Monitoring published on BlackSeaNews website began on 14 March 2014 and covered 9 Crimean ports: Eupatoria, Sevastopol (two), Yalta, Feodosia and Kerch (four). It's an ongoing everyday monitoring.
Only passenger and trade vehicles who enter and leave Crimean ports are blacklisted. The vessels that belong to Crimean fleet are not subject to sanctions (according to Ukrainian officials the vessels nationalised by Russia are still the property of Ukraine), as well as yachts, fishing boats docked in Crimea since before the annexation, belonging to locals.
Vessels who took cover from bad weather conditions and sent signals from Crimean ports while in reality stationed near the coast or on roadstead, are also not blacklisted.
The fact that foreign freighters reregister their vessels to fictional owners in order to go around the sanctions is a major problem for the experts.
In order to monitor vessels entering the Crimean ports, AIS Automatic Identification System is used. Transmitters installed onboard send signals which specify positions of vessels and allow identification. All ships with tonnage exceeding 300 and making international cruises are obliged to have AIS transmitters installed. However, some crews decide to turn them off.
Ukrainian experts that monitor sea connections with Crimea mainly use the software support of ShippingExplorer Ltd., but acquired data is also verified by other sea services dedicated to spreading information about AIS signals sent from ships.
Ukrainian 'black list' includes ships that breached the sanctions under flags of 32 countries and entered Crimean ports.
Full list of blacklisted vessels can be found below: