Good Weather Methodology to Comply English Case Law
Charter party agreements typically warrant a vessel’s speed and consumption during good weather conditions. This means that a warranty only takes effect once good weather conditions have been encountered. English Case Law precedent indicates that a vessel’s performance may be assessed in good weather conditions then applied (extrapolated) to the entire voyage distance in order to assess the vessel’s total voyage performance. English Courts have described this “Good Weather Method” in detail via the following cases:
The Didymi  2 Lloyd’s Rep. 166
The Gas Enterprise  2 Lloyd’s Rep. 352
The principles from these cases must be applied by lower courts and arbitration tribunals. Indeed, there are numerous arbitration awards* that have applied the good weather method as described by The Didymi and The Gas Enterprise (*hyplerlink these words to LA awards that apply the Didymi/Gas Enterprise concepts). The good weather method as described through case law may be applied as follows:
(1) Complying with the charter party good weather definition, good weather days are assessed to measure the good weather speed / consumption.
(2) The time / consumption for the whole voyage at the good weather speed / consumption is compared to the time / consumption for the whole voyage at the charter party speed / consumption.
(3) The difference between (1) and (2) above represents a time loss (or savings) / over-consumption (or under-consumption).
WNI Official Performance Auditing