A mineral export project may appear attractive when production costs, selling prices, and indicative ocean freight are entered into a financial model. Yet shipping assumptions are often not tested against port conditions or the vessel market.
The problem usually emerges when the first cargo approaches shipment. The parcel may not be ready within the expected laycan, the nominated vessel may exceed berth limits, the terminal may not achieve its advertised loading rate, or suitable tonnage may cost more than assumed. By then, production, inland transport, and delivery commitments may already be fixed.
Mining companies and commodity traders should therefore stress-test seven assumptions before relying on their shipping model.
1. Production capacity is not cargo readiness
A mine’s production schedule does not establish when a complete shipment will be available at the port. Processing, quality verification, weighing, storage, and inland transportation still have to be completed, while railway or trucking capacity may become the limiting factor.
Shipping readiness should be calculated backwards from the proposed laycan. A vessel should be fixed against a realistic cargo-delivery programme, not a theoretical production date.
2. Parcel size must work across the complete route
Larger shipments can reduce freight per tonne, but the biggest parcel is not automatically the most economical. Quantity must be compatible with production, inland transport, storage, loading and discharge ports, and available vessels.
A port may accept a vessel’s deadweight while restricting its draft, length, beam, air draft or manoeuvring. If the receiving berth is more restrictive, the exporter may face a smaller parcel, lightering, an alternative port, or transshipment. The correct parcel is the quantity that can move efficiently through every stage.
3. Published port limits require operational confirmation
Port data in brochures, databases, or feasibility studies should not be treated as permanent. Draft may change because of silting, seasonal water levels, or dredging. Turning space, shiploader outreach, berth length, and mooring arrangements may impose further limits.
Equipment availability, trimming capability, and restrictions on night or weekend working must also be checked. Current limits should be confirmed with terminals, agents, and shipbrokers before firm freight offers are requested.
4. Nominal loading capacity is not effective productivity
A shiploader’s rated tonnes per hour rarely represents performance across an entire port call. Cargo delivery, stockpile configuration, hatch changes, trimming, sampling, surveys, equipment stoppages, and weather all reduce effective productivity. Vessel design also matters: several smaller holds may require more movements than fewer large openings.
Laytime should therefore reflect sustainable daily performance. An unrealistic contractual loading rate can create demurrage even when local operations are proceeding normally.
5. Vessel availability must be tested against the market
Availability depends on vessel size, position, trading pattern, cargo acceptance, age restrictions, and voyage attractiveness. Owners also consider ballast distance, duration, bunker consumption, port risk, and the vessel’s next employment.
There may be many ships of the required deadweight but few that are technically suitable, geographically competitive, and available during the laycan. An assessment of dry bulk cargo chartering should identify the vessel segment likely to serve the project and where those ships normally trade, rather than applying a general index to a specialised route.
6. The lowest freight may produce a higher final cost
Freight per tonne is only one component of transportation cost. Vessels may differ in intake, draft, demurrage, crane arrangements, and port-call duration. A cheaper ship that cannot load the intended quantity may cost more per delivered tonne.
Comparisons should include handling terms, port disbursements, shifting, trimming, surveys, possible lightering, weather exposure, and delay. The decisive figure is the realistic total cost of delivering the contracted quantity.
7. The charter party must reflect the logistics chain
Cargo readiness, notice of readiness, berth availability, weather interruptions, shifting, draft surveys, trimming, and terminal stoppages should be addressed before fixing. If cargo arrives by rail or truck during loading, responsibility for inland supply interruptions must also be clear.
General wording can become disputed once demurrage accumulates. The charter party should reflect the actual project rather than copy terms from a voyage involving different ports and risks.
Building resilience into the plan
The project should test alternatives: a smaller vessel, divided shipments, a wider laycan, or another port. It should also model lower terminal productivity, higher freight, and delayed cargo accumulation.
For mineral exporters, the right vessel is not necessarily the largest or the cheapest. It is the vessel capable of completing the voyage within the practical limitations of the cargo, ports, and complete logistics chain.
