Rock Phosphate Cargo Stowage Factor: Bulk Shipping

Rock phosphate moves in massive volumes across the world's oceans, yet the single number that determines how much fits in a hold, the stowage factor, shifts with every grade and moisture point. Getting that figure wrong triggers deadfreight claims, stability breaches, and demurrage disputes that cost owners and charterers thousands of dollars per day. This guide delivers the definitive stowage factor ranges for every commercial grade, the dual-unit conversion tables fixture negotiators need, and the IMSBC Code compliance framework that governs declarations, testing, and hold preparation.

You will learn how moisture content tightens the stow by up to 0.05 cubic metres per tonne, why grain clean holds and cement-washed bilge wells are non-negotiable, and how angle of repose values drive trimming requirements under the Code. The article covers loading sequences for Supramax and Panamax stability, voyage ventilation rules that prevent caking, and dust control obligations at discharge ports from Casablanca to Aqaba. It closes with charter party clause breakdowns on stowage factor warranties, trimming liability, and weather working day definitions that protect your laytime.

Rock Phosphate Stowage Factor: Definitive Values & Conversion Tables

The stowage factor of rock phosphate ranges from 32 to 38 cubic feet per long ton which converts to 0.90 to 1.07 cubic metres per tonne depending on grade and moisture content. Low grade material with higher gangue content typically occupies the upper end of the range near 38 cubic feet per long ton or 1.07 cubic metres per tonne. High grade concentrate with lower impurities settles closer to 32 cubic feet per long ton or 0.90 cubic metres per tonne. Moisture increases bulk density so a cargo at 12 percent moisture will stow tighter than the same grade at 4 percent moisture. Global production of phosphate rock in 2024 stood at 209 mt according to PhosAgro Annual Report 2024 which underscores the volume of cargo moving under these parameters.

Stowage factor range for low-grade vs high-grade rock phosphate

Low grade rock phosphate typically exhibits a stowage factor between 36 and 38 cubic feet per long ton equivalent to 1.01 to 1.07 cubic metres per tonne. High grade rock phosphate generally falls between 32 and 34 cubic feet per long ton equivalent to 0.90 to 0.96 cubic metres per tonne. The difference stems from particle size distribution and impurity levels which affect void space between granules. Charter party warranties usually reference a single figure so shippers and receivers must agree which grade applies before fixture.

Dual-unit conversion table (cu ft/ton to m3/tonne)

Grade Description	Stowage Factor (cu ft/long ton)	Stowage Factor (m³/tonne)	Typical Moisture Range (%)	Bulk Density (t/m³)
High Grade Concentrate	32 - 34	0.90 - 0.96	3 - 6	1.04 - 1.11
Standard Merchant Grade	34 - 36	0.96 - 1.01	5 - 8	0.99 - 1.04
Low Grade / High Impurity	36 - 38	1.01 - 1.07	8 - 12	0.93 - 0.99

The table above shows the three common grade bands used in fixture negotiations. Use the cubic metre per tonne column for metric tonnage calculations and the cubic foot per long ton column for traditional charter party clauses. Bulk density is the reciprocal of the metric stowage factor and is useful for hold cubic capacity checks.

Impact of moisture content on volumetric weight

Moisture content directly reduces the stowage factor because water fills voids between particles increasing bulk density. A cargo at 12 percent moisture can stow up to 0.05 cubic metres per tonne tighter than the same cargo at 4 percent moisture. This variation matters when a vessel is cubic limited rather than deadweight limited. Always confirm the moisture basis of the declared stowage factor on the shipper declaration to avoid intake disputes.

IMSBC Code Compliance: Classification, Certificates & Testing Requirements

Rock phosphate is classified under the IMSBC Code as Group C cargo which means it is not liable to liquefy and does not possess chemical hazards. The schedule requires a shipper declaration confirming the cargo is not a concentrate likely to liquefy and stating the moisture content and transportable moisture limit. A moisture certificate issued within seven days of loading is mandatory. The transportable moisture limit must be determined by the modified Proctor test or flow table test as specified in Appendix 2 of the Code. Sampling must follow the procedures in Section 4.3 of the Code to ensure representative results.

