AIS questions - new plotter

[doug748]

I am looking at buying a new plotter with AIS and trying to detect which ones would give me a positive indication if crossing targets will pass ahead or behind.
Raymarine software works this out with what they call Velocity Vectors, the software works them out and displays the dynamic situation in the following manner:

"The latest release of Raymarine chart plotter software (V15) has two new features for AIS.......
.........The second feature which is a major step forward is the addition of “predicted areas of danger”. The chart plotter will show a vector indicating direction of your vessel and one for a crossing vessel. It will then show and hatched red area ahead of the other vessel. If you vector passes through this area there is a collision risk. If it passes ahead of the area, then you will pass ahead. If astern of the area (not necessarily astern of the AIS target) then you will pass astern. This gives a great deal of useful information ....."

The question is:

1) Do you use this Raymarine system and if so, on what kit. How new is it (there is some fog around when it was introduced)?

2) Have you another system (hopefully cheaper) that does the same trick - ie show definitively if a target is ahead or behind at CPA?

.

 

[Martin_J]

I'm not up to date with the most modern potters, but OpenCPN, running on the boat computer has for many years shown both your own vessel predicted position and the predicted position of the other vessel at the CPA (Closest Point of Approach).

Perfectly easy to see if you're going to be ahead or behind the other vessel, updating constantly in real time.. Or if the CPA is zero, you can very quickly see how much separation a half a degree change in course will give you.

I'll be interested to hear which modern MFDs can do the same.

 

[dunedin]

The Navionics feature you refer to was introduced on Lighthouse 2 software - used on the (LOWER CASE) c & e-Series plotters with version 15.59 in Sept 2015
Works very well and use regularly. One of reasons for replacing older E-Series in at the helm with a newer e-Series bought on eBay

 

[westhinder]

It is a useful feature, although it is not always clear at first glance whether you will pass ahead or astern.
A drawback that I have encountered is that in areas with a lot of AIS targets, the red hatched zones clutter up the screen so that you might miss navigational details. I have tried but not found how to switch off those zones other than switching off AIS altogether.
Oh I use a Raymarine Axiom+, that otherwise I’m very pleased with.

 

[James_Calvert]

Don't have any plotter that gives such detail on screen.

But if I get my system to list the danger targets I can monitor their current bearing from me. If the bearing increases, it will pass one way, if it decreases, it will pass the other. If it's constant, we will collide.

Gives exactly the same information as a handbearing compass, but much more accurately and immediately.

Typically at around 2 miles distant, anything of concern will alter course to pass 0.5 mile ahead or astern.

 

[trevorr]

It is a useful feature, although it is not always clear at first glance whether you will pass ahead or astern.
A drawback that I have encountered is that in areas with a lot of AIS targets, the red hatched zones clutter up the screen so that you might miss navigational details. I have tried but not found how to switch off those zones other than switching off AIS altogether.
Oh I use a Raymarine Axiom+, that otherwise I’m very pleased with.

You need to toggle the AIS PAD button to remove the red boxes.

 

[MontyMariner]

Similar to James_C, I take note of the ships COG when the alarm first comes up, then check periodically for a COG change.
The direction of change tells me if it will pass forward or astern.

 

[john_morris_uk]

We use Raymarine Axiom and were very happy with it. 99% of the time I use the mk1 eyeball but if a ship/boat looks as though it might be passing close I go and look at the plotter and click on the target to get an instant CPA and TPA etc. . Another click or two and you get a whole raft of information about the target. (Name, where it’s come from, where it’s going etc etc).

Targets flash red if they are going to pass closer than a preset user chosen CPA.

 

[dunedin]

It is a useful feature, although it is not always clear at first glance whether you will pass ahead or astern.
.....

Actually that is the big benefit if the relative vectors - eg on the Raymarine version the OP refers to.
Just using a CPA doesn't tell you this. But the relative vector instantly shows if the target is crossing in front or ahead. Very useful.

Of course, when looking at CPA and vectors, very important to remember this is the position of the target AIS beacon. On a big ship the bow could be 300m ahead of this !!!

 

[requiem]

OpenCPN has an OK setup for AIS, particularly in its presentation of CPA for multiple targets (see first screenshot). I don't know if it also includes Bow Crossing Range, but BCR should be available on any decent system. (It simply tells you how far ahead (or astern) the other vessel will cross your bow, which is different from the CPA.)

What I much prefer to see are ticked course vectors: in this example the vectors are set to 12 minutes, so each tick represents one minute's travel, and one can get an idea of the crossing by simply seeing which ticks align when they cross. E.g. if both vectors are crossing at the 8 minute mark, that's not so good, but if the 2 minute mark of one crosses the 10 minute mark of the other then there's usually plenty of space.


In terms of relative vs true, I prefer relative vectors on the radar display and true vectors on the chart display.

 

[Roberto]

And when there are many

 

[johnalison]

You just need to bear in mind when using the Raymarine vectors that, as far as I remember, display the vector in relation to your vessel and not the other vessel’s course on the chart.

 

[Boathook]

And when there are many


View attachment 188313

My screen used to look like passing a marina or around the Solent. Turned off or reduced AIS settings to keep the screen readable. This is for a raymarine AIS and eS9 MFD

 

[Roberto]

My screen used to look like passing a marina or around the Solent. Turned off or reduced AIS settings to keep the screen readable. This is for a raymarine AIS and eS9 MFD

Yes that s with a very old version or OpenCpn, they have since improved the Ais display system one can configure several different settings to get a more useful representation.

 

[PeterV]

The Garmin plotters also show targets, CPA is shown green if astern, red if ahead.

 

[wonkywinch]

You can usually adjust the AIS settings to hide stationary traffic and/or stuff moving at less than x knots.

 

[doug748]

The Garmin plotters also show targets, CPA is shown green if astern, red if ahead.

Thanks, this looks to have promise, do you know which models?

I am not keen on spending 1500 quid ish on Raymarine or using Open CPN. Just want a simple plotter/transponder + this AIS feature

.

 

[Boathook]

You can usually adjust the AIS settings to hide stationary traffic and/or stuff moving at less than x knots.

Need to look for that on my MFD. Will sort out a lot of problems around the Solent.

 

[wonkywinch]

Need to look for that on my MFD. Will sort out a lot of problems around the Solent.

People seem to leave their AIS transponder powered 24hrs a day in the Solent. Even when on the hard. Hamble Point & Port Hamble as an example this morning ..

 

[PeterV]

My Garmin is a Garmin Echomap UHD65cv, connected to a McMurdo Smart Find M10 AIS.