How Many Hulls Does a Submarine Have?

Submarines, being unique military and civilian vessels, are equipped with specific hulls designed to function under extreme underwater conditions. This article delves into the number of hulls typically found in submarines and provides detailed insights into their functions and configurations.

The Basics of Submarine Hulls

A submarine typically consists of two main hulls: the pressure hull and the outer hull. These are essential components that ensure the safety and functionality of the vessel during submerged operations.

Pressure Hull

The pressure hull is the innermost structure that is designed to withstand the immense water pressure found in deep underwater environments. It safeguards the crew, equipment, and supplies from the harsh conditions without.

Outer Hull

The outer hull, also known as the light hull or casing, is an additional layer of protection around the pressure hull. This layer not only provides extra structural support but also enhances the submarine's hydrodynamic performance and helps house non-pressure-sensitive systems and equipment.

Modern Submarine Hull Configurations

Modern submarines are usually equipped with two hulls, one inside the other. The inner pressure hull maintains a survivable environment under water, while the outer light hull supports the overall structural integrity and hydrodynamic design. This two-hull configuration is necessary to balance safety and efficient operation.

Older submarines, such as World War II era U-boats, often had a single hull for pressure, complemented by external ballast tanks and a hydrodynamic superstructure. Around 1890, submarines commonly featured all components within a single hull, making them less efficient.

Special Features: Multiple Pressure Hulls

Some specialized submarines, like the Russian Akula class (NATO reporting name Typhoon), contain multiple pressure hulls. These serve various isolated compartments, adding complexity to the overall design and functionality.

The Akula/Typhoon class submarine layout:

Main pressure hull for engineering and crew spaces A separate pressure hull for the control room Another for the torpedo room A small “machinery” compartment pressure hull

Construction and Design Considerations

The dual-hull design in modern submarines helps to minimize the structural weight of the pressure hull while maintaining a streamlined shape, which is crucial for efficient underwater travel. This balance is critical for the overall performance and operational capabilities of the submarine.

Here's a cutaway of the Japanese Soryu class diesel submarine:

The pressure hull is highlighted in pink inside the outer hull.

For older submarines, early designs often had a single hull for pressure, with external ballast tanks, a deck superstructure, and a hydrodynamic prow welded onto the pressure hull. These older designs were not as structurally efficient, leading to greater weight and reduced performance.

Conclusion

Submarines are sophisticated vessels that require careful design and engineering. The typical two-hull configuration is standard, with the inner pressure hull ensuring crew safety and the outer hull providing structural support and hydrodynamic efficiency. Specialized submarines may have additional hulls for specific purposes, adding further complexity to their design and functionality.

submarine hulls, pressure hull, outer hull, dual-hull design, Akula class submarine, Typhoon class submarine, World War II U-boats