AIS Class B targets

[PjotrC]

Originally Posted by bcn

- the situation Thomas documented is an extreme one and if you are in a narrow channel with 200 race boats you will be eye ball navigating anyhow (or stop and wait)

Exactly, the point in these cases is not how to use AIS for immediate collision avoidance, but how to find a way to keep it on for broader picture, without too many distractions. Still, dense Class A traffic also happens, and its handling can be improved ...

A quick way forward requiring very little coding:

1. Show Class B as 1/2 size icons
2. First click on "Show AIS" button hides Class B targets, second click on "Show AIS" hides all targets, 3rd click restores all

Not perfect, but simple... I would prefer small vs. large instead of Class B vs. A, but why not start here ...

Then

Next step: target list sorted by CPA

Next step: separate CPA/TCPA warning criteria for Class A and Class B (better: large and small)

I looked at VesperMarine manual at Vesper Marine AIS WatchMate - Setup & Operation Guides . Good thing thay have is the profile system for composite configuration settings, but their filter mechanism is relatively limited - it only looks at speed and distance, no class and no size taken into account, and it may be quite confusing what actually is filtered out at given moment. The approach for "Just ECDIS" devices, "Just AIS Display" devices and "Do-It-All" devices", as is OCPN may differ a bit.

In dense traffic all keyboard interventions must be kept to optional minimum, so there should be no absolute need to manually acknowledge alarms and no need to bring to screen the Tools Dialog (Tools -> Ships -> AIS -> scroll down -> set this and that -> Close... too much). All should be controlled by the "Show AIS" button and a few AIS Target List controls always readily visible, for example - radio buttons for 2-4 profiles.

[Littlechay]

Hubert,


Google is your friend, it's not hard to find Vespermarine http://www.vespermarine.com/ and there you'll find everything.

Notice that I never mentioned filtering but target prioritisation which is slightly different; also look at the way it generates alarms.

Chris

[Littlechay]

Originally Posted by PjotrC

I looked at VesperMarine manual at Vesper Marine AIS WatchMate - Setup & Operation Guides . Good thing thay have is the profile system for composite configuration settings, but their filter mechanism is relatively limited - it only looks at speed and distance, no class and no size taken into account, and it may be quite confusing what actually is filtered out at given moment. The approach for "Just ECDIS" devices, "Just AIS Display" devices and "Do-It-All" devices", as is OCPN may differ a bit.

One of the good features in the Vepermarine devices is are the three configurable profiles; Offshore, Coastal and anchored. Perhaps something like that could be implemented in OCPN as an easy switch between the way things are prioritised.

[JeffnLauren]

I downloaded the AIS/Radar like plugin, but am unable to move it to /usr/lib/opencpn. I get the error message saying I don't have permission.

I can change permissions on the ".so" file, but not on the /usr/lib/opencpn folder. A message says I do not own it.

Thoughts?

[nohal]

That is corret, root does own everything there...
You have to use

sudo mv libaisradar*_pi.so /usr/lib/opencpn

Pavel

[JeffnLauren]

Originally Posted by nohal

That is corret, root does own everything there...
You have to use

sudo mv libaisradar*_pi.so /usr/lib/opencpn

Pavel

Thanks Pavel! However I got:
mv: cannot stat ‘libaisradar*_pi.so’: No such file or directory

Do I need to fully spell-out the file name, "libaisradar_i386_pi17_vo96_pi.so"?

Jeff

[nohal]

Jeff...
You sure can, but if you were in the directory where the library actually is you should not have to.

Pavel

[roundm]

Hi All, I hope this discussion has not completely died.

I (and probably many other potential OpenCPN users) need to be able to disable Class B - or at least put heavy filters on traffic (disabling specific vessels, groups of vessels and other complex groupings) AIS data. I sail in the Solent and virtually every day between March and October there is at least 1 keelboat race on in the solent and the problem is that the major race organisers (e.g the RYS and RORC) are using AIS to track vessels.

This leads to the situation where I have vessels that are tacking frequently in fleets of 40 or more boats - sometimes several hundred boats in a race (the RTIR race in June has about 1800 entries). They may be briefly heading in my direction, but will turn long before they get near me. They just add clutter to the screen.

So I have used the filtering available - I have OpenCPN set to warn of a CPA of less than 1 mile, but only if it will happen in the next 15 minutes (TCPA < 15), I've also disabled calculation of CPA on vessels more than 20 miles away.

So we have multiple 300ton commercial vessels doing 15 - 40 knots, I have fleets of boats (Sunsail alone have a matched fleet of 40 Beneteau First 40's - all with AIS transponders and all tacking all over the place) plus other race fleets (on events run by various of the 20 or so sailing clubs in the area) all showing and creating traces. I need to leave the settings I've set for any passage I am on, but around the Solent on daysails the situation is very challenging.

