A reefer vessel is a specialised refrigerated cargo ship designed to carry palletised or loose perishable goods in insulated, mechanically cooled cargo spaces. Unlike standard container ships that carry individual refrigerated containers (each with its own genset or ship power connection), traditional reefer vessels provide centralised controlled-temperature holds with integrated refrigeration plant, tighter ambient control and design features for efficient handling of palletised loads. Modern shipping uses both concepts: many perishable shipments now move as containerised reefers on container ships for flexibility, while dedicated reefer ships still serve niche trades requiring intensive cargo care or large-volume single-commodity movements. Reference
Dedicated reefer ships offer centralised, high-capacity refrigeration, tailor-made stowage, and often gentler cargo handling for fragile, high-value perishables. They can integrate features like water-cooled machinery, well-designed ventilation, and inspection access. Containerised reefers, however, give unmatched flexibility, intermodal compatibility and scale economies, letting shippers use standard container logistics. The limitation of reefers-on-containers is the need for many individual power connections and more frequent inspection of each unit, while dedicated reefer tonnage is declining and less flexible for mixed-cargo itineraries. Choice depends on commodity, route, and supply-chain needs. Reference
Reefer containers are stowed following ship-specific cargo plans that consider access for inspection, ventilation, power supply lines and the ship’s structural securing points. On exposed decks, they are lashed and secured with rods and twistlocks; underdeck stowage uses cell guides or cargo holds with walkways for inspection. Position matters because exposure (sun/wind), available power sockets, water-cooling provision, access for maintenance and safe inspection all vary by location — and incorrect stowage can hinder monitoring or prolong corrective action if a container alarms. International stowage guidance helps planners select positions that balance safety and cargo care. Reference
Containers stowed on the open deck are normally air-cooled by their own refrigeration units and inspected regularly, while those stowed under deck may rely on shipboard water-cooling systems to reject heat from the container’s condenser. Under-deck water cooling permits a higher density of reefers below deck and helps reduce external weather exposure, but requires penetration of power and cooling services and access routes for inspection. Each option affects ventilation, heat rejection capacity, inspection routines, and how alarms or faults are handled during the voyage. Reference
Monitoring combines onboard manual checks with telemetric systems that log setpoints, cargo temperature probes and alarm events. Crews perform regular rounds to visually inspect units, confirm correct controls and note condensation or power faults, while many operators now use remote container monitoring (telemetry) to send temperature, setpoint and alarm data ashore in near real time. Effective monitoring requires disciplined watch schedules, clear alarm escalation procedures and documented responses so excursions are quickly detected, diagnosed and corrected to protect cargo integrity. Reference
Common failures include loss of power (ship supply or genset), condensation or blocked fans, refrigerant faults, control/sensor failures and sea-spray corrosion. Emergency procedures prioritise safe power isolation/transfer, switching to spare sockets or backup gensets, manual temperature checks of cargo cores, isolating malfunctioning units, and, if necessary, segregation or transhipment at the next port. Prompt logging, notifying operators/charterers and following the ship’s cargo plan and the container owner’s instructions are essential to limit damage and insurance exposure. Reference
Management combines correct setpoints, appropriate defrost scheduling, adequate airflow around the container and routine inspection for blocked drains or compromised seals. Poor ventilation and blocked airflow create condensation and mould risk, so stowage must allow air circulation and drainage. Crews should verify defrost cycles work, check water trays and drains, and respond to alarm conditions indicating high humidity or icing. Maintaining seals, preventing seawater intrusion and ensuring condensate drains are functioning are routine preventive steps against moisture-related cargo losses. Reference
