Obreid
The ships will be ghosts only near the coast and inshore where the data is harvested by shore based receivers........unless they do something to either disrupt GPS and GLONASS or disrupt the link frequencies to the satellites for the sat ais targets, then I dont think they can do much more. Also bear in mind that the sat-ais targets can be seen in more detail with a subscription to the AIS system by users. The shore harvested ais data is free of charge. The satellite harvested data is subscription only, for example this link
MarineTraffic Live Ships Map. Discover information and vessel positions for vessels around the world. Search the MarineTraffic ships database of more than 550000 active and decommissioned vessels. Search for popular ships globally. Find locations of ports and ships using the near Real Time ships...
www.marinetraffic.com
shows another map of AIS data as was with ships now but for sat data this is their subscription page
MarineTraffic Online Services. Simple, powerful and effective tools tailored to your needs. MarineTraffic Online Services enable you to monitor, review, analyse and plan shipping operations. Whether you need information for a vessel, a port or at the global level, there’s a service to match your...
www.marinetraffic.com
as from observation on either shipsnow or marinetraffic websites you see that the ships along the coast of China that were before the purview of shore based ais receivers are still visible but with the sat notation...and with a subscription to the sat based system on marinetraffic, would still be visible despite what China has done.....
Riffraff
I think that the shore based ais disruption is a created nuisance nothing more. Far as the ais relation to the rumored Chinese conversion of merchies to use as dual purpose vessels I dont think there is much association there. Bear in mind all that has to be done is the ship master deciding to switch the ais off or being told to switch ais off. Then its invisible to either satellite or shore based systems and....much like a plane with the transponder switched off, the only way it can be found is either visually or skin painting it with radar or sonar. It will be impossible to see dual use or military ships if their ais transponders are switched off, subscription service or not. When i said it will make it more difficult for us to see possible dual use ships I only speak of myself and whomever else here tries to look at marine traffic as a possible indicator of military preparations. I think that if for example, a modified container ship or ro ro is dockside being loaded in support of a military move then they are going to have their ais transponders switched off. Consider this-- before China switched shoreside ais off--if you watched traffic in an area enough to be familiar with what ships frequented an area then if a ship docked at a different pier or harbor it would stand out. Ships for the most part have regular ports of call and many of them will dock at the same location in each harbor each time they visit. Now the low hanging fruit part of that intel has disappeared unless you are a subscriber and with a simple word from either the ship captain or shore authorities to shut ais off then the rest of the ais provided intel will be gone as well. Could China set up jammer stations to kill ais along the China coast and across the strait into Taiwan- I think that possible. Such a move would be as provocative as jamming GPS/GLONASS.
For those interested in more there is this page
en.wikipedia.org
Regards