IMSBC Group C classification and schedule references

Rock phosphate appears in the IMSBC Code under the individual schedule for Phosphate Rock which assigns it to Group C. Group C cargoes are those which are neither liable to liquefy (Group A) nor possess chemical hazards (Group B). The schedule notes that certain fine concentrates may exhibit Group A behaviour so the shipper must declare the cargo type accurately. Reference the latest edition of the Code and the supplement for any amendments to the schedule text or test methods.

Shipper's declaration: moisture certificate and stowage factor warranty

The shipper must provide a signed declaration before loading that includes the cargo description the moisture content the transportable moisture limit and the stowage factor. The moisture certificate must be issued by an entity accepted by the competent authority of the port of loading and dated within seven days of the commencement of loading. The stowage factor declared becomes the warranty used in the charter party for intake calculations. Any discrepancy between the declared figure and the actual stowage observed during loading can trigger a claim for deadfreight or short loading.

TML testing procedures and sampling standards

The transportable moisture limit for rock phosphate is determined using the modified Proctor test as described in Appendix 2 of the IMSBC Code. The flow table test is an alternative method but the modified Proctor is preferred for this cargo. Samples must be taken from throughout the stockpile in accordance with Section 4.3 of the Code to produce a representative composite sample. The test report must state the TML value the moisture content at the time of testing and the laboratory accreditation details. Masters should verify the TML certificate is valid and matches the cargo presented at the quay.

Hold Preparation & Cleanliness Standards for Phosphate Rock

Cleanliness standards: grain clean vs hospital clean requirements

Rock phosphate requires holds to meet grain clean standard as a minimum which means all loose scale rust and previous cargo residues must be removed so that no visible contamination remains on bulkheads or tank tops. Hospital clean is only specified when the charter party demands it for premium grade cargoes or when the next cargo after phosphate is sensitive to phosphate dust. Sweeping and vacuuming of hatch coamings and bracket toes is essential because phosphate dust settles in these areas and can contaminate subsequent grain or fertilizer cargoes. A final visual inspection by the master and a surveyor if appointed confirms the standard before loading commences.

Bilge well protection and cement washing procedures

Bilge wells must be cleaned dry and coated with a cement wash or lime wash to prevent phosphate fines from entering the bilge system where they can harden and block suctions or damage pumps. The wash is applied to the well plating and the top of the strainer plate forming a sacrificial layer that can be washed out after discharge. Any existing cement wash from previous voyages must be inspected for cracks and reapplied if necessary. Scuppers and non-return valves are tested for tightness because phosphate slurry can escape to deck and cause environmental claims in port.

Contamination risks from coal, iron ore, and fertilizer residues

Residual coal dust is a primary contamination risk because it discolours the phosphate and introduces sulphur and carbon that affect downstream acidulation plant chemistry. Iron ore fines stain the cargo red and increase the iron oxide content beyond buyer specifications. Fertilizer residues such as urea or DAP create localized moisture hotspots that can initiate caking in the phosphate cargo. Global production of complex phosphate-based fertilizers (DAP + MAP) reached 61.2 mt in 2024 according to PhosAgro Annual Report 2024 which increases the likelihood of cross contamination in multi cargo vessels. A written cleaning declaration signed by the master and the stevedore superintendent records the previous three cargoes and the cleaning method used.

Loading, Trimming & Stability Management

Angle of repose values and trimming requirements per IMSBC

The angle of repose for rock phosphate ranges from 32 to 38 degrees depending on particle size distribution and moisture content. The IMSBC Code requires trimming to reduce the angle of the cargo surface to 25 degrees or less within the hatch coaming boundaries to minimize shifting risk. Trimming is typically achieved by spout trimming during loading or by bulldozer and bobcat operations after each pour. The master must ensure the final surface is reasonably level and that no peaks remain near hatch corners where shifting can initiate.

