Speed & Performance - Discrepancies Between Ships' Data And Independent Weather Bureaus

In the current climate, we are seeing increasing attempts by charterers to withhold hire on the basis that the vessel did not meet its contractual performance warranty.

The law on the issue is well settled; since The "DIDYMI" [1988] it has been accepted that, if a vessel fails to meet its performance warranty in good weather, then it is also deemed to have underperformed during periods of bad weather. Therefore, charterers need only show the vessel underperformed (or over-consumed) during periods of good weather to claim underperformance for the duration of the voyage/charter.

How one measures the number of good weather days becomes complicated when there is a discrepancy between the weather and sea state conditions recorded in the vessel's logbooks, and information from independent weather bureaus, as standard charterparty wordings are silent on which should take precedence.