Weather Routing

What it does

A weather routing clause deals with the use of a weather routing service, which advises on the vessel's optimal course in light of forecast weather and currents. The clause addresses whether the charterer may appoint such a service, whether its recommendations are advisory or binding, and how its data is used, particularly in assessing the ship's speed and consumption performance under a time charter.

The key tension is between the routing service's recommendations and the master's overriding responsibility for the navigation and safety of the ship. The clause typically preserves the master's authority to depart from a recommended route for safety, while allowing the routing data to be used as evidence of the weather actually encountered and of how the vessel performed, which connects it to the speed and consumption warranty.

Commercial effect

Weather routing matters most for performance measurement. The data a routing service provides on the weather actually met on a voyage is commonly used to judge whether the ship met its speed and consumption warranty, and whether under-performance occurred in good weather or was excused by heavy weather. The clause therefore feeds directly into performance claims and their evidence base.

There is also a navigational and cost dimension: an optimal route can save time and fuel, benefiting the charterer that pays for both, while the master must still navigate safely. How binding the routing is, and whose data prevails in a performance dispute, are the commercially important points, and they are read with the speed and consumption and heavy-weather provisions.

Owner's perspective

The owner wants the master's authority over navigation preserved, so that the routing service advises but does not override the master's judgement on the safe course for the ship. It is wary of a clause that would make the routing binding in a way that could compromise safety or expose the owner to blame for following or departing from a recommendation.

On performance, the owner wants the routing data used fairly, recognising the weather actually encountered, so that under-performance caused by heavy weather is properly excused rather than counted against it. It negotiates the clause so that the routing service informs the speed and consumption assessment without becoming a one-sided tool for building performance claims against the ship.

Charterer's perspective

The charterer, which pays for time and fuel, values weather routing for the efficiency it can bring and for the independent data it provides on the weather encountered. It wants the routing service it appoints to be respected and its data available to assess whether the vessel performed as warranted, treating that data as a fair and objective basis for any performance claim.

The charterer accepts the master's authority over safety but wants the routing to carry real weight in route selection and performance measurement, so that the efficiency it is paying for is actually delivered. It negotiates the clause alongside the speed and consumption warranty so that the routing data underpins a fair assessment of the ship's performance in the conditions actually met.

Negotiation points

• Whether a weather routing service is appointed and whether its advice is advisory or binding.
• The preservation of the master's authority over navigation and safety.
• How the routing data is used to assess speed and consumption performance.
• Whose data prevails in a performance dispute and the weight given to it.

Common variations

• An advisory weather routing clause with the master retaining route authority.
• A clause allowing the charterer to appoint a routing service for performance evidence.
• A clause designating the routing data as the basis for performance assessment.
• A provision integrating routing with the speed and consumption warranty.