Do Cargo Ships Refuel at Sea?

Cargo ships primarily refuel in ports or at anchorages near ports rather than at sea. This practice is based on several factors including safety, convenience, and operational efficiency.

Refueling at Ports

Cargo ships obtain fuel from either shore-based facilities or from bunker ships. Bunker ships are specialized vessels that supply fuel directly to the cargo ship while it is docked or anchored. The ship loads enough fuel to complete its current voyage, along with additional reserves to cover unexpected emergencies or delays.

Special Circumstances

In certain trades, such as the delivery of heavy fuel oil (HFO) from ships like Very Large Crude Carriers (VLCCs) operating in the U.S. West Coast or the Gulf of Mexico, lightering vessels may bring HFO for the return voyage if needed. Alternatively, HFO might be cheaper when delivered to the lightering area. However, this is not a common practice across the industry.

Refueling at Sea - A Rare Occurrence

Generally, cargo ships do not refuel at sea due to various challenges. Refueling a ship at sea is both complex and risky. The only instances when ships might refuel at sea are when they are patrolling and cannot afford to return to port for refueling, such as in cases involving naval operations.

Perspectives From Seamen

According to experienced seamen, it can be feasible to refuel at sea depending on the situation. For instance, in cases where office advice suggests meeting a bunker barge at sea or at the nearest island capable of supplying fuel, it can be done. However, this would typically be a rare and specific event.

The Practicality of Refueling in Ports

The vast majority of cargo ships are designed to carry enough fuel to last for extended periods, usually anywhere from 40 to 50 days of continuous steaming. Therefore, there is no necessity to refuel at sea for regular operations. Major ports often offer cost-effective fuel sources compared to other locations, making port refueling the preferred and more practical choice.

References to Specific Cases

Some notable exceptions are the Titanic and sailing vessels without an engine, which would require refueling or resupply. For cargo ships, the need for extensive refueling is managed by requesting the required amount of fuel well in advance before the bunkering port. The fuel can be supplied by barges, trucks, or directly from shore tanks, depending on the port facilities.

For more detailed information on cargo ship operations and fuel management, refer to the MarineTraffic website.