Well this is a new one for me..

Sailing in an unfamiliar area to me, and I am heading for a marked channel were I am expecting to see 3 pair of channel markers as seen on Navionics. Everything is making sense (I wasn't totally unfamiliar with the area but it had been probably 5 years since I was last in it) and my AIS was going nuts flashing red indicating that expected channel markers were within my preset 'danger zone'. Nothing new, a lot of the markers around Fremantle and into Cockburn Sound have AIS returns associated with them.

But for the life of me though I couldn't see these markers, and we should've just about run into them. I asked 2 others onboard if they could have a good look too, but nup nothing around. Pulled out the official chart and the channel I was suppose to be in had the marks labeled V-AIS or very basically Virtual AIS, except the AIS signal is from an off location source. There simply is noting physically there.

The future is going to be an awesome place and one day people are going to look back at our era and think we are just as basic as our era views the likes of Christopher Columbus.

That is interesting Toph. First time I have heard of it.
@ gary, remember when that was what everyone said about GPS early in the piece? What if the yanks go to war and switch it off?
Well they have gone to war since and not switched it off and the system has only got better.
I think the main worry is on board systems failure rather than anything else.
However I do like to be able to use the tried and true methods using your eyeballs, compass, charts, parallel rules and pencils.

the capability of deliberately degrading the performance was built-in to the GPS system:

www.gps.gov/systems/gps/modernization/sa/

the Selective Availability capability is deprecated now, but of course the military have developed other ways to interfere with GPS systems (it is just radio signals after all)...

maritime-executive.com/blog/ecdis-what-happens-when-the-gps-signal-goes-away

Not a bad idea for places like Cockburn where there is only one busy narrow shipping channel and lots of very shallow water around. Encourage recreational boats to use the virtual channel.

That is way cool.
Do you know how it works Toph?
That seems pretty amazing.
Be nice to verify race course turning marks with AIS.

Hi Gary,

You are right in that I "stumble across it". As I said, I was expecting to see port and starboard bouys and my AIS was indicating they were there, but they weren't. I did to a web search before I posted the original post. I should've added a link then. I'm working this morning but I'll do another search and post some links

By all means repost elsewhere though and see what answers you can get. But for a technology advances country such as Japan, I'm surprised they don't know let alone not believe you....

In any case, I plan on going for a sail tomorrow and will be going straight past these marks so I try and get some video of it all..

Here you go Gary.. An explanation from the NOAA website
nauticalcharts.noaa.gov/publications/portrayal-of-ais-aids-to-navigation.html

"Virtual AIS ATON - An aid to navigation with no physical structure. It exists only through AIS mssages broadcast from another location. A few uses of virtual ATONs include environments where buoys are moved seasonally, such as in sea ice, or where a marker needs to be placed quickly, such as to mark a newly identified isolated danger or wreck. These aids can only be seen on an Electronic Chart Display and Information System (ECDIS), or other AIS enabled display, such as a ship's radar"