Reefer Ships: Types, Temperatures and How They Work
- Dushyant Bisht
- 2 days ago
- 12 min read
Reefer ships transport the bananas in supermarkets, the salmon in restaurants, and the vaccines in hospitals. These refrigerated cargo vessels move over 100 million tonnes of temperature-sensitive goods across the world's oceans each year. For prospective MAT holders evaluating vessel assets on the Shipfinex platform, reefer ships occupy a distinct segment with its own compliance standards, seasonal demand cycles, and technical specifications that directly affect charter earnings.
Quick Answer: What Is a Reefer Ship? A reefer ship is a purpose-built refrigerated cargo vessel designed to transport perishable goods at controlled temperatures. Unlike standard container ships that carry only a limited number of refrigerated containers, dedicated reefer ships have fully insulated cargo holds, built-in refrigeration machinery, and controlled atmosphere systems. They carry fresh fruit, frozen meat, fish, dairy, and pharmaceuticals, with temperatures ranging from +13 degrees Celsius for bananas to -50 degrees Celsius for ultra-frozen bluefin tuna.
Fact | Detail |
Temperature range | +13°C (bananas) to -50°C (bluefin tuna) |
First refrigerated sea voyage | 1876, Argentina to France (Le Frigorifique) |
Primary cargo categories | Fruit, seafood, meat, dairy, pharmaceuticals |
Main vessel types | Conventional, side-door, container reefer, ULT |
Key modern refrigerants | CO2 (R744) and ammonia (NH3) |
Environmental regulations | MARPOL Annex VI, Kigali Amendment, EEXI, CII |
CA notation | Classification society certification for controlled atmosphere holds |
Chartering structures | Time charter (daily rate) and voyage charter (per tonne or lump sum) |
What Is a Reefer Ship?
A reefer ship is a specialized refrigerated cargo vessel built to maintain precise temperature and humidity conditions throughout an ocean voyage. The term reefer is shorthand for refrigerated. These vessels are built specifically for cold chain transport, with insulated cargo holds, integrated cooling machinery, and atmosphere management systems. They differ from standard container ships, which carry a limited number of refrigerated containers as part of a general cargo mix.
The refrigerated cargo shipping industry traces its origin to 1876, when the steam vessel Le Frigorifique completed the first successful chilled meat voyage from Argentina to France using compressed air cooling. Mechanical refrigeration replaced ice and air systems through the 20th century. The containerization era of the 1970s and 1980s brought refrigerated ISO containers, but purpose-built reefer ships remain commercially essential for high-volume, ultra-temperature-sensitive, and pharmaceutical cargo where container performance falls short.
What Are the Main Types of Reefer Ships?
Reefer ships fall into five primary categories. Conventional reefer ships carry insulated tween decks, intermediate cargo floors that divide the hold into layers, and handle bulk fruit and frozen meat with capacity from 100,000 to 500,000 cubic feet. Side-door reefer ships load palletized cargo through ports in the ship's side rather than top hatches, cutting port turnaround time significantly for high-value fruit trades.
Container reefer ships are purpose-built to carry refrigerated ISO containers connected to the ship's power supply. Ultra-low-temperature vessels are designed for deep-freeze cargo such as bluefin tuna and maintain temperatures at or below -50 degrees Celsius. Fish carrier and processing vessels combine onboard fish processing decks with reefer storage and typically operate in remote Pacific fishing grounds.
Vessel Type | Hold Design | Temp Range | Best Cargo | Key Trade Routes |
Conventional Reefer | Insulated tween decks | -25°C to +13°C | Fruit, meat, fish | S. America to Europe |
Side-Door Reefer | Side-loading ports | -25°C to +13°C | Palletised fruit | Caribbean, W. Africa |
Container Reefer | ISO RF plug-in units | -25°C to +2°C | Mixed perishables | Global liner routes |
ULT Reefer | Deep-freeze holds | -50°C | Bluefin tuna | Pacific, Indian Ocean |
Fish Tender/Processor | Processing decks + reefer | -30°C to -50°C | Fresh catch, fillets | Pacific fishing grounds |
How Do Reefer Ships Keep Cargo Cold?
