Heerema Marine Contractors has shortened the North Atlantic transit of its semi-submersible crane vessel Sleipnir by 2.5 days using a data-driven voyage optimization pilot with French ocean intelligence company Amphitrite. The optimized crossing reduced the sailing distance by 240 nautical miles and cut CO₂ emissions by up to 18%, while maintaining higher average speeds without increasing fuel consumption.

The pilot combined Heerema’s offshore expertise with Amphitrite’s vessel-specific voyage optimization platform, using five years of operational data supplied by Heerema to develop a model that predicts Sleipnir’s speed and power consumption under changing weather, wave and ocean current conditions. Unlike generic weather routing, Amphitrite’s approach combines vessel-specific performance modelling with high-resolution ocean current, wave and weather intelligence.

Sleipnir, world’s largest semi-submersible crane vessels, was mobilizing from Rotterdam to New York to install an offshore wind substation. North Atlantic winter conditions put the vessel to the test, with rapidly changing winds, waves and ocean currents providing a demanding proving ground for the routing model

Shortly after departure, the system identified the optimal sailing window to benefit from tidal currents in the English Channel. As the crossing progressed, it recommended a more northerly route around a developing storm, allowing Sleipnir to make use of favourable tailwinds while remaining close to the great-circle route.

The return crossing demonstrated another advantage of dynamic voyage optimization. Rather than following the shortest route, the model directed Sleipnir towards the Gulf Stream. Although the vessel covered a greater distance, favourable currents increased its speed over ground to 14.6 knots, reducing the overall transit time despite the longer route.

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

Beyond the operational gains, the pilot also gave Heerema new insights into how Sleipnir performs during transit. “Improving fleet efficiency is fundamental to our decarbonization strategy,” said Alejandro Velez Isaza, Decarbonization Engineer at Heerema Marine Contractors. “Working with Amphitrite not only demonstrated the value of vessel-specific voyage optimization, but also gave us a better understanding of how Sleipnir behaves during transit. Those insights create further opportunities to optimize fuel consumption during one of the most energy-intensive phases of our operations.”

For Amphitrite, the project demonstrates how vessel-specific modelling helps offshore operators and shipping companies unlock meaningful efficiency gains. Thomas Joyce, Head of Business Development at Amphitrite, said: “This collaboration with Heerema shows the value of combining vessel-specific models with high-resolution ocean intelligence. Offshore vessels such as Sleipnir operate in highly dynamic environments, where currents, waves and weather can materially affect performance. By bringing these factors into routing decisions, we can help crews and operators make better-informed choices that reduce transit time, fuel consumption and emissions.”

The pilot demonstrates that vessel-specific voyage optimization can deliver measurable operational and environmental benefits for complex offshore assets. For Heerema and Amphitrite, it also shows how data-driven routing can translate directly into shorter transits, lower emissions and more efficient offshore vessel mobilizations.