In praise of AIS

[doug748]

I want one! This looks like an intelligently-designed, easy to use piece of kit. I'm also well-convinced with their sales argument that it avoids the clutter of AIS overlay on a chartplotter (which I don't have).

But, as I first have to buy and fit a DSC VHF (which I also don't have), I'm wondering whether the Standard Horizon combined VHF-AIS unit will be a more cost effective route? ....

This would be your cheapest route:

http://www.nasamarine.com/proddetail.php?prod=AIS_radar

About 200 quid, it just needs to be connected to any GPS or plotter (with appropriate output), so it knows where it is.

I have had one for about 5 years. They have a number of shortcomings and lack the social cachet of more expensive alternatives. In use they do the job well, with no frills.

 

[emnick]

AIS

i find THE CPA on AIS great so long as it is used with HB compass( or EBL on radar) CPA could be behind you or in front. HB Compass will tell you which way it will pass. It's amazing how the ferries make subtle changes to their course so as most passengers do not even realise that the ship has changed course. Would AIS have prevented the tragedy recently involving the Pride of Bilbao??

IMHO small boats should be banned from transmitting (when in shore)as it just clutters up the screen, the big boys ASAK don't look at it and not interfaced with their radar etc next time out look how many boats are still transmitting when tied to the pontoon

Great piece of kit though

 

[doug748]

i find THE CPA on AIS great so long as it is used with HB compass( or EBL on radar) CPA could be behind you or in front. HB Compass will tell you which way it will pass. It's amazing how the ferries make subtle changes to their course so as most passengers do not even realise that the ship has changed course. Would AIS have prevented the tragedy recently involving the Pride of Bilbao??

IMHO small boats should be banned from transmitting (when in shore)as it just clutters up the screen, the big boys ASAK don't look at it and not interfaced with their radar etc next time out look how many boats are still transmitting when tied to the pontoon

Great piece of kit though

I was troubled by the CPA thing but found that if I zoomed right in, as tight as possible, it was possible to pick if the target was passing in front or behind, in a similar fashion to the Nasa unit.

A very good point about inshore use.
Even large ships are changing course, coming out of harbours in large arcs, setting new courses to round headlands etc; fishing boats are laying pots at slow speeds on constantly changing headings; yachts are tacking, as you are yourself. All this means a that a guard zone becomes a right pain and better switched off. In my view, 3/5 miles out is when AIS comes into its own.

 

[Blue5]

It would certainly be a great asset if the AIS indicated CPA as passing ahead or astern.

 

[prv]

It would certainly be a great asset if the AIS indicated CPA as passing ahead or astern.

Agree!

As far as I'm aware, the only ones that do this are the Vesper models.

Pete

 

[Porthandbuoy]

Agree!

As far as I'm aware, the only ones that do this are the Vesper models.

Pete

The graphics in OpenCPN make it quite clear where the CPA is in relation to you.

 

[BrianH]

The graphics in OpenCPN make it quite clear where the CPA is in relation to you.

Agreed, as does OziExplorer that I used until switching last year.

Here are the screenshots of a freighter that overtook me recently - the first produces a CPA and TCPA but in a separate window that doesn't get included in the screenshot. The second after it had altered course to give me more clearance.

 

[Conachair]

This would be your cheapest route:

http://www.nasamarine.com/proddetail.php?prod=AIS_radar

About 200 quid, it just needs to be connected to any GPS or plotter (with appropriate output), so it knows where it is.

I have had one for about 5 years. They have a number of shortcomings and lack the social cachet of more expensive alternatives. In use they do the job well, with no frills.

Yep, I´ve had one for a while, does the job and current draw tiny. Just got an ais engine for opencpn on the laptop which is fab but with the increased power. The nasa alarm is also loud enough to wake me up solo offshore. Money well spent, possibly the biggest bang for the buck of anything on the boat.

 

[PaulGooch]

The graphics in OpenCPN make it quite clear where the CPA is in relation to you.

Was out at the weekend tinkering with OpenCPN on a laptop, experimenting with some options for my next boat. I've got the sounder and AIS connected to a multiplexor with Bluetooth. The multiplexor is wired to a 5" Garmin plotter, so i get the depth and AIS on the plotter and on the laptop via Bluetooth. Both worked very well.

IMO, AIS works vastly better when overlaid on the plotter.

 

[kyleview]

Do people read previous posts before replying - I really have my doubts as some are really dumb / thick and show absolutely no understanding in their replies of what's been previously posted - in this case JUST TWO pages!.

 

[wadget]

i find THE CPA on AIS great so long as it is used with HB compass( or EBL on radar) CPA could be behind you or in front. HB Compass will tell you which way it will pass. It's amazing how the ferries make subtle changes to their course so as most passengers do not even realise that the ship has changed course. Would AIS have prevented the tragedy recently involving the Pride of Bilbao??

