Heavy Weather

What it does

Heavy weather provisions address how adverse weather affects the vessel's performance and the parties' obligations. In a time charter they qualify the speed and consumption warranty, so that the ship is not judged to have under-performed when reduced speed or higher fuel use is caused by weather beyond a stated severity, commonly defined by reference to wind force or sea state.

Heavy weather also bears on the master's navigational decisions, since the master may slow down or alter course for safety, and on voyage-charter laytime where weather can interrupt cargo operations. The provisions therefore define the weather conditions that excuse performance shortfalls and that justify the master's actions, linking to the weather-routing, speed and consumption, and laytime provisions.

Commercial effect

The treatment of heavy weather decides who bears the consequences of bad weather slowing the ship or interrupting operations. In a time charter, defining the weather that excuses under-performance protects the owner from performance claims for matters outside its control, while a narrow definition exposes it to claims; the line drawn is therefore commercially significant over a long charter.

In voyage charters, weather can affect laytime counting where the cargo operation is weather-dependent, connecting heavy weather to the weather working days regime. Across both, the provisions allocate a natural and unavoidable risk, and the precision of the weather definitions, the wind force or sea state thresholds, determines how predictably that risk falls.

Owner's perspective

The owner wants heavy weather clearly defined as excusing reduced speed and increased consumption, so that the ship is judged on its performance only in the conditions for which the warranty was given. It relies on this to avoid being held to warranted figures when weather beyond the agreed threshold legitimately slows the vessel or increases her fuel use.

The owner also wants the master's authority to navigate safely in heavy weather preserved without penalty, so that prudent slowing or course changes are not treated as breaches. It negotiates the weather thresholds and their interaction with the speed and consumption warranty so that genuine weather effects are excused and the warranty remains a fair description of the ship's capability.

Charterer's perspective

The charterer accepts that genuine heavy weather affects performance but wants the threshold set so that only real adverse weather excuses under-performance, not ordinary conditions the ship should handle. It wants the definitions tight enough that the owner cannot use a generous weather allowance to escape a warranty the charterer is paying for.

In voyage trades the charterer is concerned with how weather interruptions affect laytime, wanting the treatment consistent with the weather working days regime so that weather delay falls where the laytime bargain intended. It negotiates the heavy weather definitions alongside the performance and laytime provisions so that the weather risk is allocated as the deal contemplated.

Negotiation points

• The definition of heavy weather by wind force, sea state, or similar threshold.
• How heavy weather excuses speed and consumption shortfalls under a time charter.
• The interaction with laytime counting where weather interrupts cargo operations.
• The preservation of the master's authority to navigate safely in heavy weather.

Common variations

• A weather threshold (for example a stated wind force) above which performance is excused.
• A clause linking heavy weather to good-weather sampling for performance.
• A voyage-charter provision aligning weather interruption with weather working days.
• A clause confirming the master may reduce speed or alter course for safety.