Two very large crude carriers (VLCCs) on order for Idemitsu Tanker Co Ltd in Japan have been described by the marine equipment supplier as the first VLCC newbuildings contracted to be equipped with rotor sails, with delivery scheduled from the end of 2028 according to the companies.
The vessels will be built by Japan Marine United Corp and Nihon Shipyard Co Ltd and each will be fitted with two large explosion-proof Norsepower rotor sail units, integrated into a wider package of energy-saving technologies and methanol-ready machinery.
According to Idemitsu Tanker, its Nissho Maru VI project will adopt a methanol dual-fuel main engine, a large shaft generator and two rotor sails, with an indicated unit cost of about US$135M for each VLCC.
Norsepower noted its rotor sails are already in operation on tankers ranging from smaller chemical ships through MR and LR tankers to very large gas carriers, and the Idemitsu pair would extend this track record into the VLCC segment for the first time.
The rotor sails are derived from the Flettner concept, using powered spinning cylinders to generate additional thrust through the Magnus effect, and Norsepower’s material highlights a claimed 5–25% reduction in fuel consumption depending on route and operating profile, though those figures will need to be validated once the VLCCs enter service.
Wind-assisted propulsion VLCCs are not entirely new: in November 2018, Dalian Shipbuilding Industry Co reported delivery of the VLCC New Vitality with a sail device installed, describing it as the first 308,000-dwt VLCC to be fitted with a wind sail.
2022-built, 306,500-dwt VLCC New Aden was reported to deploy four 40-m rigid wing sails, and it was estimated these will cut average fuel consumption by nearly 10% and CO2 emissions by 2,900 tonnes on the Middle East to Far East route.
While New Vitality and New Aden demonstrate rigid wing sails have already been taken to sea at VLCC scale, rotor sails on VLCCs have, until now, remained at the design and approval stage.
In June 2019, Norsepower rotor sail technology was part of a VLCC study to lower fuel consumption and emissions.
In March 2021, a DNV approval in principle for a DSME rotor-sail system described it as “designed for use on large oil tankers and LNG carriers”, and reported DNV’s statement confirmed no major obstacles to realising the concept after a review of plans for classification purposes.
The Idemitsu project therefore sits at the intersection of several strands of development as Chinese-built VLCCs have already operated with rigid wing sails for several years, with New Vitality and New Aden providing early operational data for wing-based systems.
