Can a Submarine Periscope Help in Underwater Navigation and Surveillance?

The question often arises whether a submarine can effectively make use of its periscope while submerged. The answer is nuanced and depends on specific circumstances. A submarine periscope, with its historical and technological evolution, does offer some useful functionalities, particularly in certain scenarios. This article delves into the capabilities and limitations of using a submarine periscope underwater, its historical significance, and how it fits into modern naval operations.

The Historical Context and Evolution of the Submarine Periscope

Sailing beneath the waves, a submarine must navigate with precision and stealth. One of the most crucial tools for submarine officers was, and in some cases still is, the periscope. Originating in the early 20th century, the periscope evolved to become a vital component of naval warfare, allowing submarines to observe their surroundings without surfacing. The first submarine periscope, developed in the late 19th century, was an optic tube extending above the waterline. However, as technology advanced, so did the design and functionality of the periscope.

Using a Periscope in Deep Submerged Conditions

Though periscopes were primarily designed for and most effective when a submarine was at or near the periscope depth (about 10 to 15 meters or 33 to 49 feet above the waterline), there have been instances where they provided useful data even when the submarine was fully submerged or only partially above water.

Disturbed Water and Surface Observations

At times, the periscope would only allow the officer of the deck to see the disturbed water above the surface. This would often be mere ripples or disturbances. Yet, in certain situations, the periscope could be used to observe the undersides of waves, which might reveal the presence of ships or other objects.

Enhanced Visibility and Surveillance

However, the most useful capability of the periscope comes into play when a submarine is surfacing or is near periscope depth. At these times, the officer can use the periscope to observe the hull of a ship that is dead in the water on the surface. Surfaces ships, especially those that are quiet and not moving rapidly, create distinct shapes and identifiable features in the water, which the periscope can make visible.

Hidden Reconnaissance

Another unique advantage of using a periscope is the ability to observe from below, a technique often referred to as "under-the-keel" or "under-the-hull" reconnaissance. In this scenario, a submarine's periscope can rise just above the waterline, and the officer can look up and observe the underwater parts of a ship, including propellers, rudders, and other critical components. This form of reconnaissance is invaluable, as it can provide details that might not be observable from a high vantage point.

The Practicalities and Limitations

Despite its advantages, the periscope has significant limitations. As mentioned, visibility can be limited to just the disturbed water or the bottom of waves. Observations are also highly dependent on the surrounding conditions, such as light, turbulence, and the presence of other objects on the water surface. Additionally, periscopes can sometimes be detected by enemy radar or other surveillance methods, making their use critical only in certain, carefully planned operations.

Modern Innovations and Alternatives

With the advancement of technology, many of these functions now fall under the purview of advanced sonar systems, thermal imaging, and other non-optical methods. However, the periscope remains a symbol of submarine operations and a testament to the ingenuity of naval engineers.

While the periscope's days as a primary observation tool may be numbered, it remains an important piece of naval history and a fascinating subject for those interested in the intricacies of submarine operations. The periscope represents a significant step in the ongoing evolution of naval technology, from the early 20th-century optic tubes to the sophisticated systems of today.