Loading sequences for even weight distribution

Loading sequences follow the vessel loading plan agreed between the master and the terminal to maintain hull girder stresses within allowable limits. For a typical Supramax the sequence often starts with the midship holds then alternates forward and aft holds to control shear force and bending moment. The terminal pour plan must respect the maximum allowable load per hold and the maximum double bottom tank filling sequence. Real time loading instrument readings are monitored continuously and any deviation from the plan is corrected before the next pour commences.

Stability calculations: GM requirements and free surface effect

Intact stability must meet the IMO Code on Intact Stability criteria with a minimum GM of 0.3 metres at departure after correcting for free surface effect in slack tanks. The free surface correction is significant when double bottom ballast tanks are partially filled during loading. The cargo vertical centre of gravity is calculated using the declared stowage factor and the trim level achieved. The master verifies that the departure condition satisfies the area under the GZ curve requirements and that the equilibrium angle in the event of a cargo shift does not exceed the angle of deck edge immersion.

Voyage Management: Ventilation, Moisture Control & Monitoring

Ventilation requirements: surface vs mechanical per IMSBC schedule

Rock phosphate is classified as a Group C cargo under the IMSBC Code and does not require mechanical ventilation during voyage. Surface ventilation through natural airflow is sufficient because the cargo does not emit toxic or flammable gases and does not self-heat. The holds should remain sealed during heavy weather to prevent seawater ingress which can trigger caking. Masters should verify that ventilation covers are operational and that the cargo surface is trimmed reasonably level to allow air circulation above the stow. If the cargo was loaded with a moisture content above the transportable moisture limit the master must seek specialist advice because standard ventilation will not remediate excess moisture.

Temperature and moisture monitoring logs during transit

Daily temperature readings are taken at three depths in each hold using sounding pipes or probe access points and recorded in the cargo log. Ambient temperature and humidity are logged simultaneously to establish a baseline. A steady rise in cargo temperature above ambient by more than five degrees Celsius may indicate localized moisture migration or the onset of caking. Moisture content is not routinely tested at sea but the master should request a shore side analysis if temperature anomalies persist. All readings are timestamped and retained for the voyage record to support any future claim investigation.

Caking and hardening risk mitigation strategies

Caking occurs when moisture dissolves soluble salts in the rock phosphate which then recrystallize binding particles into a solid mass. The risk increases with finer particle size higher moisture content and prolonged voyage duration. To mitigate this the cargo should be trimmed flat to reduce surface area exposed to condensation. Hatch covers must be weathertight and double bottom tanks adjacent to loaded holds should be kept empty or pressed up to minimize temperature differentials. If caking is encountered at discharge the terminal uses excavators or mechanical breakers and the charter party typically addresses the additional time and cost through specific clauses.

Discharge Operations, Dust Control & Port Restrictions

Dust control measures: water sprays dust suppression systems

Dust generation during discharge is controlled by fixed or mobile water spray systems at the discharge terminal. Grab cranes and conveyor transfer points are fitted with misting nozzles that activate automatically when material passes. The ship's crew assists by wetting the cargo surface in the hold before each grab cycle using deck fire hoses or installed spray lines. Excessive water must be avoided because it increases the moisture content of the remaining cargo and can create slurry in the bilges. Terminal environmental permits typically set opacity limits for visible dust plumes and continuous monitoring stations record compliance.

Port draft restrictions at Casablanca Jorf Lasfar Aqaba Safaga

Major load ports impose draft limits that dictate the maximum parcel size for each vessel class. Casablanca and Jorf Lasfar in Morocco generally accommodate Panamax vessels at 12.5 to 13.5 metres draft depending on the berth and tide. Aqaba in Jordan is restricted to approximately 12.0 metres limiting intake to Supramax or Handymax tonnages. Safaga in Egypt has a controlling depth near 11.5 metres favouring Handysize vessels. Masters must confirm the latest hydrographic data and port authority circulars before finalizing the stowage plan because seasonal siltation or dredging cycles change the allowable draft.