Modern reefer ships use forced-air circulation as the primary cooling method. Cold air generated by compressors moves through ducts and evaporators, then returns through grate floors beneath the cargo. This ensures consistent temperature across large hold volumes. For fruit cargo specifically, airflow matters most because hot spots trigger premature ripening.
Older conventional reefer ships relied on brine cooling, circulating a chilled saltwater-glycol solution through pipes embedded in the cargo hold walls and floors. Newbuild vessels have largely moved on from this. The larger shift across the modern reefer fleet is the transition from HFC refrigerants (R134a, R404A) to natural refrigerants including CO2 (R744) and ammonia (NH3). Both carry zero ozone depletion potential and very low global warming potential, making them the preferred specification under current F-gas and MARPOL regulations.
All commercial reefer ships carry onboard temperature logging systems that record data continuously and trigger alarms on excursions. Modern vessels use IoT-connected monitoring that allows cargo owners and insurance underwriters to track conditions in real time. Temperature log documentation forms critical evidence in cargo insurance claims following any excursion event.
What Temperatures Do Reefer Ships Maintain?
Different cargo types require specific temperature and humidity bands during transport. Shipping outside these ranges triggers insurance claims, cargo rejection at destination, and regulatory reporting requirements.
Category | Examplek | Temperature Range | Humidity Range | Notes |
Tropical Fruit | Bananas | +13°C to +14°C | 90 to 95% | Ethylene-sensitive |
Citrus | Oranges | +5°C to +8°C | 85 to 90% | CA beneficial |
Chilled Protein | Fresh beef | -1.5°C to +1°C | 85 to 95% | High air circulation |
Frozen Seafood | Tuna (ULT) | -50°C | Low | ULT vessel required |
Frozen Meat | Beef, lamb | -18°C to -25°C | Low | Standard frozen |
Dairy | Butter | +2°C to +5°C | 80 to 85% | Odour segregation |
Pharmaceuticals | Vaccines | +2°C to +8°C | Controlled | GDP compliance |
Ethylene is a natural ripening hormone that fruit emits during storage. Ethylene-sensitive produce such as bananas must be segregated from high-ethylene-producing fruits. Reefer ships equipped with controlled atmosphere technology use ethylene scrubbers to remove this gas from hold air, preventing uncontrolled ripening on long voyages.
Reefer Ship vs Reefer Container: Which Should You Use?
A reefer container is a standalone ISO-standard refrigerated box, available in 20-foot and 40-foot sizes, with its own self-contained compressor unit that plugs into a power outlet on a standard container ship. Reefer containers are widely accessible at ports through global liner networks, but their individual compressor units offer less precise temperature control than a dedicated reefer ship's hold system.
Factor | Dedicated Reefer Ship | Reefer Container on Container Ship |
Temperature control precision | Higher (centralised system) | Moderate (individual unit) |
Cargo volume flexibility | Large bulk volumes | Small to medium shipments |
Port accessibility | Requires specialist reefer ports | Any container port |
Cost per unit | Lower for full cargo loads | Higher for small volumes |
Pharmaceutical suitability | Specialist vessels only | GDP-certified boxes available |
ULT cargo (-50°C) | Yes (ULT vessels) | Not available in ISO containers |
Dedicated reefer ships suit large-volume exporters on fixed trade lanes, including banana and citrus producers, frozen meat exporters, and ULT tuna trades. Reefer containers fit small to mid-volume shippers, mixed cargo consignments, and routes where dedicated reefer vessel schedules do not match shipping needs. Pharmaceutical shippers handling high-value biologics above +8 degrees Celsius typically prefer specialist reefer vessels over standard GDP-certified containers.
What Is Controlled Atmosphere (CA) Technology?
Controlled atmosphere storage manages oxygen, carbon dioxide, and nitrogen levels inside a cargo hold in addition to temperature and humidity. Lowering oxygen and elevating CO2 slows the respiration rate of fresh produce, extending shelf life well beyond what refrigeration alone can achieve. Bananas shipped under CA conditions can remain green for weeks longer than under standard refrigeration, which opens distant markets that would otherwise be unreachable.
CA systems on reefer ships use nitrogen generators, CO2 scrubbers, and ethylene scrubbers. Nitrogen generators produce inert gas to displace oxygen in the hold. CO2 scrubbers maintain carbon dioxide at the target level for each cargo type. Ethylene scrubbers remove the ripening hormone from the air, preventing premature ripening of ethylene-sensitive produce. Real-time gas monitoring systems continuously track O2, CO2, and ethylene levels across the voyage.
