Heerema Marine Contractors and Amphitrite shortened the North Atlantic transit of the semi-submersible crane vessel Sleipnir by 2.5 days in a vessel-specific voyage optimization pilot.

The optimized crossing reduced the sailing distance by 240 nautical miles and lowered CO₂ emissions by up to 18%. Sleipnir also maintained a higher average speed without an increase in fuel consumption.

The pilot used five years of operational data supplied by Heerema to create a model of the vessel’s speed and power demand under changing weather, wave and ocean current conditions. Amphitrite combined the vessel performance model with high-resolution ocean, wave and weather data to support route planning.

Sleipnir was mobilizing from Rotterdam to New York to install an offshore wind substation. During the North Atlantic winter crossing, the routing model responded to rapidly changing winds, waves and currents.

After departure, the system selected a sailing window that allowed the vessel to use favorable tidal flow through the English Channel. It later recommended a more northerly route around a developing storm, enabling Sleipnir to benefit from tailwinds while remaining close to the great-circle route.

A different strategy was used for the return crossing. Instead of directing the vessel along the shortest route, the model guided Sleipnir towards the Gulf Stream. The longer course allowed supporting currents to raise the vessel’s speed over ground to 14.6 knots, reducing the total transit time.

The pilot also provided Heerema with further information on Sleipnir’s performance during transit. Alejandro Velez Isaza, Decarbonization Engineer at Heerema Marine Contractors, said the findings created additional opportunities to optimize fuel consumption during this phase of operations.

The collaboration forms part of Heerema’s use of Amphitrite’s Ocean Bulletin across its fleet. The service supports crews and operational teams with ocean data for voyage planning and offshore project preparation.