Stalwart-class ships were designed to collect underwater acoustical data in support of Cold Waranti-submarine warfare operations. Accordingly, Indomitable employed Surveillance Towed Array Sensor System equipment on Cold War underwater surveillance duties during the final years of the Cold War. After the Cold War ended with the collapse of the Soviet Union in late December 1991, requirements for such surveillance declined. In 1993, Indomitables SURTASS gear was removed, and she received an AN/SPS-49 radar for use in counternarcotics surveillance. In her new role for counter narcotics patrol she deployed for two missions per year starting September 1993. As well as her civilian crew, she embarked 18 Navy personnel to operate her sensors and coordinate with authorities. For her first five missions she averaged 300 days underway per year operating in the Caribbean Sea and Panama Canal area. Due to her extended at Sea times, she operated a Civilian Ham Radio station from 1994-1995 for the crew to maintain contact with their families. Stateside operators freely cooperated making long-distance calls for the grateful crew. The Navy retired Indomitable from service on 2 December 2002 and struck her from the Naval Vessel Register the same day.
National Oceanic and Atmospheric Administration service
On 9 December 2002, Indomitable was transferred to the National Oceanic and Atmospheric Administration. NOAA converted her into an oceanographicresearch ship. She was commissioned in the NOAA fleet as NOAAS McArthur II on 20 May 2003, replacing the NOAA survey ship NOAAS McArthur, which was decommissioned the same day in a combined ceremony.
Capabilities
McArthur II has berthing for 38 people in 18 single staterooms, eight double staterooms, and one quadruple stateroom, providing her with the capacity to carry up to 15 scientists on domestic voyages or up to 14 scientists and a United States Public Health Service officer on international voyages. She can seat 16 people at a time in her crews mess. McArthur II has a wet laboratoryfreezer, a dry laboratory freezer, and an oceanographic laboratory refrigerator. On deck, she has a 2.3-ton-capacity deck crane with a boom that extends to 46 feet, two oceanographic winches, a movable A-frame, and a movable J-frame. She carries one 24-foot and one 21-foot Zodiacrigid-hulled inflatable boats.
Operations
McArthur II was an active member of the NOAA Pacific Fleet with her home port at Seattle, Washington. She departed Seattle on her maiden NOAA cruise on 1 June 2003. She conducted oceanographic research and assessments throughout the eastern Pacific Ocean, including along the United States West Coast - where she was involved in studies in several national marine sanctuaries - and the Pacific coast of Central America and South America. She engaged in measurements of chemical, meteorological, and biological sampling for several large-scale programs within NOAA, and the scientists who carry out research aboard her come from many divisions of NOAA, as well as other United States Government agencies, U.S. state government agencies, and academia. McArthur II was retired by NOAA on 18 June 2014. She had been inactive since 2011.
Caladan Oceanic LLC service
In 2017 the vessel was bought by Caladan Oceanic LLC and prepared to serve as a mother ship for the manned deep-ocean research submersible DSV Limiting Factor. The vessel was named DSSV Pressure Drop because the financial sponsor Victor Vescovo admires the ship names found in the Culture novels written by Iain M. Banks. Beginning in December 2018, the Pressure Drop began execution of the to support a manned submersible visit to the bottom of all five of the world's oceans. On December 19, 2018, the first of the five oceans bottoms was visited: the . In August 2019, the Pressure Drop completed the Five Deeps Expedition after the Limiting Factor submersible successfully made the first manned descent to the bottom of the Arctic Ocean, the Molloy Deep.