Environmental regulations for phosphate dust emissions

Phosphate dust is classified as a nuisance particulate and is regulated under national air quality standards in most discharge jurisdictions. The European Union applies ambient air quality directives that set limit values for PM10 and PM2.5 concentrations at the port boundary. In the United States the Clean Air Act requires state implementation plans that include fugitive dust control plans for bulk terminals. Morocco and Jordan enforce similar standards through their respective environment ministries. Non compliance can result in terminal fines vessel detention or suspension of operating permits. Charter parties should allocate responsibility for dust suppression costs and delays caused by environmental stoppages.

Charter Party Clauses: SF Warranties, Trimming & Demurrage

Stowage factor warranty clauses and shortage claim triggers

Charter parties for rock phosphate routinely include a stowage factor warranty expressed in cubic metres per tonne that binds the charterer to the cargo's physical characteristics. If the actual stowage factor exceeds the warranted figure the vessel reaches its volumetric capacity before achieving the agreed deadweight intake creating a shortage claim. The clause typically triggers a financial penalty calculated as the difference between the bill of lading quantity and the maximum intake at the warranted factor multiplied by the freight rate. Owners should verify that the warranty references the specific test method used by the shipper such as the IMSBC Code appendix or ISO 3852 because different methods yield materially different results. A warranty without a defined test basis exposes the owner to disputes over whether the cargo or the measurement standard caused the shortfall.

Trimming responsibilities: charterer vs owner obligations

Trimming terms determine who pays for and directs the leveling of cargo within the holds to ensure stability and maximum intake. Under FIOST terms the charterer arranges and pays for trimming while FIOS requires the owner to trim at charterer's expense. The charter party should specify the required angle of repose compliance typically 35 degrees for rock phosphate and whether mechanical trimming or manual labor is acceptable. Port customs often dictate the method; for example some North African terminals prohibit shore based dozers from entering holds requiring vessel gear or floating cranes instead. The clause must allocate liability for damage to tank tops or hatch coamings during trimming operations and state whether trimming time counts as laytime or is excluded.

Weather working days definitions and demurrage rate structures

Laytime definitions for rock phosphate must address the cargo's moisture sensitivity because rain halts loading and discharging to prevent free moisture accumulation. A weather working day clause typically states that time lost due to rain counts as laytime only if the vessel is ready to work and the terminal operates; otherwise it is excluded. Demurrage rates for Supramax and Ultramax vessels on phosphate routes commonly range from twelve thousand to eighteen thousand US dollars per day pro rata. The charter party should clarify whether demurrage accrues during periods when the vessel is waiting for a berth due to draft restrictions at ports like Safaga or Aqaba. Dispatch provisions at half the demurrage rate are standard but owners should resist clauses that allow dispatch to offset demurrage across multiple ports.

Major Trade Routes, Parcel Sizes & Vessel Selection Guide

Major export ports: Casablanca, Jorf Lasfar, Aqaba, Safaga, Sfax

Casablanca and Jorf Lasfar in Morocco dominate global rock phosphate exports handling the largest parcel sizes with modern shiploaders and deep drafts up to 14.5 metres. Aqaba in Jordan serves the Middle Eastern and Asian markets with a draft restriction near 12.0 metres limiting vessels to Supramax class. Safaga in Egypt operates at approximately 11.5 metres draft favouring Handysize vessels for intra Mediterranean and Red Sea trades. Sfax in Tunisia handles smaller parcels typically twenty five thousand to thirty five thousand tonnes for European fertilizer plants. Each port applies unique stockpile management and loading rate guarantees that charter parties must reflect to avoid demurrage disputes.

