Ais alarms repeatedly in big seas

[wholybee]

I would like to see an "acknowledge and mute" for a target, that would mute the target for a specific time. I could either set that time myself, or it could default to the time of the CPA.

For example, if a target has a CPA of 22 minutes, the mute would last 22 minutes. That way, if I come across the same vessel later in the day, it won't still be muted. As an option, if I think the CPA might close and become something I am concerned about, I could manually set the mute to last whatever time I want (perhaps 15 minutes), so that it will be muted while at a distance, but when it gets close if there is still a change of collision notify me again.

It would also be nice to be able to "acknowledge and change the CPA distance" for a single target. So, my alarm distance could be set to 5nm (which is what I usually set while in the ocean), and if the alarm goes off, I could set it for just that target to 0.5nm.

[karkauai]

I was crossing the Gulf Stream near Key west a few years ago. 30min after watch change. I CKD the radar and AIS, and saw a new target 10nm away CPA 5 nm. I went below to pee and start some coffee, then after 15 min started up the companionway a loud air horn sounded, like it was in the boat.. With my foot on the last step I leapt into the cockpit to see a massive freighter bearing down on me 200-300 yards away.. I stabbed the autopilot to standby and swung the wheel hard to starboard and managed to be only 25-30 yards away as it passed.
Lesson 1: they don't see you whether you have radar reflector or AIS or not
.After I changed my britches, I looked at AIS again and he was making 21kts. I was making 7.5kts, so we were closing at nearly 30kts.
Lesson 2:. If there's anything on AIS or radar, watch it long enough to know what it's doing before you go below. I insist on checking the horizon every 10 minutes, no matter what the circumstances. /
I had muted the AIS alarm because of repeated alarms earlier. Never again. Ships change course, don't look for you, and don't see you.

I hope you never experience anything like what I did. .I was just lucky he saw me at the last second.

[RogerLloyd]

I have AIS (receive only) Standard Horizon Matrix GX2100. I like it, BUT: When it warns me of a new target, I acknowledge it, then it loosest the target and then finds it again and alarms again. This can happen repeatedly, I presume at the maximum range of reception. I would have thought that it might keep an internal memory, but no !

Another problem is that when I get too many alarms I wish to turn off the alarm capability, but I cannot, because every time I get an alarm it removes my current screen and displays another screen ! I have tried to inform Stanard Horizon about the problem, but they do not seem interested. The later Matrix version still has the same problem, I am told, (so I will not update my hardware to that).

Any suggestions ?

[wholybee]

Originally Posted by RogerLloyd

I have AIS (receive only) Standard Horizon Matrix GX2100. I like it, BUT: When it warns me of a new target, I acknowledge it, then it loosest the target and then finds it again and alarms again. This can happen repeatedly, I presume at the maximum range of reception. I would have thought that it might keep an internal memory, but no !

Another problem is that when I get too many alarms I wish to turn off the alarm capability, but I cannot, because every time I get an alarm it removes my current screen and displays another screen ! I have tried to inform Stanard Horizon about the problem, but they do not seem interested. The later Matrix version still has the same problem, I am told, (so I will not update my hardware to that).

Any suggestions ?

Same radio, same AIS complaints. The DSC functions are abysmal as well. You get an alert, with a "Press any key" message. You press a key, and it goes right back to the home screen. Then you need to dig through menus and logs to find out what the alert was. God forbid it might be an important message. If it is an MOB because I fell overboard, I am toast, average crew will never figure it out.

If you have access to a boat show, showing them the problem, in front of a line of potential buyers, might push them to fix it. They have a Facebook page, but the last post was October of last year. They certainly don't seem very interested in feedback or communicating with customers.

[rwidman]

Shortly after installing my AIS transceiver, I determined that the audible alarms were annoying and turned them off.

However, I (or my wife) is always at the helm, operating the boat and paying attention. I can see the targets on the screen and the collision warnings and of course, I can usually see the other vessels with my eyes.

[wingssail]

Originally Posted by RogerLloyd

I have AIS (receive only) Standard Horizon Matrix GX2100. I like it, BUT: When it warns me of a new target, I acknowledge it, then it loosest the target and then finds it again and alarms again. This can happen repeatedly, I presume at the maximum range of reception. I would have thought that it might keep an internal memory, but no !