IMHO small boats should be banned from transmitting (when in shore)as it just clutters up the screen, the big boys ASAK don't look at it and not interfaced with their radar etc next time out look how many boats are still transmitting when tied to the pontoon

Great piece of kit though

Speaking as one of the "big boys" (third officer on a large tanker) AIS is incredibly useful for spotting yachts and fishing boats at long range especially in poor visibility.

Actually on all modern ships bridges (post 2005ish) and on an increasing number of older ships the ais is intergrated with the radar which is great considering how weak some of the radar echos are from small targets at medium to long range. Bearing in mind that as the give way vessel I like to alter course at 6-8 miles, which yachts are often not visible at in all but the best visibility.

Also please do not use the VHF to call ships for collision avoidance, as any well trained officer will ignore you, and the rest will probably struggle with english just making the situation worse.

 

[Blue5]

Also please do not use the VHF to call ships for collision avoidance, as any well trained officer will ignore you,

Thats an interesting take, care to explain a bit more.

 

[CaptainBob]

Also please do not use the VHF to call ships for collision avoidance, as any well trained officer will ignore you, and the rest will probably struggle with english just making the situation worse.

What if it was a DSC call to your specific MMSI, would they ignore the alarm?

We have on occasion had call to speak to large merchant vessels and they answered, and despite language differences we both understood each other well enough.

 

[Cookee]

Our boat would struggle to keep a radar on the roof but I have to say the AIS was brilliant coming in to Edinburgh in the driving rain and fog showing up all of the commercial stuff - passing down the coast and encountering thick fog we passed many smaller fishing boats setting or retrieving pots and none of them had AIS on board which was quite scary as they passed by in the murk. (we had slowed down to 6mph with an on deck lookout!)

Our Raymarine setup with an AIS 650 - brilliant!

 

[nigelmercier]

Speaking as one of the "big boys" (third officer on a large tanker) ... please do not use the VHF to call ships for collision avoidance, as any well trained officer will ignore you, and the rest will probably struggle with english just making the situation worse.

I confess, if that is the right word, that I have done this. I think they got someone out of his bunk to answer the DSC call. But surely being able to alert another vessel of your presence is one of the reasons for having AIS?

 

[Blue5]

I confess, if that is the right word, that I have done this. I think they got someone out of his bunk to answer the DSC call. But surely being able to alert another vessel of your presence is one of the reasons for having AIS?

Likewise, without a reasonable explanation it seems a bit of a precious attitude, if they have somebody on watch whats the problem?

 

[Salty John]

I researched this issue a couple of years ago:

VHF discussion regarding collision avoidance is discouraged on the grounds that it is liable to make a bad situation worse, when:
Vessels fail to identify each other correctly.
Vessels misunderstand each other.
Vessels spend too much time communicating and fail to take direct action as a result.

Apparently all the above have led to collisions. The lawyers all agree you should only communicate by VHF in a potential collision situation as a last resort - presumably so that you have used all means at your disposal to avoid the collision.

 

[Talulah]

I researched this issue a couple of years ago:

VHF discussion regarding collision avoidance is discouraged on the grounds that it is liable to make a bad situation worse, when:
Vessels fail to identify each other correctly.
Vessels misunderstand each other.
Vessels spend too much time communicating and fail to take direct action as a result.

Apparently all the above have led to collisions. The lawyers all agree you should only communicate by VHF in a potential collision situation as a last resort - presumably so that you have used all means at your disposal to avoid the collision.

Technology has moved on. I can't remember the report I read since but the vessels were criticised for not talking to each other.
"Vessels fail to identify each other correctly." You no longer hear "Unidentified Vessel on my port beam this is the yacht... etc"

 

[Blue5]

Ok, thanks for that, how close is "a last resort".

Seems a worrying statement that officers are trained to ignore calls to their ship on Ch16.

The couple of occasions I have called them by name I have received a reply and after one call I could see the rudder angle applied to alter course on AIS which made me wonder if I had been spotted.

 

[Salty John]

I don't know what 'last resort' really means, I suppose when all else has failed and the collision is unavoidable you make the vhf call to cover yourself. That would take a cool legal head!

I can understand the view that ships should have enough information available to them to avoid collision situations with each other without resorting to vhf communications, and I can imagine situations in which vhf communication could lead to confusion. I wouldn't argue with the many experts who have studied the situation enough to confidently assert that vhf communication in big ship navigational situations should be avoided.

However, I'm not sure that communications with small recreational craft featured much in the debate. We're much more likely to be overlooked and our cry via vhf might go unanswered but it might not go unnoticed and that might just save a dangerous situation from arising.