Sea Patrol is an Australian television drama that ran from 2007 to 2011, set on board HMAS Hammersley, a fictional patrol boat of the Royal Australian Navy. The series focuses on the ship and the lives of its crew members. Despite similarities in setting and content, this series is not a follow-on to the 1979 series, Patrol Boat. At the start of the second season, Sea Patrol saw an upgrade from the Fremantle class to a newer Armidale class boat. The first season debuted on 5 July 2007 on the Nine Network, who invested $15 million into the programme. The second season of Sea Patrol, titled Sea Patrol II: The Coup, aired in 2008, while the third season, Sea Patrol: Red Gold, aired in 2009. The fourth season aired in 2010 in a new 16-episode format, with no main theme or continuous storyline running throughout, unlike the first three seasons. The fifth season of Sea Patrol, "Damage Control", began airing in 2011 and consisted of 13 episodes. The Nine Network has confirmed that this was to be the final season, due to reliance on government rebates that expire after 65 episodes. Completion of series five brings the total episode count to 68 episodes.