The British submarine HMS Thetis, built in the late 1930s, was intended to be a state-of-the-art vessel that showcased British naval engineering prowess. However, tragedy struck during its maiden voyage on June 1, 1939, when the submarine sank with the loss of 99 crew members.

Here we will explore the construction of HMS Thetis, its crew and armaments, its service record, the circumstances surrounding its sinking, and the lasting impact of this devastating event.

Construction and Armaments

The construction of HMS Thetis began in 1936 at the Cammell Laird shipyard in Birkenhead, England. It was the first of the T-class submarines built for the Royal Navy. The Thetis was designed to be a cutting-edge vessel, measuring approximately 275 feet in length and with a displacement of around 1,500 tons.

Equipped with eight torpedo tubes, the Thetis had the capacity to launch torpedoes for offensive purposes. It also carried six external tubes for releasing mines.

The submarine was armed with a variety of torpedoes, including the Mark VIII and Mark IX, which had a range of approximately 4,500 yards and 11,000 yards, respectively.

The Cammell Laird Shipyard

The Cammell Laird shipyard in Birkenhead, located in Merseyside, England, played a significant role in the construction of HMS Thetis. The shipyard has a rich history in shipbuilding and engineering, dating back to its establishment in 1824. It has been involved in the construction of various naval vessels, including submarines, during its long-standing operation.

Cammell Laird was chosen as the construction site for HMS Thetis due to its expertise and reputation in building submarines. The shipyard had previously worked on the construction of other submarines for the Royal Navy, and its capabilities made it a suitable choice for such a technologically advanced vessel.

Cammell Laird’s covered submarine building pens seen in 2006. Thetis was built at this yard.

The skilled workforce at Cammell Laird meticulously assembled the various components of the submarine. They ensured that the highest standards of quality and craftsmanship were met.

The shipyard’s facilities provided the necessary infrastructure and resources to undertake the complex construction process, which involved integrating the submarine’s hull, propulsion systems, armaments, and other critical components.

Throughout the construction period, engineers and workers at Cammell Laird worked diligently to bring HMS Thetis to completion. The shipyard’s reputation for delivering reliable and seaworthy vessels instilled confidence in the Royal Navy and the submarine’s eventual crew.

However, the tragedy of the sinking of HMS Thetis during its sea trials off the coast of Liverpool Bay overshadowed the shipyard’s efforts. The sinking not only resulted in the loss of valuable lives but also raised questions about the design and construction of the submarine.

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Despite the unfortunate outcome, the Cammell Laird shipyard continued to contribute to the construction of numerous naval vessels. They continued with submarines, and other maritime projects.

Crew and Service Record

The crew of HMS Thetis consisted of 103 personnel, including officers, engineers, and ratings. They were highly trained individuals responsible for operating and maintaining the submarine’s complex systems.

The crew comprised a mix of experienced naval officers and skilled enlisted personnel. The officers held various ranks, including the commanding officer, executive officer, navigation officer, engineering officer, and weapons officer. These officers oversaw the different aspects of submarine operations, ensuring the efficient functioning of the vessel.

Submarine crews have always had to be well trained and have discipline. Its a tough job and a dangerous one.

The engineering team played a vital role in operating and maintaining the submarine’s propulsion systems, electrical systems, and other mechanical components. They were responsible for monitoring the performance of the machinery and ensuring its proper functioning.

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The ratings, consisting of petty officers and sailors, performed various duties on board the Thetis. These included serving as sonar operators, torpedomen, communications specialists, and other essential roles necessary for the submarine’s operations.

The crew of HMS Thetis underwent extensive training to develop the necessary skills and knowledge required to operate a submarine. This training included submarine familiarisation, technical training, emergency procedures, and teamwork exercises. The crew members were expected to work together seamlessly, especially during critical situations such as diving, surfacing, and combat scenarios.

The submarine was commissioned in March 1939 and was assigned to the 2nd Submarine Flotilla based in Portsmouth, England.

