emergency services to find you double quick I would have thought?

 

[NPMR]

Forgive me if this has already been covered but has anyone given any thought to the use of AIS in an emergency? Coupled with a DSC alert it would enable the emergency services to find you double quick I would have thought?

This was part of the point I was making in the OP and the CG.

From what I'm seeing in these posts, the ideal situation is AIS and radar but for those of us on a small boat with limited budgets and limited electrical power, that isn't an option.

Radar is obviously great at seing more than just ships but al least if you have AIS, it gives you ships locations and actions. Ships will have radar but that may not 'see' a yacht, as we have been told many, many times.

So it feels as though an AIS transponder has a good place in the list of desirable/essential kit for those of us who go into areas where the ships are to be found. And who can't afford radar.

Unless poor people shouldn't go boating unless they have all the kit? (tongue now removed from cheek)

 

[Elessar]

NO NO NO. You need to comply with colregs.

Quite right. Standing on is an obligation not a thing to do if you feel like it.

There's a thread going on about AIS in the MOBO bit at the moment.

http://www.ybw.com/forums/showthread.php?t=298619

Don't be put of just because daka started it

An AIS receiver is in my opinion the best £100 you can spend for collision avoidance information.
And a transponder in a yacht going offshore is very, very useful. Ships can, and do, call you up by name.

 

[Elessar]

No we can't.

The only CG station fitted with radar is Dover for the Channel TSS.

Surprising. And interesting.

 

[BrianH]

Barnac1e why did you leave it until the target 1.1 NM off before you did something? Why do you think he didn’t see you – we have a see me – IT WORKS.

I couldn't believe a professional seaman would leave it so long - clearly no one on the bridge was visually monitoring the way ahead. So it was a little bit like the rabbit in the headlights syndrome. Probably relying on radar and I have no active responder. I prefer to be responsible for my own reactions and not somebody else's.

Edit: If you examine the screen plot, you will see that a complete change of course was made towards me at 2 NM away, giving me only a minute or two to be warned and decide a course of action at such a closing speed.

But the Adriatic is full of cowboy ferry drivers and it was because of an earlier experience when I had to power away from one that was overtaking and would have sunk me if I hadn't, that I bought an AIS receiver.

It sits below and warns me of a CPA - so simple and cheap that, as another poster put it, "what's not to like?"

A happy New Year and a collision-less one to you too!

 

[AntarcticPilot]

Position, SOG and COG are the vital data and they are automatic, they are the one's you'd be interested in. From that you get range, bearing and CPA. Immensly useful. I can't see where the heading 180 deg out comes from, I thought heading came from the ships gyro compass, nothing to do with human intervention.

No one expects you to do anything, but once you've used a set for a few weeks you will probably sing a different song. It works and works extremely well.

Virtual ais buoys are on the way as well, http://www.gla-rrnav.org/radionavigation/ais/virtual_aton.html You'll need more than eyeballs and radar to see them.

But if the ship's head may be at either end of the vessel, it can easily be 180 degrees out. The basic "Quick look" display simply shows ships head, NOT COG etc; these are buried deeper in the display information and although they may be more reliable they are not part of the information available at a glance, at least, not on my chart-plotter.

Don't get me wrong - I thing AIS is a "Good thing". It tells me of traffic I can't see in the ship channel to Glasgow, for example. But it can be misleading, and perhaps those who have their plotter at the helm may not appreciate that those of us who prefer it at the chart table see things rather differently. For me, a quick look now and again is all the plotter gets - most of the time I don't need it; I prefer to navigate by eye. SO, information buried in information boxes is simply not usually going to be seen. And the alarm mechanism is not much use; where I am it gets set off by large commercial vessels moored in the dock, so I tend to ignore the alarm!