Heavy fuel oil and marine gas oil are used in many marine applications. Wikipedia relates the term bunkering:
…to storage of petroleum products in tanks (among other, disparate meanings.) The precise meaning can be further specialized depending on context. Perhaps the most common, more specialized usage refers to the practice and business of refueling ships. Bunkering operations are located at seaports, and they include the storage of “bunker” (ship) fuels and the provision of the fuel to vessels. 
Alternatively the term “bunkering” may apply to the shipboard logistics of loading fuel and distributing it among available “bunkers” (on-board fuel tanks.)
Bunkering measurements can occur at transfer points between storage terminals and barges, between barges and other ships, and within a ship’s fuel system to measure overall efficiency:
A YouTube video case study, CYE Petrol: Proven Success with Micro Motion Bunkering Solutions shares the story of how CYE Petrol sought to double bunker deliveries within a year–by installing Micro Motion Coriolis flowmeters as part of a Certified Marine Bunker Measurement solution–and nearly did so in the first 6 months alone.
Using the Certified Marine Bunker Measurement Solution helped to improve CYE Petrol’s overall operational efficiency and raise their customers’ confidence in the quality of bunker deliveries. The mass-based Coriolis flow measurements are Measuring Instrument Directive (MID) approved to meet international standards for custody transfer and reduce measurement uncertainty that can lead to disputes or delayed vessel movements.
The Certified Marine Bunker Measurement Solution includes a Micro Motion ELITE Coriolis meter, Series 3000 transmitter with Marine Bunker Transfer Package, and bunker delivery ticket printer to generate a receipt that includes the time, date and the total quantity transferred. This receipt can be used as a legal weights and measures document. The globally-certified custody transfer system enables bunker suppliers to very accurately monitor fuel deliveries and improve operational efficiencies.
You can connect and interact with other flow measurement experts in the Flow group in the Emerson Exchange 365 community.