Segregation is governed by cargo characteristics and the ship’s cargo plan: ethylene-producing fruits (bananas, apples) are separated from ethylene-sensitive items, odour-sensitive products are segregated from pungent goods, and incompatible commodities (e.g., fish and fruit) are kept apart. Proper ventilation, sealed packaging and avoiding mixed loading on adjacent tiers reduce cross-contamination. Documentation, labels and the shipper’s declarations are used to plan compatible stowage and ensure vents, temperature and atmospheric controls suit all cargoes in a block. Reference
To carry many reefers, a vessel needs sufficient dedicated electrical circuits or shore/ship-generated power, adequate distribution panels and spare outlets, and, if carrying reefers under deck, water-cooling or enhanced heat-exchange capability. Ships designed for reefers include dedicated reefer switchboards, monitoring panels, inspection walkways and sometimes redundant power feeds; planners must ensure load capacity, generator rating and distribution protection match the planned reefer fleet. Without this, overloading or insufficient cooling capacity causes alarms and cargo risk. Reference
Crew must be trained in reefer operation, alarm interpretation, contingency actions, electrical safety around multiple powered units and correct inspection routines. The ship’s cargo manual should detail stowage, securing, power arrangements, inspection frequency and emergency response. Responsibilities typically include daily checklist completion, logging temperatures, carrying spare leads and adaptors, and liaising with container operators. Regulatory guidance (ISM/IMO) and cargo-securing manuals require documented procedures and competence to reduce risk and support claims handling if loss occurs. Reference
Ships carrying reefers maintain a stock of compatible outlets, extension leads and adaptors, and keep a register of plug types and socket locations. Crews must inspect plugs and leads for corrosion or damage, label and test spare leads, and ensure the power panel’s breakers and wiring are properly rated. Before loading, compatibility checks between container plugs and ship sockets prevent unsafe connections; carrying spare leads and adaptors is industry best practice to ensure continuity if a socket fails. Reference
Rough seas increase the risk of lashings failing and of containers shifting, which can damage refrigeration equipment or sever power leads; humidity and ambient heat influence refrigeration load and defrost frequency; long voyages increase cumulative risk of small faults turning into losses. Voyage planning, therefore, includes selecting protected stowage for sensitive loads where possible, increasing inspection frequency during heavy weather, confirming lashings after severe conditions and adjusting setpoints/defrost cycles to match ambient exposure and voyage length. Reference
Remote telemetry provides continuous logging of temperatures, alarms and setpoint changes and allows shore-side operators to triage alarms, advise the crew and, in some systems, change setpoints. This capability improves situational awareness, shortens response times and helps document conditions for claims or quality assurance. However, telemetry depends on reliable onboard infrastructure and agreed escalation procedures so that shore-side decisions are actionable and aligned with the ship’s operational constraints.
Biosecurity and fumigation are tightly regulated: shippers must declare fumigated goods and provide certificates, containers must be ventilated as required, and certain commodities trigger phytosanitary inspections at destination. Proper documentation (temperature logs, pre-shipment checks, fumigation certificates) and adherence to quarantine rules reduce the risk of cargo rejection, delays or fines. Crews and operators must follow port and flag-state rules and ensure records are available for inspection. Reference
Pre-voyage checks include verifying container setpoints, testing power plug compatibility and socket condition, confirming alarm systems and telemetry, inspecting door seals and drains, checking refrigerant and fan operation, and recording cargo-specific instructions and certificates. A clear handover between the terminal and ship with signed checklists, temperature logs and confirmation of spare leads/adaptors reduces misunderstandings and supports fast corrective action if a problem arises during the voyage. Documentation should be retained for claims or quality traceability. Reference
Designed for container terminal environments, Reefer Runner is a wireless plug-and-play system enabling complete reefer monitoring and management. It streams real-time data on temperature, power supply, energy usage, alarms and performance into a dashboard integrated with the TOS. The technology enhances situational awareness, cuts manual routines, lowers damage and claim risks, improves safety and supports compliant operations.
