The historical average ratio of a tanker's total calculated cargo volume to the shore Bill of Lading quantity, used to reconcile ship and shore figures.
Quick facts
Type
Ratio (ship volume ÷ shore B/L)
Use
Ship/shore reconciliation
In practice
Loading terminals and receivers compare the ship's figure, adjusted by the VEF, against their own measurement. A result outside the agreed tolerance prompts a re-gauge and, if unresolved, a letter of protest. A ship with too few qualifying voyages, or a recent tank modification, may not have a valid VEF.
Regulatory detail & full definition
The Vessel Experience Factor (VEF) is a running average, compiled over a number of qualifying voyages, of the ratio between the ship's total calculated (or total calculated after loading) volume and the corresponding shore-measured Bill of Lading quantity. Because ship and shore use different gauging systems, tables, and reference points, their figures almost never agree exactly; the VEF captures a given ship's consistent bias so that its load or discharge figure can be adjusted to an expected, reconciled quantity. It is calculated separately for loading (VEFL) and, where used, discharge, following industry guidance such as the API MPMS and OCIMF procedures, with outlier voyages excluded. In practice the VEF is a screening tool: if an actual transfer falls outside the tolerance around the VEF-adjusted expectation, it signals a possible measurement error, cargo shortage, or retention that should be investigated and, if warranted, protested before documents are signed.