How to Calculate Fuel Quantity in a Bunker Survey

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During a marine bunker survey, tank measurements and correction factors determine the calculated fuel quantity. The following example shows how to interpolate the volume and convert it to mass for one FO tank.

1. Data to collect

• The sounding measurement and tank capacity tables. Where required, correct the sounding for the vessel's trim and list before using the tables.
• The fuel temperature in the tank.
• The fuel density at 15°C, with its units clearly stated.
• The volume correction factor (VCF) and weight conversion factor (WCF) from the applicable tables. The original example uses ASTM Tables 54B and 56.

2. Example input data

3. Interpolate the observed volume

Interpolation uses two adjacent entries in the tank capacity table. Make sure that the correct tank table and correction conditions are used.

4. Convert volume to mass

In the original article's illustrative data, at 34°C and a density of 0.9903 t/m³, the VCF is taken as 0.9870 and the WCF as 0.9892 t/m³. These factors apply only to this example and must not be assumed for every fuel consignment.

The original article describes estimating WCF as density at 15°C minus 0.0011, when density is expressed in t/m³. For an official report, use the method and factors appropriate to the agreed mass calculation basis; a general shortcut formula must not replace checking the applicable tables.

5. Checks before preparing the report

• Check that the units are consistent: m³, kL, metric tonnes and density.
• For data expressed in barrels, use the corresponding tables and conversion factors; the original article refers to ASTM Tables 6B, 11 and 13.
• Calculate each tank separately, record the data sources and round only at the final reporting stage.
• Cross-check the attached calculation sheet; the correct temperature for this example is 34°C.

ITVC performs bunker surveys in Hai Phong, Ho Chi Minh City, Da Nang, Nghi Son, Vung Tau, Phu My and other requested locations.