My OpenCPN drives a 19 inch (1440 x 900) screen and I usually have something like a 3 to 5 mile range showing on the screen - and if will often have 20+ danger tracks showing from all these yachts.

The problem is that all these yachts are tacking and manouvering and their tracks hide the tracks of the commercial traffic I do care about. Most of the time I can easily predict where the commercial stuff is going, but sometime they make mistakes, or go somewhere unusual and with all the clutter on the screen it is really difficult to spot this. An AIS CPA warning on this might make the difference between safety and an incident - if I can spot it!

This is not a 1 off occasional situation, it's most weekends and many weekdays in this area. And whilst I completely agree that I'm keeping a lookout for the race guy's (usually trying to work out what they are using as marks - so I can predict where they are going and when they will tack - last thing I want to do is head for a buoy and find they are using is as the turing mark at the bottom of a downwind leg - dropping kites and then heading off on different tacks to get clean air!)

On a busy sunny saturday there will be upwards of 5000 vessels in the Solent -increasing numbers of these are fitting transponders and using them in harbour. At present the ONLY option is to disable AIS completely on these trips - something I'm loath to do as I really think it's a fantastic safety aid (and I think OpenCPN's display of CPA is just about the best there is!)

Any suggestions on how to filter this out ?

for me - I'd like to be able to deselect individual vessels -and to build a database of the vessels I've recieved AIS messages from (So I can tell OpenCPN to ignore the Sunsail fleet for example) This would also speed up the identification of vessels as a side effect. Might be nice to be able to group vessels to watch but disable alarms from (for example to watch a race start for example).

The comments about filtering out Class B being dangferous is right in principle and when on a passage in a lightly traffic'd area. But a screen that is unreadable because of all the warnings and (irrelevant because they will tack and are not following the channels) red targets showing is worse - and the targets hide and confuse the nav information being displayed as well.

I hope this is seen as a real situation that needs help and not an awkward thing to be ignored, I'll get some screenshots in a couple of months time if you don't believe what I'm seeing is real - I have to add that OpenCPN is a great package and I'm not aware of any commercial package or product with a solution to this problem.

Mark

[nohal]

Mark...
Track disabling for individual targets is already implemented in 3.3 beta. I would need a recording of say 20+ minutes of such a busy weekend afternoon on the Solent made with the VDR plugin to implement some more sophisticated ways to filter the targets...

Pavel

[roundm]

Pavel

I'll load the beta 3.3 and have a play

happy to get a log of a (few if you want) busy days - are there specific pieces of data you'd like ? or is it screenshots or something else.

and as it's Jan - I will probably need to wait until around Easter for the sailing season to get busy - it's blowing a F6/F7 at the moment (and it's cold and wet) so most boats are still out of the water.

Thanks for considering it

Mark

[nohal]

Mark...
What I would need is the log of the NMEA stream you are getting (recorded by the VDR plugin) to see how does it feel to be there and test the usability of the changes I implement - there unfortunately are no AIS targets 2000 meters above sea level and 600km from the nearest shore where I sit, no matter if it's winter or not
BTW, if there's anybody in a similarly busy area on the southern hemisphere, I don't mind having the data from there...

Pavel

[bcn]

Dropping a mail to Comar? They are there and will have for sure a lot of data.

[Nicholson58]

We have Watchmate 850 with the antenna on the main at 80 feet. We see class A at up to 80 miles. Class B probably around 5 to 10 miles.

Consider that the Class A may be pretty fast. The local ferry to Milwaukee is over 40 knots. The Class B vessels are typically 0 - 15 knots. 5 miles is just fine. It has also been my experience that the CG and MIB see us a long way out - more than 10 miles.

That said, if there is boat to boat contact, it won't matter it its an A or B. We can filter based on parameters such as anchored or no calculated approach point. Any consideration of filtering based on class rather than hazard would be nuts.

[roundm]

well if you do pick up any targets I'd be more than a little concerned

I'll have a play with VDR and see if I can find enough cold boats for it to be interesting. I will comment that a few years ago I was playing with early versions of SOB and they'd implemented a maximum number of targets.

In the meantime - I don't know if this will work but.......

I have a copy of inavx on my ipad - I can get an email of the AIS NMEA datastream from that if I look out of the window and think it looks busy - would that be any use ? (I've just had a look and although it's 11pm there are still 20 commercial boats within about 20miles of me nothing like what I described but still for 11pm on a winter sunday night ) I can get this without going to my boat (meaning I'll have more opportunities to capture the data). Is that likely to provide what you'd like to see ?

Mark

[nohal]

Mark...
The busiest I have is http://www.navmonpc.com/Downloads/Pa...12%20Start.zip (will help you a lot in playing with VDR to see what it does) - Still not motivating enough to implement more filtering than I already did, so get me something even more crowded.

Pavel