Four vessels were built for rotation, with 2 vessels being deployed to Hong Kong at a time. The fifth vessel has been involved in two navigation incidents. The first time in 2001 whilst on a pre-delivery test it was nearly sunk after a crash with a fast ferry servicing the Hong Kong-Guangzhou route. In June 2006, it crashed again, this time with a Chinese freighter, and sank immediately, 13 servicemen going missing in the accident. The vessel was later refloated and sent to the shipyard for repair.