Another problem is that when I get too many alarms I wish to turn off the alarm capability, but I cannot, because every time I get an alarm it removes my current screen and displays another screen ! I have tried to inform Stanard Horizon about the problem, but they do not seem interested. The later Matrix version still has the same problem, I am told, (so I will not update my hardware to that).

Any suggestions ?

It is even worse on my version of Matrix 2000. The TCPA and CPA Alarm settings are independent and illogical. Let's say you set the CPA alarm distance at 1nm. A vessel overtaking behind which would reach you in, say, three hours, but, since it has a CPA of 50 meters, the alarm goes off, for a problem three hours away!

If you set a TCPA alarm for 5 minutes then any vessel whose TCPA is within 5 minutes sets off the alarm even though the closest it may get to you is 10 miles. Because that closest point is going to happen within the time you established, ALARM regardless of the distance.

And the difficulty of killing the alarm so you can talk to the approaching vessel (in the event of repeating alarms for a rapidly closing vessel) makes this dangerous.

At least OpenCPN and Vesper and maybe some others add the logic so you can define the alarm to be, "any vessel which will .5 miles within in the next 20 minutes"

Do I have any suggestions? Yes, buy a different brand radio (after checking how their logic works). In the meantime use OpenCPN for your AIS alarms.

[Scorpius]

I too LOVE OpenCPN!

However, the described problem is very real. Yesterday we were following another sailboat with AIS who actually turned it off (I spoke with him on the radio) as we very slowly caught up with him from behind (0.2 knot speed differential) and FINALLY came within his guard zone.

As an IT professional for some 40 years, very used to speccing systems I can certainly sympathize with both the users and developers on this one. However, I have some ideas:

1. Have different guard zone parameters (time and distance) for class A and class B targets. Class A targets are usually the big ships that we REALLY have to worry about. Class B are usually smaller, more manoeuvrable vessels that are less of a concern.

2. Keep track of "acknowledgements" by target anf halve the guard zone parameters for that target after it has been first acknowledged.

Icing on the cake would be for the system, for class B targets, to distinguish between those we REALLY have to worry about (the CPA is off to starboard and hence we are the "give way" vessel vs where it is to port or astern where we are the "stand-on" vessel. Maybe by colour: reserve red for those that are stand on relative to us and yellow for those that are give way. However ALL class A's that have a CPA within our guard zone should be in red and (an afterthought) a larger, distinctive, on-screen symbol to distinguish them from the class B's.

Keep up the great work guys (the developers). We really, really appreciate it!

[waterman46]

The false alarms are caused by course changes as detected by GPS position and not averaged over enough time. This is common to all digital instruments and is a pet peeve of mine. But don't expect manufacturers to be actual users, so no relief is in sight.

I use the alarms in the open ocean, and turn them off in traffic areas. Does anyone really want to do no lookout for more than 5 minutes in traffic?

[wholybee]

A workaround, I don't mute the alarm, but change the settings. I may change the CPA to very close, so it is "muted", but I'll be warned if it closes even closer, and if I forget to set it back at least I don't have no alarm.

OpenCPN has much better parameters for the alarm, but my laptop isn't nearly loud enough for AIS alarms. I also like to turn it off in the middle of the ocean to conserve power.

[wingssail]

Originally Posted by wholybee

...OpenCPN has much better parameters for the alarm, but my laptop isn't nearly loud enough for AIS alarms. I also like to turn it off in the middle of the ocean to conserve power.

Our laptop is mounted near the car stereo we use for music and the audio output from the laptop goes into the aux jack on the stereo. Believe me it is loud enough. (It also is how we play music and listen to the sound track when we play movies or TV shows).

We changed the alarm sound to really wake us up.

We too wanted to turn off the laptop during ocean crossings to conserve power, so we bought the Standard Horizon Matrix radio which uses much less power.

Unfortunately the Standard Horizon's AIS alarm system is so bad we can barely get any use out of it.

https://youtu.be/SbaeR-2BBfI

[rgleason]

Please see Flyspray Item #807
https://opencpn.org/flyspray/index.p...ls&task_id=807

Dave has made changes and marked this solved on 3/19/21
We would be very interested if these changes have helped get to the Acknowledge button in time!