Import destinations: India, Brazil, Europe, USA parcel sizes

India receives the largest volume of rock phosphate imports with parcel sizes frequently exceeding fifty five thousand tonnes destined for fertilizer complexes on the east and west coasts. Brazil imports substantial volumes for its agricultural sector typically in forty thousand to fifty thousand tonne parcels discharged at ports like Paranagua and Santos. European destinations including Rotterdam, Antwerp and Hamburg handle smaller lots of twenty thousand to thirty five thousand tonnes for niche phosphate feed and acid production. The United States imports via Tampa and New Orleans in thirty thousand to forty five thousand tonne parcels for domestic phosphoric acid plants. Vessel selection must match the discharge port draft and unloader capacity to avoid partial discharge and costly lightering.

Vessel suitability: Handysize, Supramax, Ultramax, Panamax selection criteria

Handysize vessels of twenty eight thousand to thirty eight thousand deadweight tonnes suit Safaga Sfax and smaller Tunisian or Egyptian ports with draft limits below twelve metres. Supramax vessels of fifty two thousand to fifty eight thousand deadweight tonnes are the workhorse for Aqaba Jorf Lasfar and Indian east coast ports balancing draft and gear flexibility. Ultramax vessels of sixty thousand to sixty four thousand deadweight tonnes maximize intake at Jorf Lasfar and Casablanca where draft permits and offer higher daily earnings on longer hauls to Brazil. Panamax vessels of seventy five thousand to eighty two thousand deadweight tonnes serve deep water terminals in Morocco and the US Gulf but require careful stowage planning due to hold geometry. The table below summarizes the key selection parameters.

Vessel Class	DWT Range (tonnes)	Typical Intake Rock Phosphate (tonnes)	Key Loading Ports	Key Discharge Regions	Gear Configuration
Handysize	28,000, 38,000	25,000, 35,000	Safaga, Sfax, Annaba	Mediterranean, Red Sea, West Africa	Cranes 30t SWL
Supramax	52,000, 58,000	48,000, 54,000	Aqaba, Jorf Lasfar, Casablanca	India, Brazil, Europe, US Gulf	Cranes 30, 36t SWL
Ultramax	60,000, 64,000	55,000, 60,000	Jorf Lasfar, Casablanca	India, Brazil, US Gulf	Cranes 30, 36t SWL
Panamax	75,000, 82,000	70,000, 77,000	Jorf Lasfar, Casablanca	US Gulf, Brazil, North Europe	Gearless

The table matches vessel deadweight to realistic rock phosphate intake using a stowage factor of 0.85 to 0.95 cubic metres per tonne and typical port draft limits. Handysize vessels achieve full deadweight utilization only at the lightest stowage factors while Supramax and Ultramax classes frequently hit volumetric limits before reaching their marks. Panamax vessels require the deepest berths at Jorf Lasfar or Casablanca to load full parcels and are restricted to gearless discharge terminals. Charterers should select the smallest class that meets the parcel size to minimize freight per tonne and reduce exposure to draft restrictions at discharge ports.

Worked Example: Calculating Maximum Intake for a Supramax Vessel

Vessel cubic capacity determination from capacity plan

The capacity plan provides the total grain or bale cubic capacity for each hold which is the starting point for any intake calculation. For a typical 56,000 DWT Supramax the five holds usually offer a combined grain capacity of approximately 70,000 cubic metres. This figure represents the absolute volumetric limit before any broken stowage or structural obstructions are considered. The master must verify the capacity plan against the vessel's specific general arrangement because hatch coaming height and bilge well volume can reduce usable space by several hundred cubic metres. Accurate cubic data prevents overbooking which leads to last minute cargo rejection at the load port.

