USCGC Storis (WAGB-21) is a United States Coast Guard medium icebreaker. She was originally built as the icebreaking anchor handling tug supply vessel (AHTS) Aiviq to support oil exploration and drilling in the Chukchi Sea off Alaska. The USCG acquired the vessel in December 2024 and she was commissioned in Juneau on 10 August 2025.
General characteristics Storis is long overall and between perpendiculars. Her hull has a beam of and depth of . Fully laden, she draws of water.Shell Takes Delivery of New Ice Class Vessel . Shell, 24 March 2012. Built as an anchor handling tug and supply vessel, Storis was originally fitted with a large towing winch located amidships as well as chain lockers and storage tanks for both liquid and dry bulk cargo under the main deck.Appendix K: Ice management plan . Shell Offshore Inc. Pages 41–43. Her gross tonnage is 12,892, net tonnage 3,867 and deadweight tonnage 4,129 tonnes.
Storis is powered by four 12-cylinder Caterpillar C280-12 four stroke medium speed diesel engines, each producing at 1,000 rpm. The engines are coupled to two Schottel controllable-pitch propeller in nozzles via Flender reduction gearboxes.Aiviq: Pride of Shell's Alaskan drilling fleet. Professional Mariner, 16 October 2012. The propulsion system gives Storis a service speed of in open water and in level ice, and a bollard pull of 200 metric tons. She also has two 2,000 kW shaft generators and four 1,700 kW Caterpillar 3512C auxiliary diesel generators that provide power for onboard consumers, including the firefighting system. She has three bow thrusters, one of them of azimuthing fold-down type, and two stern thrusters that give her dynamic positioning capability. For redundancy and improved handling, she has two high-lift rudders.Breaking the Ice . WorkBoat.com, 15 May 2012. The propellers of Storis were reportedly designed to be quieter than normal in order to be less disruptive to local marine life.
Storis was built to American Bureau of Shipping ice class ABS A3 which indicates that she is strengthened for navigation in polar ice conditions with the presence of multiyear ice floes. Furthermore, the notation "Ice Breaker" states that she is designed and constructed for breaking ice to open navigable channels for other ships.
Construction
In July 2009, Edison Chouest Offshore won a $150 million contract for the construction of an icebreaking anchor handling tug supply (AHTS) vessel for Royal Dutch Shell. The vessel, largest ever built by the company, would be used to support Shell's drilling operations in the Beaufort Sea and Chukchi Sea off Alaska.Chouest scores new icebreaker contract . dailycomet.com, 22 July 2009. In January 2010, it was announced that the vessel would be constructed in Louisiana. The hull and the superstructure would be built in the company's own shipyard North American Shipbuilding Company in Larose in two separate units while the final assembly of the vessel would take place at LaShip, also owned by Edison Chouest, in Houma. In all, the construction would take just over two years and provide work for about 800 people.Icebreaker to be built locally. dailycomet.com, 22 January 2010.
Laid down on 3 February 2010, the newbuilding "Hull 247" was presented to Shell executives on 30 September 2011. By then, the price of the vessel had climbed to $200 million due to material and equipment factors, such as the price of steel.Shell execs get glimpse of 'all new' icebreaker ship design . WWLTV, 1 October 2011. Shell hopes to break the ice on Arctic drilling. Chron, 30 September 2011. The vessel was launched on 1 November 2011. According to Edison Chouest spokesman Gary Chouest, "It [Aiviq] will be the world's largest and most powerful anchor-handling icebreaker." The vessel has also been called the world's most powerful privately owned icebreaker.
In 2011, Shell invited Inupiak schoolchildren to submit essays suggesting names for the vessel. Twelve-year-old Elizabeth Itta submitted the winning essay, describing how the Walrus, "Aiviq" in the Inupiak language, use their tusks to break ice. She won a cash prize for her school and an invitation to attend the ship's launching ceremony on 24 March 2012. ()USA: Edison Chouest Offshore Shipyard Christens Shell's New Icebreaker Aiviq . ShipbuildingTribune.com, 26 March 2012. The vessel went for sea trials in April and was delivered on 20 April 2012.Giant ice-class AHTS on sea trials following completion by Chouest . MarineLog, 1 April 2012.
The construction of the new icebreaker and Shell's Arctic drilling operation off Alaska raised concerns about the ability of the United States Coast Guard to operate in ice-infested waters since at the time the Coast Guard had only one operational icebreaker, .Shell-Led Arctic Push Finds U.S. Shy in Icebreakers: Energy. Bloomberg BusinessWeek, 18 July 2012.
In April 2015, it was reported that Edison Chouest would build two Polar Class 3 anchor-handling tug supply (AHTS) vessels at the company's LaShip shipyard in Houma, Louisiana. Unlike Aiviq, the new vessels would have been fitted with Rolls-Royce azimuth thrusters instead of conventional shaftlines and rudders.Rolls-Royce to supply propulsion and deck machinery to a new vessel for Edison Chouest . Rolls-Royce, 4 March 2015. However, in November 2015 it was reported that Edison Chouest might have canceled the vessels following Shell's decision to halt Arctic oil exploration.Chouest said to have canceled Arctic AHTS duo. MarineLog, 9 November 2015.
