The Longest World War II Submarine Patrols without Port Resupply

During World War II, submarines played a crucial role in naval warfare, patrolling the vast expanses of the world’s oceans and disrupting enemy supply lines. One remarkable aspect of submarine operations was their ability to remain at sea for extended periods without replenishment. In this article, we delve into the historical record to uncover the longest patrols conducted by World War II submarines without the need for port resupply.

The Gato-class submarines

The Gato-class submarines used by the United States Navy were renowned for their endurance and long-range capabilities. Equipped with advanced technology and designed for extended deployments, these submarines formed the backbone of the American submarine fleet during World War II.

USS Tang (SS-306)

The USS Tang holds the distinction of conducting one of the longest unsupported patrols during World War II. Under the command of Lieutenant Commander Richard H. O’Kane, the Tang embarked on an epic journey through the Pacific Theater. On its fifth and final patrol, the Tang spent an astonishing 75 days at sea, from October 23, 1944 to January 5, 1945, without returning to port for replenishment.

Operational Challenges and Adjustments

Extended patrols presented numerous challenges to submarine crews. Conservation of supplies, including fuel, food, water, and ammunition, was critical. Crew members had to adapt and ration resources to sustain themselves and the submarine during these long deployments. The crew’s resilience, discipline, and resourcefulness were essential to the success of the extended patrols.

Innovations in Technology

The success of extended submarine patrols was also facilitated by technological advances. Improved diesel engines, increased fuel storage capacity, and improved torpedoes allowed submarines to operate for longer periods of time without the need for replenishment. These innovations provided greater range and lethality, allowing submarines to remain submerged and undetected for extended periods of time.

Strategic Considerations

Extended patrols without replenishment were often part of strategic naval operations. Submarines were used to scout enemy positions, disrupt enemy supply lines, gather intelligence, and conduct offensive operations. The ability to remain at sea for extended periods allowed submarines to maintain a persistent presence in key areas, maximizing their impact on the war effort.

Other Notable Patrols

While the USS Tang’s 75-day patrol stands as one of the longest recorded during World War II, other submarines also achieved remarkable durations at sea without replenishment. Submarines such as the USS Barb, USS Flasher, and USS Parche conducted patrols of 60 days or more, demonstrating the remarkable capabilities of these ships and their crews.

Submarine Classes and Types

In addition to the Gato-class submarines, other submarine classes and types from various nations conducted extensive patrols during World War II. German submarines, such as the Type IX and Type VII, were known for their endurance and long-range capabilities. British submarines, including the T-Class and S-Class, also contributed to the war effort with extended patrols.

Crew endurance and living conditions

Extended patrols placed a significant physical and psychological strain on submarine crews. Submarine living conditions were cramped, and crew members had to adapt to the confined spaces for extended periods of time. Lack of privacy, limited fresh air, and constant operational stress added to the crew’s challenges. Maintaining morale and psychological well-being was critical to the success of extended patrols.

Supply Management

Efficient supply management was critical to sustaining extended patrols. Submarines carried limited supplies, including food, water, fuel, and ammunition. Crew members carefully rationed supplies to ensure they would last for the duration of the patrol. Some submarines used innovative techniques, such as water distillation systems and hydroponic gardens, to produce fresh water and grow limited amounts of fresh produce.

Refueling and resupplying at sea

While submarines aimed to avoid port resupply during extended patrols, they sometimes received essential items such as mail, spare parts, or medical supplies by rendezvousing with support ships or other submarines at sea. These resupply operations were challenging and required precise coordination to safely transfer supplies between moving vessels.

Impact on the War Effort

Extended submarine patrols had a significant impact on the war effort. They disrupted enemy shipping, sank merchant vessels, and targeted enemy naval installations. By cutting off vital supply routes and damaging enemy morale, submarines played a crucial role in undermining the enemy’s ability to sustain its war machine.

Technological Advances

Throughout the war, submarines benefited from technological advances that enhanced their capabilities. These included improved sonar systems, radar detection, and torpedo guidance systems. These innovations enhanced the submarines’ ability to detect and attack enemy targets, increasing their effectiveness during extended patrols.