Calculation: hold capacity divided by stowage factor equals max tonnes

Dividing the total hold capacity by the cargo stowage factor yields the maximum volumetric tonnage the vessel can accommodate. Using a rock phosphate stowage factor of 0.90 cubic metres per tonne the calculation is 70,000 divided by 0.90. However the vessel deadweight of 56,000 tonnes minus constants such as fuel water stores and crew typically leaves a cargo deadweight that governs the maximum intake. The charter party must reflect the lower of the two limits to avoid disputes over short loading or deadfreight claims.

Deadweight and draft constraint verification

The final step confirms that the calculated tonnage complies with load line and port draft restrictions at both load and discharge berths. A Supramax loaded to its available cargo deadweight of rock phosphate will typically sit at a mean draft of 12.8 metres in salt water. If the load port such as Jorf Lasfar allows 13.0 metres and the discharge port in Brazil allows 13.5 metres the vessel can sail fully laden. If the discharge port restricts draft to 12.5 metres the master must reduce the cargo to comply. Global dry bulk seaborne trade exceeded 5.6bn MT of cargo in 2024, a first according to AXSMarine highlighting the volume of cargo moving under similar draft constraints worldwide. The voyage instructions should always specify the limiting draft for each port in the rotation.

Parameter	Value	Unit	Constraint Type
Vessel Deadweight (DWT)	56,000	MT	Structural
Constants (Fuel, Water, Stores)	3,500	MT	Operational
Available Cargo Deadweight	52,500	MT	Weight Limit
Total Hold Capacity (Grain)	70,000	m³	Volumetric
Rock Phosphate Stowage Factor	0.90	m³/MT	Cargo Property
Volumetric Capacity	77,778	MT	Volume Limit
Maximum Intake (Limiting Factor)	52,500	MT	Deadweight Limited

The table above summarizes the intake calculation for a standard 56,000 DWT Supramax. The available cargo deadweight is the limiting factor because the volumetric capacity exceeds the weight the vessel can legally carry. Operators must always compare the deadweight limit against the volumetric limit using the specific stowage factor declared on the shipper's certificate. A higher stowage factor would reduce volumetric capacity but the deadweight would remain the governing constraint. This comparison ensures the fixture reflects the true maximum quantity the vessel can lift on the intended route.

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Related reading: Incoterms 2020: DDP vs DAP for Importers, Urea Price Chart 2026: Historical Data, Trends and News.

Conclusion

Successful rock phosphate bulk shipping operations depend on rigorous adherence to the IMSBC Code from the moment a fixture is negotiated until the final hold is signed clean. Accurate stowage factor application ensures the vessel reaches its deadweight or cubic capacity limit without dangerous overloading or costly broken stowage. Hold preparation that meets the cleanliness standard appropriate to the cargo grade prevents contamination claims that routinely exceed the value of the cargo itself. Loading and trimming plans must be agreed with the terminal in writing and executed to maintain stability criteria at every stage of the voyage. Ventilation strategy, fixed before departure and logged daily, controls the moisture migration that drives caking and weight disputes. At the discharge port, pre-arrival coordination on dust suppression, gear readiness and surveyor appointments converts potential demurrage days into efficient turnaround. Charter party clauses governing stowage factor warranties, trimming obligations and demurrage thresholds must reflect the physical realities of the trade rather than generic boilerplate. Documentation discipline across bills of lading, mate's receipts, certificates of origin and the official logbook creates the evidentiary chain that resolves disputes before they reach arbitration. Operators who embed these practices into standard operating procedures protect both the cargo and the commercial relationship.

Frequently Asked Questions

What is the stowage factor of rock phosphate in cubic feet per ton?

The stowage factor ranges from 32 to 38 cubic feet per long ton depending on grade and moisture content. High grade concentrate typically occupies 32 to 34 cubic feet while low grade material with higher impurities requires 36 to 38 cubic feet. Charter parties must specify the applicable grade to avoid intake disputes.

What is the stowage factor of rock phosphate in cubic meters per tonne?