Vessels certified for CA operations carry a CA notation from classification societies such as Bureau Veritas, Lloyd's Register, and DNV. Charterers evaluating ships for high-value produce trades verify CA notation status alongside temperature range capability and hold capacity.
What Environmental Regulations Apply to Reefer Ships?
Reefer ships face two primary regulatory pressures: refrigerant compliance and energy efficiency. The Kigali Amendment to the Montreal Protocol mandates the global phasedown of HFC refrigerants, affecting vessels operating R134a and R404A systems. Fleet operators must plan refrigerant transition programmes across maintenance cycles as HFC supply restrictions tighten. New vessels now specify natural refrigerant systems (CO2 and ammonia) as the long-term compliant baseline.
MARPOL Annex VI governs energy efficiency. The Energy Efficiency Existing Ship Index (EEXI) became mandatory in January 2023 and sets a carbon intensity baseline for operating vessels. The Carbon Intensity Indicator (CII) assigns each vessel an annual A to E rating based on actual CO2 emissions per cargo capacity per nautical mile. A reefer ship receiving a D rating for two consecutive years or an E rating for one year must submit a corrective action plan. Poor CII ratings restrict charter options with major cargo owners who now include CII performance clauses in freight contracts.
Cold ironing connects a vessel to shore-side electrical power while in port, allowing refrigeration systems to operate without running main generators. This reduces emissions and fuel consumption at berth. Major reefer ports in Europe and Asia have invested in shore power infrastructure as part of port decarbonization programmes, and cold ironing capability is becoming a meaningful factor in vessel evaluation.
What Are the Major Reefer Trade Routes?
Origin Region | Destination | Primary Cargo | Vessel Type | Transit (approx.) |
Chile / Ecuador | Rotterdam, Hamburg, Antwerp | Bananas, grapes, blueberries | Conventional / Side-door | 20-25 days |
New Zealand / Australia | China, Japan, Gulf states | Lamb, beef, dairy | Conventional reefer | 18-25 days |
Pacific fishing zones | Japan (via transshipment) | Bluefin tuna | ULT reefer | Varies |
Global pharma hubs | Developing markets | Vaccines, biologics | Specialist reefer | Route-dependent |
South America to Europe is the dominant conventional reefer trade lane. Chile and Ecuador ship bananas, grapes, and blueberries to Rotterdam, Hamburg, and Antwerp on voyages of 20 to 25 days from the South Atlantic. Southern Hemisphere harvest seasons from November to April drive vessel demand peaks and create predictable seasonal freight rate cycles.
Pacific tuna trade routes cover bluefin fishing zones across the Pacific Ocean and rely on transshipment at intermediate ports including Manta, Ecuador, Tema, Ghana, and Bangkok. ULT vessels carry premium cargo to Japan, where bluefin pricing supports the specialist -50 degree Celsius cold chain economics.
How Do You Charter or Buy a Reefer Ship?
Eight factors govern reefer vessel evaluation for charter or purchase. Working through this checklist before commercial engagement prevents the most common first-shipment problems.
1. Cargo hold cubic capacity (cubic feet or cubic metres) versus your required volume.
2. Refrigerant type and F-gas compliance status. HFC systems face supply restrictions; CO2 and ammonia systems are long-term compliant.
3. CA notation. Verify CA classification if your cargo requires controlled atmosphere storage.
4. Temperature range capability versus your cargo specification (standard, frozen, or ULT).
5. Vessel age and classification survey status. Survey timing affects dry-dock scheduling and off-hire risk.
6. Port compatibility with your loading and discharge ports. Conventional reefers require specialist reefer terminals.
7. Flag state and P&I Club coverage. Verify protection and indemnity insurance arrangements.
8. EEXI and CII rating trajectory. A declining CII rating restricts charterability with major cargo owners.
Time charter arrangements hire the vessel for a set period at a daily rate, shifting voyage cost risk to the charterer. Voyage charter agreements hire the vessel for a specific cargo movement at a rate per tonne or a lump-sum freight amount. Reefer freight rates fluctuate based on seasonal harvest windows, bunker fuel prices, and fleet utilisation. Most reefer charter transactions move through specialist brokers including Clarksons and BRS Group.
