Heavy weather at sea: managing risks on passage in Marine Insurance P&I Club News 09/03/2026 Continuing our series on heavy weather risks, this article turns to the sea passage, when vessels may be more exposed to sustained or deteriorating conditions. We examine scenarios, decision points and operational pressures that can turn heavy weather into a potential casualty. In our last Insight we considered heavy weather risks in and leaving port. In this Insight we focus on the sea passage, when the ship and those onboard can soon find themselves without shelter and with limited assistance. Commence or delay the passage? Before the ship leaves shelter for a sea passage, it is prudent to assess whether departure should be delayed. It can allow heavy weather to pass through or more time to complete additional cargo and ship securing. The master may feel under commercial pressure to sail despite a deteriorating forecast or an under-prepared ship. Even without such pressure, there can be danger in leaving a decision to sail solely with the master. That was the indication from this investigation into a cargo shift that punctured tanks and flooded the hold, causing the vessel to list up to 45 degrees. Several crew members were injured and all were evacuated before the vessel was finally salved. Securing for departure It is normal to secure the vessel for potential heavy weather on passage, including anchors, openings and loose gear, especially on deck. The danger of leaving this work until after the vessel has left shelter is made clear further below. The forecastle needs particular attention as it will face the brunt of slamming forces and wave impact with potential for water ingress. Anchor securing also needs double checking. There are several known occurrences of an anchor becoming dislodged from its housing in heavy weather, with the vessel continuing underway not realizing that the paid-out anchor drags along the seabed damaging sub-sea infrastructure. In one case involving sub-sea cable damage, the crew assumed the increased engine load was a machinery issue in heavy weather. It was estimated the anchor had been deployed for approximately 31 hours before the crew discovered it. Passage planning and weather routeing Weather has always been a key consideration in passage planning and today high-capacity broadband makes it possible to provide connected ships with more real time information. Routeing costs, schedules, fuel efficiency, and emissions, even harnessing wind for propulsion, make routeing decisions today more operationally important than ever before. This has led to many more ships receiving weather routeing services from specialist companies ashore. Adjustments to passage plans are now made with increased frequency in the pursuit of optimization. Whoever stands to benefit most, increasingly complex commercial considerations are influencing decision making onboard. Even though SOLAS makes clear that masters shall not be constrained from taking decisions necessary to maintain the safety of the ship, support from their own company ashore remains important. This is particularly the case where a master may sense some commercial pressure to maintain a schedule or from a charterer who stands to benefit from route optimization. Relevant charterparty clauses recognize the discretion of a master to deviate from a charterer’s preferred route. The sophistication of weather routing services may nevertheless encourage greater reliance on assessm