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TL;DR: Weather routing is the practice of planning and adjusting a ship's route and speed around forecast wind, waves and currents to protect the vessel, the cargo and the schedule while reducing fuel consumption. It began as a shore-based advisory service; today it is increasingly one input inside broader voyage optimisation, where weather is combined with vessel-specific fuel models, Charter Party terms and emissions cost. Standalone routing services suit fleets that want advice; voyage optimisation platforms suit fleets that want the whole voyage decision, continuously re-optimised.
What is weather routing?
Weather routing is the process of selecting, and updating, the optimum route and speed for a ship based on forecast weather and sea conditions: wind, wave height, swell, currents and visibility. The aim is to avoid dangerous or fuel-punishing conditions while meeting the vessel's schedule, sometimes called optimum ship routing.
The practice matters because weather is the single largest external influence on a voyage. Adverse seas add hull resistance and involuntary speed loss, burn more fuel for the same distance, stress crew and cargo, and put the arrival window at risk. A well-routed vessel sails further around a system yet arrives earlier, on less fuel, than one that ploughs through it.
How weather routing works
Modern weather routing combines three ingredients:
- Forecast data: gridded marine forecasts (wind, waves, swell, currents) updated several times a day across the route.
- A vessel model: how this ship responds to those conditions, its speed loss, motions and consumption in a seaway. The more vessel-specific the model, the more trustworthy the routing.
- Constraints: arrival windows, Charter Party speed and consumption clauses, safety limits such as maximum wave height, and no-go areas.
The routing engine simulates thousands of route and speed combinations against the forecast and recommends the best available plan, then re-runs the exercise as new forecasts arrive. Traditionally this analysis was delivered as shore-based weather routing: a routing agency's meteorologists advising the master by message. Increasingly it runs as software onboard and ashore simultaneously, so the ship and the operator see the same picture and update it in near real time.
What weather routing saves
Routing around adverse weather reduces added resistance, involuntary speed loss and heavy-weather damage risk, and it is one of the levers behind the 3 to 10% per-voyage fuel and emissions savings that data-driven routing and speed decisions deliver. The full mechanism, weather plus speed plus vessel-specific fuel models, is covered in how voyage optimisation reduces fuel, emissions and risk. The safety benefit is harder to put a single number on but shows up as fewer heavy-weather incidents, less cargo damage and fewer missed laycans.
Weather routing services and companies compared
The market splits into three kinds of provider, and the honest answer is that they solve different problems:
Weather routing vs voyage optimisation: which do you need?
Weather routing answers one question: what is the safest, most efficient track through the forecast? Voyage optimisation answers the bigger one: what is the most profitable compliant plan for this voyage, of which weather is one input alongside speed, fuel, Charter Party terms and carbon cost. Weather routing tells you where to sail; voyage optimisation decides how the whole voyage makes money.
A practical decision rule: if your pain is the occasional heavy-weather passage, a routing service is enough. If your pain is fuel spend, CP claims, CII exposure or ship-shore misalignment, weather routing alone will not fix it: that is voyage optimisation territory. Operators like TMA Bulk run the second model, treating routing as one part of commercial optimisation, including across sequential multi-leg operations.
The bottom line
Weather routing has moved from a shore-side advisory message to a live input inside data-driven voyage decisions. The category successor is voyage optimisation: routing, speed and fuel decisions in one continuously updated, commercially aware plan. Book a demo to see both layers working together on your trades.
