Bunker Survey – Procedure & Calculation

BUNKER SURVEY - PROCEDURE AND CALCULATION - MASCOTMARITIME

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What is an onboard bunker survey or bunker quantity survey (BQS)?

It is a process to ascertain the exact quantity of bunker on board the ship at any given point in time.

The bunker survey is conducted before & after the ship receives bunker after bunker operation (as a loss control tool to ascertain any difference in the supply of bunker) or during delivery or re-delivery of the vessel from owners to charterers or from charterers to owners.

The survey may also be carried out during on /off hire surveys, as per owners/charterers’ requirements.

What are the tools needed for bunker surveys?

1) Sounding Tape & oil water paste.

2) Thermometer.

3) Density Meter for Oil (range 0.750 -1.000).

4) Petroleum ASTM Table 54B (for Product Oil) and Table 56.

5) Ship’s tank sounding table & tank capacity table.

6) Notebook, pen/pencil, Gloves, and Goggles.

7) Flashlight.

8) Sampling bottles or cans (for taking samples).

9) Seals (sealing bunker sample bottles).

Bunker survey procedures & calculation.

1. If any bunker surveyor is appointed then the surveyor must have a letter of appointment from the principal to conduct a bunker survey on board. Normally the Master is well informed of the survey by owners/charterers.

2. Check the Ship’s Draft fore and aft to get the ship’s trim, for trim correction.

3. Check the ship’s list for List Correction.

4. With the Chief Engineer or his appointee, check the onboard certified tank sounding table and verify the number of bunker tanks, their location, reference height & depth.

5. Check & confirm the measuring method to be used, either sounding or ullage depending on the types of oil ( light or heavy )

6. Check the Last Bunker supply report to ascertain the oil density in the tanks, if any.

7. Check and record the quantity of bunker onboard as per Engine Logbook.

8. Check the accuracy of the sounding tape which will be used for measurement.

9. Check & record sounding/ullage each oil Tank & temperature and oil density in tanks.  For some tanks like service and settling tanks, the tank gauge may be used to determine quantities, also the temperatures can be checked from the attached thermometers and the density from the engine logbooks.

10. If old oil is mixed with new oil (usually to be avoided), then commingle density needs to be calculated as below:

[(Qty of old oil x oil density / Total oil in Tank) + (Qty of new oil x oil density / Total oil in Tank)].

11. Taking all parameters (trim, list, sounding/ullage) into account the “corrected sounding” is derived from the ship’s tank sounding table.

With the observed temperature of oil in tanks & given oil density of @15 deg C, necessary correction factors determined from ASTM Table 54B to ascertain the Volume Correction Factor (VCF – to convert from Cubic meter at Observed temp to Cubic meter at 15 deg C) and from ASTM Table 56 for Weight Correction Factor (WCF – to convert from Cubic meter at 15 deg C to weight in Metric Ton).

The quantity of oil (in Metric Ton) = Oil Vol x VCF x WCF

The same procedure is repeated to determine the quantity of oil in each tank and finally, the total bunker quantity is ascertained.

A Bunker Survey report is issued by a surveyor with the Chief engineer’s signature and countersigned by the Master.

As per instruction from the Principal, the surveyor to take oil samples and seal the bottles with proper seal with numbers. The required number of sealed sample bottles may be left on board for future use & acknowledgment obtained from the Chief engineer. 

NB: To calculate volume in barrel use ASTM Table 6B for VCF, ASTM Table 11 for WCF in Long Ton, and ASTM Table 13 for WCF in Metric Ton.

Frequently Asked Questions (FAQs)

What does bunkers mean in shipping?

Bunkers denote marine fuel oil, marine diesel oil, or marine gas oil supplied for vessel use, serving as a general term for ship fuel. 

What is bunker survey ? 

The bunker survey is conducted to accurately measure the quantity of Bunker onboard at a given time. This survey yields a report detailing the amounts of bunker, predominantly Fuel Oil (FO) and Diesel Oil (DO), Marine Gas Oil(MGO) occasionally incorporating Lubricating Oil (LO). The report provides crucial information regarding the inventory of these oils, ensuring effective management and planning for maritime operations.

A bunker survey is also performed to ascertain the quantity of bunker while on-hiring and off hiring vessels.

Who is a bunker surveyor?

Typically, a bunker surveyor is a qualified person who is primarily hired to autonomously verify and ascertain the quantity delivered by the bunker barge and received by the vessel. Both quantities must typically fall within an acceptable tolerance range (usually 0.5% of the received quantity). If not, the surveyor is responsible for investigating the cause of the deviation.

A bunker surveyor is often employed to ascertain the quantity of bunkers during on-hire and off hire of a vessel.

What is VCF and WCF?

The volume correction factor (VCF) is used to convert the volume at the observed temperature to the “standard volume” which is volume at 15 Deg C or Volume at 60 F . 

The weight correction factor (WCF) is used to convert the “standard volume” to weight.

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