Why Reefer Ships Matter to Prospective MAT Holders
Reefer ships sit in a structurally distinct part of global maritime trade. Cargo demand runs on physical fundamentals: food production in Southern Hemisphere regions and consumption in Northern Hemisphere markets create predictable seasonal freight rate cycles that contrast with the higher volatility of tanker and dry bulk segments. The pharmaceutical cold chain adds a high-growth, high-value cargo stream where strict GDP compliance requirements support premium freight rates.
For prospective MAT holders evaluating vessels listed on the Shipfinex platform under VARA In-Principle Approval, technical due diligence data on reefer assets includes classification survey status, refrigerant compliance, CII ratings, and CA notation. These factors influence charter eligibility with major produce and pharmaceutical cargo owners and directly affect the SPV's revenue. Understanding reefer-specific compliance requirements is essential to interpreting charter performance data.
The HFC-to-natural-refrigerant transition and tightening MARPOL energy efficiency requirements are the two structural shifts reshaping reefer fleet economics this decade. Vessels with compliant refrigerant systems and strong CII ratings can access premium charter markets; non-compliant vessels face restricted employment. Asset evaluation that accounts for these factors avoids mid-cycle surprises from mandatory system upgrades.
What to Remember
• Reefer ships are purpose-built refrigerated cargo vessels with insulated holds and integrated cooling machinery, carrying cargo at temperatures from +13°C for bananas to -50°C for ultra-frozen bluefin tuna.
• Controlled atmosphere technology manages oxygen, CO2, and nitrogen levels alongside temperature, extending produce shelf life and justifying premium freight rates for CA-equipped ships.
• The global HFC refrigerant phasedown under the Kigali Amendment is forcing operators to replace R134a and R404A systems with natural refrigerants including CO2 (R744) and ammonia (NH3).
• MARPOL Annex VI EEXI and CII ratings directly affect charterability with major cargo owners, making energy efficiency compliance a commercial factor in every charter negotiation from 2023 onward.
• Seasonal freight rate cycles on major reefer trade lanes create predictable demand patterns that prospective MAT holders should evaluate before acquiring economic exposure to a reefer asset.
Frequently Asked Questions
What is a reefer ship?
A reefer ship is a purpose-built refrigerated cargo vessel with insulated holds and built-in cooling systems, designed to transport perishable goods including fruit, meat, fish, dairy, and pharmaceuticals at controlled temperatures between +13°C and -50°C.
What is the difference between a reefer ship and a reefer container?
A reefer ship is a dedicated refrigerated vessel with cooling systems integrated into the hold. A reefer container is an independent refrigerated ISO box with its own compressor that plugs into a power source on a standard container ship. Reefer ships maintain more precise temperature control across large volumes. Reefer containers offer wider port access for smaller shipments.
What temperatures do reefer ships maintain?
Temperature varies by cargo. Bananas travel at +13°C to +14°C, chilled meat at -1.5°C to +1°C, frozen fish at -18°C to -25°C, pharmaceuticals at +2°C to +8°C for GDP compliance, and bluefin tuna in ULT vessels at -50°C.
What is Controlled Atmosphere (CA) technology?
CA technology manages oxygen, CO2, and nitrogen levels in the cargo hold alongside temperature and humidity. Lowering oxygen and raising CO2 slows fruit respiration and extends shelf life. Ethylene scrubbers remove the ripening hormone from hold air to further delay produce maturation on long voyages.
What environmental regulations apply to reefer ships?
Reefer ships are governed by MARPOL Annex VI (air pollution and energy efficiency), the Kigali Amendment (HFC phasedown), and IMO EEXI and CII requirements effective January 2023. Poor CII ratings restrict chartering options with major cargo owners who include performance clauses in freight contracts.
What refrigerants do modern reefer ships use?
Older vessels use HFC refrigerants such as R134a and R404A. Newbuilds and modern vessels are transitioning to natural refrigerants including CO2 (R744) and ammonia (NH3), which carry zero ozone depletion potential and meet current and future F-gas regulations under the Kigali Amendment.
How do I charter a reefer ship?
