I can see the ships in Holland!

[oilybilge]

I just installed a new deck connector and coax for my VHF/AIS, and when I fired up navionics just now I could see the ships approaching Rotterdam from my buoy on the Alde. How is this even possible?! It must be eighty miles at least. Is it witchcraft?

It does go to show, though, the old coax was only four years old, but in the exposed section between mast and deck plug the braid was completely corroded and crumbled away. Previously I could barely see ships ten miles away.

 

[johnalison]

I would normally see around 40 miles over water but with the high pressure around lately something like 80 miles seems entirely possible and I’m sure I have seen similar at times, even with a splitter!

 

[Daverw]

atmospheric conditions with the high pressure system we've just had, unfortunately not reliable fir comms use but much fun for ham radio operators

 

[AngusMcDoon]

How is this even possible?! It must be eighty miles at least. Is it witchcraft?

Atmospheric duct - Wikipedia

 

[johnalison]

Some years ago we had just left Ramsgate when we heard a club mate on the VHF as clear as anything, so we called them up. It turned out that they were still in the Blackwater and we managed to have a conversation without any breaks. This was at least double the predicted yacht to yacht range. I was fun in ye olden days to play with the Decca set and try to get a fix from distant chains. I think I got a fix from Northumberland once with an error of only about five miles.

 

[MoodySabre]

I don't mind seeing ships but listening to Ostend Radio is a bit tedious.

 

[oldvarnish]

When you start seeing vessel at huge ranges, there's usually something like this in the chain
PMAPI AtonisPro-R AIS Repeater

 

[Bilgediver]

I just installed a new deck connector and coax for my VHF/AIS, and when I fired up navionics just now I could see the ships approaching Rotterdam from my buoy on the Alde. How is this even possible?! It must be eighty miles at least. Is it witchcraft?

It does go to show, though, the old coax was only four years old, but in the exposed section between mast and deck plug the braid was completely corroded and crumbled away. Previously I could barely see ships ten miles away.

Freak conditions. Here in Edinburgh I was seeing similar Ham transmissions (APRS) from about 10 vehicles driving around in Norway between Stavanger and Bergen. Like AIS their transmissions include Lat. Long. I believe APRS protocol was used in AIS'

The ham transmissions might have got some help from a repeater at Rogoland though no indication that this happened.

 

[KompetentKrew]

When testing out my new AIS earlier this year I received AIS messages 300nm away (after taking the below screenshot showing 250nm).

Note all the ships shown are in the same direction, in a 30° or 40° cone - there must be ships to the west of this location, sailing up the Portuguese coast, but they're not shown at all.

I believe there was a high pressure system nearby at the time, and I also figured that maybe the radio signals had bounced off the water on the way here, hence why I'm not seeing them where there's land in between.

 

[C08]

I have also seen ais targets in the straits of Gibraltar from wales

 

[oldvarnish]

As I posted earlier, it's possible that you are not receiving the signal directly from the source (ship) but via a repeater which might be much closer to you.

 

[KompetentKrew]

As I posted earlier, it's possible that you are not receiving the signal directly from the source (ship) but via a repeater which might be much closer to you.

Would this show in the NMEA sentences passed along by the AIS receiver, please?