Investigate the daily broadcast warnings at
http://www.nga.mil/portal/site/maritime/
sometimes you can read things like this:
MALAYSIA: An unidentified tug and barge are reported missing 21 May (reported 8 Jun) while enroute Port Klang from Kuala Beram, Miri, Sarawak with a cargo of scrap metal. The IMB reports suspicion that crew may have hijacked the vessel (IMB).
SOUTH CHINA SEA: Unidentified product tanker was boarded 31 May at 0225 local time while underway in position 01 32N, 104 38E by 2 persons who entered engine room and broke into stores. Duty engineer raised alarm and the two jumped overboard and escaped (IMB).