Reefer vessels are chartered through specialist maritime brokers such as Clarksons and BRS Group, either on time charter (daily rate over a fixed period) or voyage charter (per tonne or lump sum for a specific cargo movement). Key evaluation factors include cubic capacity, temperature range, CA notation, refrigerant compliance, vessel age, and CII rating.
What is a CA notation on a reefer ship?
A CA notation is a classification society certification confirming a vessel's cargo holds are equipped and certified for Controlled Atmosphere storage operations. Bureau Veritas, Lloyd's Register, and DNV issue these notations, which charterers verify when evaluating vessels for high-value produce trades requiring extended shelf life.
Glossary of Reefer Shipping Terms
Reefer Ship: A purpose-built refrigerated cargo vessel with insulated holds and integrated cooling machinery for transporting temperature-sensitive cargo.
CA (Controlled Atmosphere): Cargo preservation technology managing oxygen, CO2, and nitrogen levels in a hold to extend the shelf life of fresh produce.
ULT (Ultra-Low Temperature): Deep-freeze refrigeration classification for vessels maintaining temperatures at or below -50°C, used primarily for bluefin tuna.
Tween Deck: Intermediate deck inside a ship's cargo hold dividing it into layers, used in conventional reefer ships for pallet stacking and airflow management.
CA Notation: Classification society certification confirming a ship's cargo holds are equipped and certified for Controlled Atmosphere storage operations.
HFC Refrigerant: Hydrofluorocarbon-based refrigerants (R134a, R404A) historically used in reefer systems; being phased down under the Kigali Amendment.
CO2 (R744): Carbon dioxide used as a natural refrigerant in modern marine cooling systems; zero ozone depletion potential and very low global warming potential.
Ammonia (NH3): Natural refrigerant used in industrial marine cooling systems; highly energy-efficient with zero global warming potential.
Ethylene Scrubber: A system on CA-equipped reefer ships that removes ethylene gas from cargo hold air, preventing premature ripening of ethylene-sensitive produce.
MARPOL Annex VI: The annex of the International Convention for the Prevention of Pollution from Ships covering air pollution and vessel energy efficiency.
EEXI: Energy Efficiency Existing Ship Index; an IMO-mandated efficiency rating setting a carbon intensity baseline for ships in operation from January 2023.
CII: Carbon Intensity Indicator; an annual A to E IMO rating measuring a ship's actual CO2 emissions per cargo-carrying capacity per nautical mile.
Kigali Amendment: A 2016 amendment to the Montreal Protocol requiring the global phasedown of HFC refrigerants.
Cold Ironing: Connecting a ship to shore-side electrical power while in port, allowing refrigeration systems to run without the ship's main generators.
Time Charter: A chartering arrangement where the shipowner leases a ship to a charterer for a specified period at an agreed daily hire rate.
Voyage Charter: A chartering arrangement where a ship is hired for a specific cargo movement at a rate per tonne or a lump-sum freight amount.
GDP (Good Distribution Practice): WHO and EU-regulated standards governing the handling, storage, and transport of temperature-sensitive pharmaceutical products.
Temperature Excursion: An event where cargo temperature rises or falls outside the specified range during transport, potentially triggering insurance claims and regulatory reporting.
Brine Cooling System: A legacy refrigeration method using chilled saltwater-glycol solution circulated through pipes in cargo hold walls and floors; largely replaced on newbuilds.
Citations
Risk Disclosure: This content is produced for informational and educational purposes only. It does not constitute financial advice, investment advice, or a solicitation to acquire any financial product. Participation in maritime asset ownership through the Shipfinex platform carries financial risk, including the potential for values to decline materially below purchase price. Shipfinex operates under VARA In-Principle Approval (IPA/26/01/002) and Poland VASP registration. All prospective MAT holders should conduct independent due diligence and seek professional financial and legal advice before any commitment. Past performance of maritime assets does not indicate future outcomes.
Dushyant Bisht
Expert in Maritime Industry
Dushyant Bisht is a seasoned expert in the maritime industry, marketing and business with over a decade of hands-on experience. With a deep understanding of maritime operations and marketing strategies, Dushyant has a proven track record of navigating complex business landscapes and driving growth in the maritime sector.
Email: [email protected]