VESSEL CONVERSION | USCGC Storis – Rebuilt anchor handler placed into service as coast guard icebreaker

The US Coast Guard recently began operating an icebreaker that has been converted from an Arctic-capable anchor handling and oil exploration vessel previously used in the offshore energy industry.

USCGC Storis is the former Aiviq, which, at the time of her acquisition by the coast guard in late 2024, had been operated by Edison Chouest Offshore and was the only US-built commercial vessel that met necessary icebreaking standards.

The vessel was acquired by the coast guard to provide near-term operational presence as a bridging strategy while the service’s new polar security cutters are under construction.

Heavy duty propulsion setup ideal for sustained ice navigation

In US Coast Guard service, the vessel was renamed Storis after an earlier coast guard icebreaker of the same name that had been in operation from World War II until her final decommissioning in 2007. The newer Storis has been classed as a medium polar icebreaker intended to expand US operational presence in the Arctic.

Originally built in 2012 in compliance with American Bureau of Shipping class requirements, Storis measures 360 by 80 feet (110 by 24 metres) and is powered by four Caterpillar C280-12 5,440hp (4,060kW) diesel engines that drive two Schottel controllable-pitch propellers housed in nozzles.

The propulsion arrangement delivers a top speed of 15 knots in open water and five knots in surface ice of up to 3.3 feet (one metre) thick as well as a bollard pull of 200 tonnes.

The vessel boasts two 2,000kW shaft generators, four Caterpillar 3512C auxiliary generators, three bow thrusters, and two stern thrusters. The bow and stern thrusters are used in conjunction with a dynamic positioning system to ensure improved station keeping.

The vessel has also retained her flight deck, which is compatible for use with the coast guard's MH-60 Jayhawk medium-range lift and recovery helicopters.

Expanded accommodation and working spaces

The conversion works on Storis entailed incorporation of additional berthing spaces to accommodate a larger crew complement and rebuilding of some of the lounges to enable these to serve as a damage control locker and additional offices.

The coast guard said that the vessel also received modifications to her communication and self-defence capabilities, though details on specific electronics and other equipment have not yet been made publicly available.

Storis has already completed a number of deployments for the coast guard, particularly in the Bering Sea. The coast guard said that the vessel’s patrols focused on advancing operational readiness, strengthening interoperability with other military assets, and testing new concepts to support prolonged operations in the Arctic.