7.6.3 Changes in Cargo Stowage
When a vessel has loaded a part cargo, unless the vessel has compiled / produced a compartmental VEF for the specific tank combinations and tank load conditions, which is very rare, the VEF adjusted ships figure may be unreliable.
• External: cargo that escapes from vessel tanks to the sea. • Internal: cargo that escapes to other cargo tanks or into voids, cofferdams, slop tanks, ballast tanks, or other non-designated areas but is not discovered. • Unreported cargo diversion, or cargo burned as fuel. • Transfer or decanting of free water from slop or dirty ballast tanks during voyage. If a vessel shows more cargo on arrival at the discharge port than was reported on departure from the load port, the cargo volumes and measurements should be carefully reviewed and analyzed. Caution should be exercised when recording transit variations since such variances may or may not have any bearing on the overall gain or loss. For example: • A large transit loss, with no corresponding difference between VEF adjusted vessel volume versus outturn at discharge, might indicate a physical loss during the voyage. • A large transit gain, with a large vessel / shore difference at the load port and minimal differences noted at discharge, might indicate vessel measurement errors caused by gauging in rolling seas, the use of different calibration tables at each port, or a change in the reference gauge point.
Stowage refers to the arrangement of cargo in the vessel. Changes in stowage should be investigated some examples are: • A request from Charterers for blending of cargo en-route or heating and / or circulation of cargoes between two or more tanks.
7.6.2 Transit Differences
A comparison of the vessel’s departure TCV and its arrival TCV will give an indication of transit cargo variation. The measurements which make up the TCV (GSV and FW) should be reviewed individually.
• The need to alter the vessel’s trim for stability / performance or to facilitate load/discharge.
7.6.4 Cargo Diversion
Any unauthorized diversion of cargo must be fully investigated and reported.
A transit gain may be due to:
Bunker survey reports and receipts should be obtained where appropriate.
• Material pumped from engine room bilges into slop tanks.
• Heating coils leaking into cargo tanks.
7.6.5 OBQ and ROB
• Displacement into cargo tanks of other materials, which were received/discharged between the time when cargo load and discharge measurements are made, e.g. bunkers, slops, and other parcels.
A difference in On-Board Quantity (OBQ) and Remaining On-Board (ROB) quantities may be expected as a result of unmeasured ROB or Clingage which may later settle to the bottom of the tanks and then become measurable as OBQ for the next voyage. ROB Clingage which does not settle can result in shore to ship cargo gains at next Loadport.
• Introduction of water to cargo tanks.
• Measurement inaccuracy due to vessel motion and/or equipment limitations.
• A physical transit loss may be due to:
• Vapour losses.
• Leaks.
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