As part of INSW’s long-term sustainability strategy, the partners set out to explore how much extra savings and emission reductions ship design, in conjunction with Norsepower Rotor Sails™ could provide to the concept.
The outcome is a resounding confirmation of the technology’s potential with total savings of up to 876 kW of propulsion power on one representative INSW MR tanker route from San Francisco to South Korea – equating to around 597.2 MT of fuel per annum, and the additional fuel savings attributable to the design contributing up to 13.5% of those savings in certain conditions.
“We focused on more than just energy savings and emissions reduction — our goal was a concept design that works in the real-world conditions of the MR trade.” explained Michael LaGrassa, Director of Performance and New Construction at INSW. “That meant ensuring reasonable build costs, equivalent cargo capacity, and a design fit for purpose. Our approach was to test a wide range of scenarios across the MR trade, rather than rely on selectively favorable assumptions.“
With Norsepower Rotor Sails at its core, Bluetech’s design modifications were demonstrated to extract signifanctly greater forward thrust. In one of the simulations, on a San Francisco–South Korea route, two 35m x 5m Norsepower Rotor Sails delivered an average propulsion power of 876 kW — equivalent to 597.2 MT of fuel annually. Bluetech’s Director of Energy Savings Solutions, Sam Robin, emphasised: “We set out to develop a ship that is entirely WASP-optimised while maintaining every essential operational feature and meeting trade-specific restrictions. The result is a vessel design that significantly enhances propulsion without compromising practicality.”
The SeaWasp project also investigated performance across less favourable wind conditions. On the South Korea–Singapore route, for example, savings of 185.9 MT of fuel were still achievable. This balanced approach was important to ensure the commercial projections of the project remained realistic.
Bluetech’s naval architects incorporated a range of innovations to maximise efficiency. “The BT50 design is itself approximately 12% more efficient than the typical tanker performance profiles in the sample fleet. Our design modifications enhance that efficiency even further,” said Robin.
Above the waterline, the design includes an aero superstructure and semi-enclosed mooring stations to reduce wind disturbance. Beneath the waterline, a new fin system dubbed ‘blueSURF’ was shown by CFD analysis to significantly increase power saving potential. Juha Hanhinen, Bluetech’s Head of Hydrodynamics, admitted: “We were surprised by how significant the fin effect was — it creates a powerful case for combining hydrodynamic improvements with wind propulsion.”
Norsepower also supported comparative studies of different Norsepower Rotor Sail™ configurations. “In the simulations related to this specific case, four 24m x 4m sails were marginally better, but overall, the two 35m x 5m sails offered the highest potential savings at lower cost,” explained Severi Sarsila, Sales Engineer at Norsepower.