Sinking of HMS Thetis

On June 1, 1939, during its maiden voyage, HMS Thetis encountered a series of critical failures that led to its sinking off the coast of Liverpool Bay. The exact sequence of events that caused the sinking can be attributed to a combination of design flaws, human errors, and technical malfunctions.

As the submarine prepared to submerge, the crew closed the outer torpedo tube doors. However, due to a design flaw, four of the doors failed to close properly. This allowed seawater to enter the torpedo tubes, causing the submarine’s bow to become negatively buoyant.

A Fatal Mistake

Despite the flooding, the crew proceeded with the dive. As the Thetis submerged, the flooding increased, and seawater continued to fill the forward compartments of the vessel. The crew attempted to pump out the water using the onboard pumps, but they were overwhelmed by the rate of flooding.

Rescue boats try in vain to help the crew of the stricken submarine.

The flooding had a cascading effect on the submarine’s stability. As the bow sank lower, the stern rose higher, causing the propellers to emerge from the water. This resulted in the loss of propulsion and manoeuvrability, further exacerbating the dire situation.

Too Little too Late

With the submarine rapidly descending, the crew attempted to activate the emergency buoyancy tanks to bring the Thetis back to the surface. However, due to a combination of design flaws and human error, the tanks were not fully flooded, rendering them ineffective.

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As the Thetis sank to the seabed, the crew faced the daunting challenge of escape. The submarine’s main escape hatch, located in the forward section, proved to be extremely difficult to open. It required a high level of physical strength and coordination, which was hindered by panic and the lack of clear instructions.

Ultimately, only four crew members managed to escape through the narrow emergency escape chamber, while the remaining 99 crew members were trapped inside the sinking submarine and lost their lives.

Aftermath and Legacy

The sinking of HMS Thetis had a profound impact on submarine safety and the Royal Navy. The loss of life and the circumstances surrounding the disaster prompted extensive investigations and led to significant changes in submarine design, training, and operational procedures.

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The investigation into the sinking of HMS Thetis revealed several design flaws and human errors that contributed to the tragedy. One major flaw was the inadequacy of the main escape hatch. Its design made it extremely difficult to open, especially when the submarine was submerged. This flaw prevented many crew members from reaching safety.

HMS Thetis sinks helplessly despite the efforts of Royal Navy crew. Lessons were to be learnt.

Another contributing factor was the lack of communication and coordination between the crew members. The confusion and panic that ensued hindered the successful evacuation of the submarine. Additionally, insufficient training and familiarity with the submarine’s systems and emergency procedures further exacerbated the situation.

In the aftermath of the Thetis sinking, the Royal Navy took immediate action to improve submarine safety. Design modifications were implemented to enhance the accessibility and reliability of escape hatches. Furthermore, emergency systems, such as flooding detection and emergency buoyancy control, were upgraded to prevent similar incidents in the future.

Lessons Learnt

Crew training and drills were intensified to ensure that all personnel were well-versed in emergency procedures and capable of responding effectively in crisis situations. Lessons learned from the Thetis sinking became integral in shaping the training curriculum for submarine crews, emphasising the importance of clear communication, calm decision-making, and teamwork.

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The tragedy also underscored the need for improved rescue capabilities. The Royal Navy developed and implemented more advanced submarine rescue vessels and equipment. These advancements aimed to provide faster response times and increased chances of rescuing submariners in distress.

The memorial to the crew of the Thetis in Woodside, Birkenhead, UK.

The sinking of HMS Thetis also had a lasting impact on the public’s perception of submarine safety. The incident garnered significant media attention, highlighting the risks associated with submarine operations and the sacrifices made by submariners. The loss of so many lives served as a poignant reminder of the dangers inherent in naval service.

In conclusion, the sinking of HMS Thetis was a tragic event that led to the loss of 99 crew members and highlighted critical deficiencies in submarine safety.

The investigation into the incident prompted substantial changes in submarine design, training, and rescue procedures. The legacy of the Thetis disaster serves as a reminder of the ongoing pursuit of safety in submarine operations and the commitment to protecting the lives of submariners.