Wheat is the largest grain seaborne cargo, with global seaborne trade of approximately 200 to 220 million tonnes per year. The cargo is principally moved from major exporting regions (Russia, the United States, Canada, Australia, Argentina, the European Union, and Ukraine) to import markets including the Middle East, North Africa, Sub-Saharan Africa, and Southeast Asia. Wheat is regulated under both the International Code for the Safe Carriage of Grain in Bulk (the International Grain Code) and the IMSBC Code, with the Grain Code providing detailed stability and trimming requirements specific to grain cargoes.
Regulatory framework
Bulk grain shipments are governed by:
- International Grain Code (1991, IMO Resolution MSC.23(59)): the principal regulation for grain stability, trimming, and shifting prevention.
- IMSBC Code Group C entry for grain: cross-references the Grain Code and provides the standard cargo declaration framework.
- SOLAS Chapter VI: incorporates the Grain Code and the IMSBC Code into international convention status.
The Grain Code is invoked by reference rather than reproduced in the IMSBC schedules; it imposes specific stability calculations, hold trimming requirements, and shifting board provisions designed to prevent the catastrophic stability loss that historically caused multiple grain ship casualties.
Cargo properties
Wheat is supplied as whole kernels with bulk density of approximately 0.75 to 0.80 tonnes per cubic metre, with stowage factor of approximately 1.25 to 1.35 cubic metres per tonne. Moisture content at loading is typically 10 to 14 per cent. The cargo is non-toxic, non-flammable, and not classified as a hazardous chemical cargo, but presents specific carriage hazards related to free flow, shifting, and chemical changes during voyage.
Grain shifting hazard
Bulk grain has a low angle of repose (approximately 20 to 25 degrees) and flows freely under ship motion. Without trimming and securing, grain can shift in heavy weather and produce significant transverse heeling moments that may exceed the vessel’s righting capacity. Multiple grain ship casualties through the early and mid twentieth century established the catastrophic potential of grain shifting; the Grain Code was developed to systematically prevent these losses.
The Grain Code requires:
- Hold trimming: the cargo surface must be levelled to minimise initial cargo voids.
- Shifting boards or feeders: longitudinal partitions extending into the cargo void above the trimmed surface, supported on the underdeck structure, that reduce the lateral grain volume free to shift.
- Stability calculations: each loaded condition must be analysed for assumed grain heeling moment and the vessel’s residual righting capacity. The stability calculation uses standard heeling moment values from the Grain Code based on hold geometry and loading pattern.
- Authorised loading conditions: the master must load the vessel within a documented authorised condition derived from the stability calculation and the Grain Code’s heeling moment provisions.
Cargo handling concerns
Beyond shifting prevention, wheat presents:
- Self-heating risk: if the moisture content is elevated (above approximately 15 per cent), microbial activity in the grain can release heat, causing temperature rise and grain spoilage. Pre-loading certification of moisture content is standard, and grain that is excessively wet is rejected.
- Insect infestation: weevils, grain beetles, and similar pests can colonise grain cargoes. Many shipments are fumigated with phosphine or methyl bromide before or during voyage. Phosphine fumigation is performed in sealed holds with monitoring; the master must verify fumigation procedures and crew safety.
- Dust explosion risk: grain dust in confined handling spaces is combustible and presents an ignition risk during loading and discharge. Dust suppression is standard practice.
- Compatibility with subsequent cargoes: grain residues must be thoroughly cleaned from holds before loading any subsequent cargo, particularly to prevent contamination concerns from prior cargoes. Hold preparation for grain after coal, fertilizer, or other dirty cargoes requires comprehensive cleaning, washing, and inspection.
Major routes
Wheat seaborne trade flows include:
- Russia to North Africa, Middle East, and Sub-Saharan Africa: the dominant flow since approximately 2017, with Black Sea ports (Novorossiysk, Tuapse, Yeisk) supplying Egypt, Türkiye, and other Mediterranean markets.
- United States to Latin America, North Africa, and Asia: Pacific Northwest (Portland, Seattle), Gulf (New Orleans, Galveston), and Atlantic export.
- Canada to global markets: principally Pacific export through Vancouver and Prince Rupert, plus East Coast and Great Lakes export.
- Argentina to Brazil, Africa, and Asia: Bahía Blanca and Rosario export.
- Australia to Southeast Asia, Middle East, and Africa: Newcastle, Geraldton, and Western Australian export.
- European Union to North Africa: French and German Atlantic and Mediterranean export.
- Ukraine to global markets: Odesa and Black Sea exports, severely disrupted since 2022 but partially restored through humanitarian corridors.
Egypt is the world’s largest single wheat importer, accounting for approximately 12 to 13 million tonnes per year (subject to substantial year-on-year variation), with imports principally from Russia and Ukraine.
Loading and discharge
Loading is by shore conveyor and shiploader at major grain export terminals. Loading rates of 2,000 to 6,000 tonnes per hour are typical at the largest terminals. Hold preparation includes comprehensive cleaning, drying, and inspection per the Grain Code provisions. Trimming and shifting board installation are completed before hatch closure.
Discharge is by grab-fitted shore cranes, pneumatic vacuum unloaders, or screw augers at receiving grain terminals. Some major importing ports (Alexandria, Damietta, Antwerp, Rotterdam) operate dedicated grain terminals with multiple silos and rapid discharge capabilities.