AIS600 vs Marine Traffic info

B

billrh42

Active member
Joined
Sep 10, 2023
Messages
31
Fluid Motion Model
R-29 Classic
Hull Identification Number
Fmlt2928c010
Vessel Name
Spirited Away
I have a new to me 2010 R29 classic with a 2010 AIS 600 linked to a Garmin 5215 chartplotter. I'm wondering if my AIS unit is not working correctly. When looking at MarineTraffic for the harbor the boat is at I can see 10 or so class B AIS signals. When looking at my chartplotter, one day I only saw about half those boats and a few days ago I didn't see any at all. In both cases I left the chartplotter on for about 10 minutes.
The AIS is transmitting my AIS signal as I can see it on MarineTraffic but it doesn't seem to be receiving the other boats.

Any thoughts as to what might be causing this?

-Bill
 
How far away are the boats you see on MarineTraffic? The ground-based receivers that are used for MarineTraffic and the like are going to be much better (both in size and visibility/location) than your VHF antenna on your boat.

My guess is that since it works sometimes but not other times, it's simply a signal quality issue.
 
watson1987":203aksva said:
How far away are the boats you see on MarineTraffic? The ground-based receivers that are used for MarineTraffic and the like are going to be much better (both in size and visibility/location) than your VHF antenna on your boat.

My guess is that since it works sometimes but not other times, it's simply a signal quality issue.
Click to expand...

Agree. Look at a target you see on Marine Traffic but not on your chart plotter. When you click on that target it will give a time received and from which station. Click on the station and it will give the station location and elevation.
 
Thee of the boats that show up on Marinetraffic but not my AIS are about 30' behind me in the next slip. So they are pretty close.

I'm beginning to wonder if my antenna cable/connections need to be checked. I'll add that to the next trip to the boat.

-Bill
 
It might not be the case, but most Garmin units going back to the 52** generation have some form of AIS filtering available. If I recall the 52** series has a range based display option on the charts/radar in the menu listed as "other vessels".

In the system there should also be a list form of other vessels which will simply list all vessels that your AIS unit is seeing without any filtering applied.
 
Full_O_Fish":339q30hx said:
It might not be the case, but most Garmin units going back to the 52** generation have some form of AIS filtering available. If I recall the 52** series has a range based display option on the charts/radar in the menu listed as "other vessels".

In the system there should also be a list form of other vessels which will simply list all vessels that your AIS unit is seeing without any filtering applied.
Click to expand...

Here's the section from the 5200 series manual (I have the 5215 with an AIS 600). You can set the range in which you see targets displayed on the chart plotter.

53564117907_1908fdc14c_w.jpg
 
I visited the boat today and double checked the settings in the chart plotter. They were all ok. I still want to do a SWR check too.
Today I was getting 4 targets within the harbor from my chart plotter compared to about 10 on Marine Traffic. As I looked around the harbor I realized the the four targets that my chart plotter is picking up is visible to my eye and the others are hidden behind larger boats. So I'm now thinking that their signals are being blocked. We plan to finally take the boar out for its first cruise in a week or so and I'm hoping that the other boats show up once we start moving around.

Crossing my fingers.
-Bill
 
Another possibility is that the difference is data persistence.

I believe Marine traffic and other such sites report the last position found. It persists for some time if no new data is received (I think at least 24 hours). The targets you are seeing on Marine Traffic have likely shut off their AIS in last 24 hours.

Your Garmin is real time data, it only shows targets that are there signaling within a very narrow window of time (2 seconds to 3 minutes depending on boat type and status). It what’s there right now.

Curt
 
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