The metric stowage factor ranges from 0.90 to 1.07 cubic metres per tonne across the three common grade bands. High grade concentrate falls between 0.90 and 0.96 while low grade ranges from 1.01 to 1.07 cubic metres per tonne. Use these figures for deadweight and cubic capacity calculations in metric fixtures.

What is the IMSBC code classification for rock phosphate?

Rock phosphate is classified as a Group C cargo under the IMSBC Code meaning it is not liable to liquefy and possesses no chemical hazards. The individual schedule for Phosphate Rock requires a shipper declaration confirming the cargo type and moisture parameters. Certain fine concentrates may exhibit Group A behaviour so accurate declaration is mandatory.

What is the angle of repose for rock phosphate?

The angle of repose ranges from 32 to 38 degrees depending on particle size distribution and moisture content. The IMSBC Code requires trimming the cargo surface to 25 degrees or less within hatch coaming boundaries to minimize shifting risk. Trimming is typically achieved by spout trimming during loading or by bulldozer operations after each pour.

Does rock phosphate require ventilation during voyage?

No mechanical ventilation is required during voyage because rock phosphate is a Group C cargo that does not emit toxic or flammable gases. Surface ventilation through natural airflow is sufficient provided the cargo surface is trimmed reasonably level. Holds must remain sealed during heavy weather to prevent seawater ingress which can trigger caking.

What are the hold cleaning requirements for rock phosphate?

Holds must meet grain clean standard as a minimum with all loose scale rust and previous cargo residues removed. Bilge wells require cleaning and coating with cement wash or lime wash to prevent phosphate fines from hardening in the bilge system. Hospital clean is only required when specified in the charter party for premium grades or sensitive subsequent cargoes.

What is the typical moisture content of rock phosphate?

Typical moisture content ranges from 3 to 12 percent depending on grade with high grade concentrate at 3 to 6 percent and low grade at 8 to 12 percent. Moisture directly affects bulk density and stowage factor so the shipper declaration must state the moisture basis used. A moisture certificate issued within seven days of loading is mandatory under the IMSBC Code.

What are the major export ports for rock phosphate?

Major export ports include Casablanca and Jorf Lasfar in Morocco, Tampa and Port Sutton in the USA, Phalaborwa via Richards Bay in South Africa, and various ports in Jordan, Egypt and Peru. Port selection depends on the mine origin and the receiving region trade lane. Terminal facilities at these ports typically offer high capacity loading rates for bulk carriers.

What vessel sizes are used for rock phosphate shipping?

Handysize and Supramax vessels dominate the trade due to port draft restrictions at many loading and discharge terminals. Panamax vessels are common on longer haul routes from Morocco or the Middle East to Asia. Capesize vessels are rarely used except for dedicated high volume contracts between deep water terminals.

How does rock phosphate stowage factor compare to DAP and MAP?

Rock phosphate has a higher stowage factor than processed fertilizers with DAP and MAP typically stowing between 0.75 and 0.85 cubic metres per tonne. The lower bulk density of rock phosphate means a vessel reaches cubic capacity before deadweight limit more often than with DAP or MAP. This difference affects freight calculations on cubic limited voyages.

What causes shortage claims in rock phosphate shipments?

Shortage claims typically arise from discrepancies between the declared stowage factor and actual intake during loading. Moisture loss during transit, scale errors at the load port, and cargo remaining in holds after discharge also contribute. Accurate shipper declarations and joint draft surveys at both ports reduce the frequency of these disputes.

What certificates are required before loading rock phosphate?

A shipper declaration stating the cargo description, moisture content, transportable moisture limit and stowage factor is required before loading. A moisture certificate issued within seven days of loading by an entity accepted by the competent authority is mandatory. The TML certificate must reference the modified Proctor test or flow table test method used.

Sources

• PhosAgro Annual Report 2024 (2024): Global phosphate rock production
• AXSMarine (2024): Global dry bulk seaborne trade