A practical overview of how a bunker delivery actually happens — from nomination to final quantity agreement — and where the operational and commercial risks sit.
The process starts with a stem nomination — typically 3-7 days before delivery for standard grades at established ports, longer for specialty fuels. The nomination specifies vessel, port, grade(s), quantity, ETA, and any specific delivery requirements (max viscosity, max pour point, specific origin, ISO 8217 edition). Commercial terms follow: price basis (fixed or indexed), payment terms, demurrage provisions, quality-claim procedures.
Before the barge arrives, the vessel prepares receiving tanks: cleans and measures existing contents, plans segregation, and opens appropriate valves. The bunker plan — documenting which tanks will receive, in what order, with what expected quantity — is agreed between Chief Engineer and bunker supplier's barge master. MARPOL requires a documented bunker operation procedure.
The barge moors alongside. Hoses are connected; the vessel verifies that the barge's documentation is in order (previous stem records, tank soundings, flow meter calibration certificates if MFM supply, ISGOTT compliance for tanker barges). Pre-transfer safety checks — ship-barge communications, shut-down procedures, emergency stop, drip trays, boom deployment — are completed and signed off on both sides.
Both parties measure starting tank quantities — on the vessel and on the barge — using sounding tape or remote gauging plus temperature measurement. Volumes are converted to mass using observed density and ISO 91 table corrections. This establishes the baseline. If a surveyor is present, the surveyor coordinates and witnesses.
Pumping begins at agreed rate. During transfer, both sides monitor flow, pressure, and tank levels. If Mass Flow Meter (MFM) is used — as mandated at Singapore and increasingly used elsewhere — the delivered quantity is recorded directly by the meter system. Without MFM, quantity is determined by tank gauging before and after.
When transfer completes, both parties again measure tank levels on ship and barge. Drip samples are taken during transfer per MARPOL; a composite retained sample is sealed for each grade delivered and signed by both parties. The vessel retains sealed samples for at least 12 months; the barge retains the corresponding samples.
The BDN is issued, documenting product supplied, quantity (in mass), density, flash point, sulphur content, delivery date/time, and vessel/barge details. Quantity can be in dispute; the BDN is signed 'under protest' if necessary. MARPOL requires BDN retention for three years. Commercial payment follows contractual terms.
Many operators send retained samples to third-party labs for comprehensive ISO 8217 analysis. Results arrive days later. If off-spec, formal written notice to supplier, potential third-party expert survey, and commercial claim process begins. The retained samples are the evidentiary basis for any dispute.
Seven Ocean procures marine fuel at every major global hub. Tell us the vessel, the port, the grade, and we'll come back with a stem.
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