Career
Aiviq (2012–2024)
2012 grounding of Kulluk
On 27 December 2012, while Aiviq was towing the mobile offshore drilling unit Kulluk off the coast of Kodiak Island, Alaska, the towing line between the icebreaker and the drilling rig parted due to a mechanical failure of the towing shackle.M/V Aiviq Tow-Gulf of Alaska . Alaska Department of Environmental Conservation, 28 December 2012. Shortly after the tow had been regained, the main engines of Aiviq failed and the vessel lost propulsion power in seas. In the following morning, power was successfully restored on one of the four main engines and the vessel was able to hold position in the heavy weather.MV Aiviq loses power at sea. Aiviq Tow - Gulf of Alaska, Unified Command, 28 December 2012. United States Coast Guard cutter USCGC Alex Haley was dispatched to the scene to monitor the situation.Coast Guard assists tug and tow in Gulf of Alaska . United States Coast Guard, 28 December 2012. In response to the incident, the Coast Guard, Shell and Edison Chouest established a Unified Command to coordinate the operation.Unified Command established. Unified Command, 28 December 2012. Shell-contracted vessels Guardsman and Nanuq were also en route to the scene.
On 29 December, the Unified Command authorized the drilling rig to drop its anchor to slow its drift towards the coast and ordered the Coast Guard to evacuate the 18 crew members on Kulluk by helicopter as a precaution.Unified Command Statement #3. Unified Command, 29 December 2012. Unified Command authorizes Kulluk to drop anchor to slow drift. Unified Command, 29 December 2012. Sikorsky HH-60 Jayhawk helicopters operated by the Coast Guard also delivered essential equipment parts to Aiviq and later power was restored on all four engines. Together with Nanuq, Aiviq was able to hold the drilling rig stationary during the crew evacuation and later continue towing the vessel away from the coast.Incident response continues, second engine running on Aiviq. Unified Command, 29 December 2012. Update #6: 18 personnel on Kulluk safely evacuated, Aiviq's 4 engines functioning. Unified Command, 29 December 2012.
On 30 December, the tow lines of Aiviq and Nanuq parted again, and Kulluk began drifting towards the coast. Another tugboat, the 10,000-horsepower Alert operated by Crowley Marine Services,Alert. Tugboat-information.com. also arrived to the scene from Prince William Sound.Update #9: Kulluk tow lines separated; Alert on scene. Unified Command, 30 December 2012. Shortly after midnight, Alert was able to secure connection to the towing line previously used by Aiviq and later in the morning the icebreaker had also reconnected to Kulluk about southeast from Kodiak Island.Update #10: Kulluk under tow by Aiviq and Alert. Unified Command, 31 December 2012. USCGC Alex Haley also returned to the scene from Kodiak, where the cutter had repaired her fouled port propeller, and relieved the crew of USCGC Spar as on scene commander. The helicopter crews were also preparing to deploy several technicians aboard the drilling rig to evaluate the condition of the towing lines.Coast Guard crews continue battling fierce storm to assist Kulluk near Kodiak, Alaska . United States Coast Guard, 31 December 2012.
Later in the evening, Kulluk was again set adrift after the Coast Guard ordered Alert to separate from the rig, now only from the nearest point of land, to maintain the safety of the nine crew members on board the tug in nearly seas.Kulluk is adrift; four miles from nearest point of land. Unified Command, 31 December 2012. Only moments later, Kulluk was grounded near the uninhabited Sitkalidak Island at a depth of about .Unified Command Update #12: Kulluk grounded, vessel condition not yet confirmed. Unified Command, 31 December 2012.
The salvage operation was awarded to the Dutch salvage company Smit International.. Unified Command, 2 January 2013. A team of five salvage experts boarded Kulluk on 2 January 2013 to assess the structural integrity of the grounded drilling barge. On 3 January, it was reported that Kulluk had suffered damage since the grounding but its structural integrity had not been compromised and there have been no leaks from the rig's fuel tanks.Kulluk Has Suffered Damage Since Grounding, Hasn't Leaked Oil . KTUU.com, 3 January 2012. At the time of the grounding, Kulluk was carrying 139,000 gallons of diesel fuel and 12,000 gallons of lubricating and hydraulic oil.Unified Command Update #13. Unified Command, 1 January 2013. By 4 January, 14 vessels had been mobilized for the recovery operation and the United States Department of Defense provided two Boeing CH-47 Chinook helicopters to transport heavy salvage gear to the site.
Kulluk was successfully refloated on 6 January and towed to a sheltered location in Kiliuda Bay, some from the original grounding location, on the following day.. Unified Command, 7 January 2013. After the rig was brought to a shipyard in Singapore on board a heavy-lift vessel, Shell decided not to repair the damages and sold the drilling unit for recycling in China.Shell responds to BOEM. Petroleum News, 5 January 2014.
In the investigation report published by the United States Coast Guard on 2 April 2014, the initiating event to the casualty was identified as the failure of a 120-ton apex shackle which was considered undersized for towing Kulluk in such environmental conditions. The 90-feet catenary surge chain used to damp shock loads in the towing line was also deemed insufficient. According to the Coast Guard, the "numerous and compounding preconditions" that led to the casualty also included various operational issues such as the towing plans that were not adequate for the winter towing operation crossing the Gulf of Alaska and the crew's lack of towing experience in the Gulf of Alaska waters particularly during the wintertime.Report of Investigation into the Circumstances Surrounding the Multiple Related Marine Casualties and Grounding of the MODU KULLUK on December 31, 2012. United States Coast Guard, 2 April 2014.