Reefer Runner by Identec Solutions
Most container vessels supply reefer containers with three-phase AC power. Classification societies (e.g., LR) note that the typical onboard distribution for reefer sockets is 440 V (or 460 V) at either 50 Hz or 60 Hz, depending on ship design. The variant depends on the ship’s generation system (diesel or shaft generators) and how the main switchboard is configured. Reference
The ship must have dedicated feeder circuits and sufficient generator capacity to power all planned reefer sockets plus the vessel’s essential services. According to classification rules, even with one generator offline, the remaining machinery must sustain full reefer load and ventilation systems. Without adequate capacity, the ship risks overload, blackouts, or failures in maintaining reefer cargo temperature. Reference
Reefer containers consume significant power. According to IMO-aligned design guidance, a 20-ft reefer with frozen cargo may draw around 5.5 kW, whereas a 40-ft unit may require 8.5 kW under normal operation once cool-down has been achieved. These values inform how large the onboard power distribution and socket network must be dimensioned. Reference
Ships generally use IEC/CEE 32 A plugs, matched to ISO-standard reefer container leads. These plugs are designed to handle three-phase current and provide a reliable, lockable connection that’s resistant to marine conditions. Reference
Reefer socket outlets installed on deck are typically certified for harsh marine environments: they are interlocked to prevent plugging/unplugging under load, rated for 480 V or more, and have IP67 weatherproof housings to protect against corrosion and water ingress. These design features ensure safety and reliability in salt-spray and high-humidity conditions. Reference
Some ships use a medium-voltage busbar (e.g., 2–4 kV) when they carry very large numbers of reefers, because transforming that down to the typical container voltage reduces current and power losses. Local transformers then feed the standard 440/460 V power outlets for the container sockets. Reference
Regulatory and classification standards (e.g., LR) mandate a standby transformer for reefer sockets. This ensures that, in case of a transformer failure or if one power feeder is lost, there is still a path to deliver power to reefer containers. Reference
Best practices for reefer carriage call for ships to carry spare extension leads, plug adaptors, and spare sockets. This enables crews to quickly respond when plugs fail, sockets are damaged or incompatible, or when more reefers are loaded than initially planned. Reference
Reefer sockets should have upstream circuit breakers or fuses to protect against overcurrent or short circuits. Also, many plugs have interlock mechanisms so you cannot unplug under load, avoiding arcing and potential damage. Reference
When ships receive reefers with mismatched power requirements, they may need step-up or step-down transformers. Such transformers adjust the ship’s available voltage to match the reefer’s input requirement, ensuring compatibility without overloading. Reference
Crew should check the compatibility of plugs and sockets before loading, secure locking collars, inspect for corrosion, and verify that the unit powers up and reaches the setpoint after connection. Training also covers safe disconnection procedures, securing spare leads/adaptors, and managing alarms related to the power supply during the voyage. Reference
When a ship uses a shaft generator driven by the main engine, frequency can fluctuate with engine speed. To maintain a stable frequency (e.g., 60 Hz), the ship may need a frequency converter, but that can introduce harmonics, which may disturb sensitive reefer electronics. Designers must mitigate these effects to ensure the stable operation of reefer units. Reference
If shipboard power capacity is insufficient, freestanding power packs (often diesel-generator units in containers) can supply power to reefers. These packs can temporarily extend power capacity, ensuring reefers remain operational when shore power or ship generation is limited. Reference
Some reefers come with integrated diesel gensets, eliminating the need for ship power. However, their fuel capacity is limited, so they are primarily used in closed-loop trades or when power packs are impractical. Frequent monitoring is needed to ensure they do not run out of fuel mid-voyage. Reference
Ships should regularly inspect sockets for corrosion, check the tightness of electrical connections, test circuit protection devices, and verify interlock function. Crews should also inspect gear before each sailing, maintain spare leads/adaptors properly, and document power-connection history in logs. Preventive maintenance helps minimise power-related reefer failures during voyages and ensures safety in harsh marine conditions. Reference
If dependable and uncomplicated reefer monitoring matters to you, consider an automated platform that centralises all information on one dashboard. Reefer Runner provides a scalable and easy monitoring and management system tailored to your terminal.
