Speed and consumption claim calculator.

The good-weather distance is divided by the warranted speed, less any allowance, to give the time the vessel should have taken. If the vessel actually took longer, the difference is the time lost, which is usually valued at the daily hire rate.

The warranted daily consumption, plus any allowance, is multiplied by the number of days in the measurement period to give the fuel allowed. Fuel consumed above that figure is over-consumption, valued at the bunker price. Some tribunals measure the allowed fuel over the actual good-weather time and others over the time the vessel should have taken, so the calculator lets you choose.

In English arbitration practice, “about” has commonly been read as allowing around 0.5 knot on speed and 5% on consumption, but this is not a fixed rule. Some charters exclude the allowance, use different figures, or add “without guarantee”. Enter the allowance that matches your wording.

Arbitrators have often accepted that a vessel’s performance in good weather is a fair guide to its performance throughout the passage, so results are commonly extrapolated pro rata to steaming time. Owners may argue against it where conditions or instructions changed. Tick the option only if extrapolation is appropriate for your case.

Common arguments include that the good-weather days were wrongly identified, that currents or swell distorted the data, that charterers ordered slow or economical speed, that hull fouling was caused by charterers’ trading orders, or that the bunkers supplied by charterers were off-specification.

Under English law, a reasonable, good-faith deduction for a well-founded performance claim may be possible by way of equitable set-off, but an unjustified deduction risks a claim for unpaid hire or withdrawal of the vessel. Calculate and document the claim carefully before deducting.