Post-War Developments

The experience and lessons learned from World War II submarine operations paved the way for further advances in submarine technology and tactics. Post-war developments led to the introduction of nuclear-powered submarines, improved battery technologies, and more efficient air and water recycling systems, further extending submarine endurance and range.


The ability of World War II submarines to remain at sea for extended periods without replenishment was a testament to their endurance, technological advances, and the resilience of their crews. The USS Tang’s 75-day patrol represents a remarkable achievement in submarine operations and underscores the strategic value of extended deployments. These accomplishments underscore the critical role submarines played in disrupting enemy naval operations and contributing to the overall success of the Allied forces during World War II.


What was the longest a World War II submarine stayed at sea without being resupplied at a port?

The USS Tang (SS-306) holds the record for the longest World War II submarine patrol without port replenishment, remaining at sea for 75 days from October 23, 1944 to January 5, 1945.

How long could a ww2 submarine stay out at sea?

Two 126-cell battery groups gave her a submerged top speed of 8.75 knots (16.2 km/hr); holding her speed to 2 knots (4 km/hr), she could remain submerged for 48 hours.

How long did German U-boats stay at sea?

Due to fresh food becoming spoilt from exposure to diesel fumes and being stored in a damp environment, the crew could only store canned goods. The long war cruises – which could last up to six months – took a large psychological toll on many of the crew members.

How many U-boats have not been found?

Despite their prevalence during World War I and World War II, only four U-boats remain intact today.

How long is a ww2 submarine?

They had a length of about 225 feet, beam of 20 feet, and draft of 15 feet. They were of single hull construction, with surface displacement of about 850 tons, and submerged displacement of 1100 tons. They had four or five 21″ torpedo tubes in the bow, and could carry 12 Mk. 10 steam torpedoes.

What is the longest a submarine has stayed submerged?

111 days

The longest submerged and unsupported patrol made public is 111 days (57,085 km 30,804 nautical miles) by HM Submarine Warspite (Cdr J. G. F. Cooke RN) in the South Atlantic from 25 November 1982 to 15 March 1983.

How long can a Russian submarine stay underwater?

The United States, Russia, China, Britain, and France all have fleets of submarines that carry nuclear missiles. The most advanced of these subs are nearly undetectable and can stay submerged for months. A U.S. Trident nuclear submarine carries 24 missiles, each fitted with several independently targeted warheads.

What was the last U-boat sunk in ww2?


U-853 was one of the last U-boats sunk during World War II and the last to be sunk in US waters. (U-881 was sunk the same day in the North Atlantic.) Atherton and Moberly received joint credit for the kill.

How close did the German U-boats get to Canada?

“The closest they got to what you could call the Canadian heartland is within 172 miles of Quebec City in the St. Lawrence River,” he said. The farthest-inland U-Boat, thus, would have come roughly within sight of Baie-Comeau just as a young Brian Mulroney was taking his first steps.

How deep could a ww2 U-boat dive?

German submarine U-352

Nazi Germany
Range 8,500 nmi (15,700 km; 9,800 mi) at 10 knots (19 km/h; 12 mph) surfaced 80 nmi (150 km; 92 mi) at 4 knots (7.4 km/h; 4.6 mph) submerged
Test depth 230 m (750 ft) Crush depth: 250–295 m (820–968 ft)
Complement 4 officers, 40–56 enlisted

How long can a submarine stay out at sea?

three months

Submarines generally stock a 90-day supply of food, so they can spend three months underwater. The diesel-powered submarines (not now used by the United States Navy) had a limit of several days submerged.

How long do submarines stay out?

The Submarine Force is often called “The Silent Service” because of how it operates. Submarines can submerge more than 600 feet below the ocean’s surface for up to four months at a time, constantly patrolling and working classified missions.

How far could a ww2 submarine go?

On the surface, powered by four diesel engines, the Balao had a top speed just over 20 knots (37 km/hr); cruising at 10 knots (18 km/hr) her range was 11,000 nautical miles (20,000 km).

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