Reefer Runner by Identec Solutions
Reefer cargo is especially sensitive to time, temperature, humidity, and environmental conditions. Route planning for reefers must therefore weigh not just distance and cost, but also temperature exposure windows, port infrastructure for reefer handling, guaranteed power availability, and weather risks that could affect the cold chain. Tools like voyage-planning software integrate weather, port laytimes, and risk of delays to minimise spoilage and maintain freshness. For perishable goods, even small delays can significantly reduce value, so optimising routes for speed, reliability, and cargo-care infrastructure is paramount. Reference
Weather forecasting is critical in reefer route optimisation. Forecasted storms, high seas or extreme temperatures can jeopardise cargo quality by forcing deviations, delaying port calls, or increasing energy consumption (e.g., more defrosting). By using advanced routing tools that incorporate up-to-date meteorological data, ship planners can avoid high-risk regions, adjust speed in advance, and ensure stable power and ventilation for reefers, thereby reducing the risk of cargo degradation. Reference
A two-level planning model separates strategic route and speed decisions (top level) from real-time stability and load constraints (bottom level). For reefers, this means planners can optimise for fuel and time (reducing cost) while simultaneously ensuring the vessel’s stability constraints (e.g., weight distribution, ballast) are met. Recent research shows that such models, when including carbon or emissions costs, allow operators to balance operational efficiency and cargo care under constraints of stability and structure. Reference
Verified Gross Mass (VGM) is vital for accurate stability calculations. If container weights (including reefers) are misdeclared, it can lead to improper ballasting, incorrect trim, or unstable loading conditions. For perishable cargo, if the weight is underestimated, that can compromise stability margins over a voyage and increase risk during heavy weather. Sophisticated loading computers rely on VGM to calculate optimal stowage, draft, and ballast to keep the ship safe and efficient. Reference
Stowage planning for reefers must align container weight, location, and destination with the ship’s structural and stability constraints. Planners use loading computer software (e.g., MACS3) to model metacentric height, shear, torsion, and to ensure that reefers (which may be high-value, heavy or fragile) are positioned for easy access and safe handling. By aligning stowage and stability planning, the ship reduces re-stows, minimises the risk of shifting in rough seas, and ensures that reefers remain in optimal positions for power and ventilation. Reference
Speeding up a voyage reduces transit time, which is positive for perishable cargo, but increases fuel consumption, raising costs and emissions. Conversely, slowing down saves fuel but prolongs exposure of the cargo to ambient conditions and potential temperature risk. Optimisation models factor in these trade-offs by finding “sweet spot” speeds that balance reefers’ temperature risk with fuel costs — especially under carbon-tax or emissions-cost regimes. Reference
When carbon taxes or emissions pricing are applied, the operational cost of a voyage increases with higher fuel consumption. For reefer vessels, this means that route and speed planning must explicitly account for CO₂ costs. Optimisation models that internalise carbon tax penalise faster, less efficient transits and favour slightly slower speeds or alternative routes, so long as they don't jeopardise cargo quality, thus aligning financial and environmental goals. Reference
Different perishables have varying respiration rates, gas emissions (e.g., ethylene), and sensitivity to humidity. These properties influence how long cargo can withstand longer voyages and how ventilation or controlled atmosphere must be managed. Route planners must therefore integrate cargo-specific carriage instructions (ventilation set-points, defrost cycles) into the overall voyage strategy so that environmental exposure over transit does not compromise quality or accelerate spoilage. Reference
Ballasting (taking on or discharging ballast water) is critical for maintaining safe trim and stability, especially as the ship’s load changes (e.g., reefers added, discharged). With heavy perishable cargo, unplanned or mis-calculated ballast adjustments can lead to unsafe stability conditions (e.g., low GM). Route optimisation must therefore coordinate with ballast planning and stability constraints in real-time, adjusting as necessary during the voyage, especially when changing load or consumption patterns. Reference
