Marine Forecasts Can Miss Wave Conditions Linked To Dangerous Vessel Rolling & Cargo Losses

New analysis from Sofar Ocean finds that widely used marine forecasts can miss wave conditions associated with dangerous vessel rolling and cargo losses.

Most forecasts tell ships how high waves will be. But height alone doesn’t identify the impact on a ship. Wave period and direction, together with the vessel’s heading, speed, and loading, can create dangerous rolling even when waves don’t appear extreme.

Most marine forecasts have limited direct, in-water observations of the full wave field. As a result, wave period and direction can be harder to resolve accurately, even though both can be critical to how a vessel responds at sea.

Sofar Ocean’s whitepaper examines the December 2025 Baltic Klipper incident, when the refrigerated cargo vessel shed part of its cargo off the Isle of Wight, England. Wave heights on the day were not extreme, but long-period swell exceeded 15 seconds. Standard forecast products did not identify that risk. Sofar’s forecast used direct measurements of the swell earlier in its path and identified the risk more than two days ahead.

This finding matters as more vessels choose routes through areas such as the Cape of Good Hope. IUMI reported in September 2025 that heavy-weather claims had “spiked”, linked to Red Sea rerouting. Cefor has also reported a rise in heavy-weather hull claims as vessels move through more weather-exposed areas with reduced visibility.

“Wave height is only part of what we look at when assessing risk,” said Jessica Topal, Senior Routing Specialist at Sofar Ocean. “The timing and direction of the waves, together with the vessel’s heading and speed, determine how the ship will actually respond. Two sea states with the same wave height can create very different conditions onboard.”

The white paper also revisits major container-loss incidents involving Svendborg Maersk and CMA CGM G. Washington. Across the cases, the weather systems themselves were generally known in advance. The gap was in describing the wave characteristics that determine vessel motion.

Sofar Ocean’s analysis shows why measuring the full wave field matters: direct observations can improve understanding of wave period and direction, helping identify major risks that wave height alone can miss.

Read the full white paper: The Maritime Weather Forecast Gap Is an Operational Risk.

Press Release