Terms & Glossaries of Shipping and Trading

COA (Contract of Affreightment)

An agreement by an ocean carrier to provide cargo space on a vessel at a specified time and for a specified price to accommodate an exporter or importer.

What is COA (Contract of Affreightment) in Shipping?

Contract of Affreightment (COA) is a maritime contract between a shipowner and a charterer, where the shipowner agrees to transport a specified quantity of goods over a specified period using one or more vessels. Unlike a voyage charter or time charter, which involves a single voyage or a set period, a COA covers multiple shipments and voyages over an agreed timeframe.

Key Characteristics of a COA

1. Multiple Voyages:

COA involves multiple voyages rather than a single trip. The contract specifies the total volume of cargo to be transported and the time period within which the shipments will be completed.

2. Flexibility in Scheduling:

Unlike voyage charters, COAs provide flexibility in scheduling shipments. The charterer can spread the cargo movements over the agreed period as per their convenience and requirements.

3. Various Vessels:

The shipowner can use different vessels to fulfill the contract obligations. This flexibility allows for better resource management and optimization of vessel utilization.

4. Quantity of Cargo:

The contract specifies the total quantity of cargo to be transported. This can be detailed in terms of total tonnage or a range of quantities over the contract period.

5. Freight Rates:

Freight rates are agreed upon in advance and can be fixed or variable. Fixed rates provide certainty for budgeting, while variable rates can be adjusted based on market conditions or fuel costs.

6. Loading and Discharging Ports:

The COA specifies the ports of loading and discharging. It can cover a range of ports or specific port pairs depending on the trade routes and cargo requirements.

Advantages of a COA

1. Cost Efficiency:

COAs can offer cost savings compared to individual voyage charters. Bulk contracting for multiple shipments often leads to lower freight rates due to economies of scale.

2. Long-Term Planning:

The long-term nature of a COA allows both parties to plan their operations and logistics more effectively. It provides stability and predictability in cargo movements.

3. Flexibility:

The flexibility in scheduling and vessel usage allows charterers to manage their supply chain more efficiently, accommodating variations in production and demand.

4. Resource Optimization:

Shipowners can optimize their fleet utilization by scheduling multiple voyages under a COA, ensuring better resource allocation and minimizing idle time for vessels.

Disadvantages of a COA

1. Commitment:

Entering into a COA requires a long-term commitment, which can be a risk if market conditions change significantly, affecting freight rates or cargo availability.

2. Complexity:

Managing multiple shipments over a long period can be complex, requiring careful coordination and planning to meet contractual obligations.

3. Potential for Disputes:

Given the long-term nature and multiple shipments involved, there is a higher potential for disputes over scheduling, cargo readiness, and performance standards.

Example Scenario

A mining company produces iron ore and needs to transport it to various buyers across different ports. Instead of negotiating separate contracts for each shipment, the company enters into a COA with a shipping line. The contract specifies the total quantity of iron ore to be shipped over the next year, the loading port in Australia, and various discharging ports in Asia and Europe.

Quantity: 2 million tons of iron ore
Period: One year
Freight Rate: Fixed rate per ton
Vessels: Multiple vessels as per availability

The mining company benefits from the fixed freight rate, ensuring predictable shipping costs, while the shipping line can optimize its fleet utilization by planning the voyages efficiently.


A Contract of Affreightment (COA) is a versatile and strategic maritime contract that benefits both shipowners and charterers by providing flexibility, cost efficiency, and long-term planning capabilities. By covering multiple shipments over an extended period, COAs help streamline logistics and optimize resource usage, making them a valuable tool in the global shipping industry.