Recently, deep reinforcement learning methods have been applied to master stowage planning, which can dynamically adapt loading plans under demand uncertainty while respecting vessel stability constraints. Such AI-driven frameworks optimise for the most efficient layout, minimise re-stow risk, and respect stability margins, resulting in more adaptive, feasible container plans even for volatile reefer demand. Reference
Re-stowing reefers mid-voyage (e.g., due to a change in discharge port) risks palleting damage, container misalignment, and stability disruption. Planners mitigate this by ensuring the initial stowage plan allows for flexibility — placing reefers in positions that facilitate later re-stows, choosing route calls carefully, and matching discharge sequences to optimise port operations and minimise dangerous movements or shifting on deck. Reference
Real-time telemetry from reefer containers (temperature, set-points, alarms) can feed into shore-side decision systems and route-optimisation tools. By analysing telemetry trends, planners can adjust vessel speed or route to respond proactively to risk signals (e.g., rising internal temps) or environmental threats, thereby dynamically safeguarding cargo quality without sacrificing stability or scheduling. This requires robust IT integration and responsive decision protocols. Reference
Pre-cooling cargo before loading is a fundamental step for reefers. At optimal carriage temperature, perishable goods absorb less heat during loading, reducing stress on the refrigeration units during the initial transients of the voyage. This lowers the risk of “pull-down” periods where temperature may drift, and helps maintain steady-state cooling more easily throughout the journey, thus reducing the risk of quality degradation. Reference
Choosing which ports to call (and in what sequence) affects both transit time and risk. Ports with strong reefer infrastructure (power, inspection, handling) may be prioritised even if slightly off the shortest route. Additionally, planners must consider laytime, gate access, and potential delays. Optimising port calls ensures faster turnaround, better inspection capacity, and minimal risk of quality loss due to port congestion or long waiting times. Reference
Risk-averse routing involves deliberately avoiding high-risk zones (e.g., regions with volatile weather or piracy), even if the route is longer. For reefers, protecting cargo quality often justifies the cost of detours or slower speeds. Optimisation frameworks can assign higher penalties to risk, thereby favouring safer, more predictable paths. This can reduce spoilage, minimise rejection costs, and better guarantee on-time temperature-compliant delivery — especially when the value of cargo is high. Reference
Built for effortless alignment with your container terminal’s IT environment, Reefer Runner quickly becomes part of your operational backbone. No training required; just plug and play with your TOS, install easily and scale as your terminal grows.
Reefer Runner by Identec Solutions
Technology & Equipment: Reefer Container Types | Refrigeration and Airflow Systems | Power Supply and Electrical Systems | Energy Efficiency and Power Optimisation | Sensors, Controls, and IoT Integration | Monitoring and Automation Systems | Maintenance, Lifecycle, and Reliability | Standards, Compliance, and Certification
Transport & Modalities: Overview of Refrigerated Transport | Reefer Vessels and Maritime Operations | Stowage | Intermodal and Inland Reefer Transport | Trade Routes and Global Flows | Cold Corridor and Regional Infrastructure | Reefer Flow Management and Balancing |
Chronology & Operations: Chronology of the Cold Chain | Initial Cargo Conditioning | Pre-Cooling | Staging, Storage, and Cold Integrity | Reefer Handling at Terminals | Empty Reefer and Return Operations | Reefer Maintenance and Technical Inspections |
Monitoring, Data & KPIs: Reefer Monitoring Systems and Infrastructure | Parameters and Data Collection | Alarm Management and Response | Data Management and Analytics | Performance and KPI Measurement |
Cargo & Commodity Handling: Cargo Categories and Industry Applications | Cargo Preparation and Pre-Loading | Packaging and Protection Technologies | Dangerous and Sensitive Goods Handling | Quality Assurance and Traceability |
Sustainability & Environmental Impact: Energy Efficiency and Power Optimisation | Carbon Footprint and Emission Tracking | Packaging and Waste Reduction | Infrastructure Efficiency and Green Design |
Safety: Operational and Equipment Safety | Cargo Handling and Physical Safety | Chemical and Refrigerant Safety | Personnel and Procedural Safety | Training and Continuous Improvement |