Link history | Underwater Ghosts: The Encounter Between a Submarine and a Frogman

In December 1941, the Italian Navy submarine "Skăr" secretly sneaked to the outskirts of Alexandria, Egypt, where the British Navy's Mediterranean Fleet was stationed, and dropped three "pig" man-operated torpedoes piloted by frogmen. The Frogman maneuvered the torpedoes to follow the warship through the dense anti-submarine nets of the harbor, sinking the British Navy battleships Warrior and Queen Elizabeth, and injuring the tanker Saguna and the armed merchant ship Jervis Bay.

Submarines deliver frogmen to combat areas to carry out reconnaissance, surveillance, sabotage, anti-terrorism and other tasks, which originated in World War II as a combat style and became a real combat sample of the use of frogmen by special forces of various countries in the future.

Submarine and special forces frogs are both titled "underwater ghosts", and the combination of the two is an innate advantage of strong concealment and long maneuverability, but it also faces two major problems. First, the ability and quality of frog people are high. The structure of the seabed around the coast is complex, affecting the navigation and identification ability of frogmen and threatening their lives. The loss of body temperature and physical exertion in the water is much higher than that on land, coupled with the limited oxygen and combat equipment they carry, the stealth distance and duration of frogmen are further limited. In order to successfully carry out the mission, frogmen must also be proficient in blasting, reconnaissance and other skills. Second, there are high requirements for submarine combat performance. Water depths a few nautical miles from the shore are usually not enough to support the submarine navigation of large submarines, while mini-submarines are constrained by range and self-sustaining power, unable to perform ocean-going, long-term missions, and require strong intelligence and reconnaissance capabilities when selecting penetration points and planning routes.

With the development of science and technology, the above two major problems are no longer the bottlenecks restricting the development of this tactic. First, the frogman's individual comprehensive combat capability has been greatly improved. The first is the improvement of underwater gas supply devices, which are currently used by special forces of various countries with more fully enclosed circulating gas supply devices, which are highly concealed and have high gas utilization. The second is weapons and equipment, and now the frogman's firearms and ammunition for self-defense and combat have been developed to amphibious amphibious, communication coordination has underwater command and control systems, and is also equipped with underwater blasting, handheld sonar, navigators and other equipment. The perfection of diving theory, scientific and effective training and the research and development of advanced equipment make the frogman's individual comprehensive combat ability and World War II period indistinguishable. The second is the emergence of frogman transport boats, which makes up for the shortcomings of submarines in the "last kilometer". Subject to the structure of the seabed, environmental conditions such as water depth and submarine displacement, frogmen are often released at several nautical miles from the coastline, increasing the range and duration of the dive, and increasing the difficulty of release and recovery. The traditional frogman delivery method is to use the submarine's torpedo tube, the frogman first enters the torpedo tube from the submarine's internal hatch, and then closes the hatch to inject water and pressurize, so that the pressure in the tube and the water pressure outside the boat are balanced, and then open the outer hatch, climb out of the submarine, take the opposite way when recovering, or use the submarine escape capsule to release and recycle the frogman. Under these two delivery methods, frogmen can only carry a small amount of combat equipment, and cannot carry large size and large weight equipment, which is only suitable for small detachments to carry out combat tasks. To change this situation, the Frogman transport boat came into being.

The small frogman thrusters that were first introduced were similar to the human-operated torpedoes of the World War II period, small in size, light in weight, easy to enter and exit submarines, carrying 1 to 2 people, powered by batteries, with a speed of only 3 to 6 knots, and limited carrying capacity. Even so, its appearance has greatly increased the stealth distance and duration of the frogman, and saved the frogman's physical strength. In order to make up for the lack of range of the thrusters, countries have developed frogman transport boats. The volume of the transport boat is much larger than the propeller, there is a manned cabin that can accommodate 4 to 10 people, the speed is more than 6 knots, the range is more than 10 nautical miles, and it is equipped with navigation, communication, sonar and other systems, and some countries are even equipped with torpedoes, which can directly hit the target. Frogmen are more convenient for saving physical strength in the cabin, and the stealth time is generally about 4 hours.

The advent of frogman carriers greatly enhanced the flexibility of the tactic, which, in conjunction with nuclear submarines, allowed a special operations detachment of more than a dozen people to patrol underwater for two or three months. Taking the current more advanced US military Mk-8 Mod1 frogman transport boat as an example, the maneuver stage is fixed in the transfer compartment on the back deck of the Ohio-class nuclear submarine. The cabin is made of nuclear submarine pressure-resistant steel and is equipped with a pressurization, injection and drainage and lighting system. During the operation, the frogman entered the transfer compartment from the submarine's watertight door, completed the preparation for the dispatch, used the guide rail to detach the carrier from the submarine, and then sailed to the mission area, and after completing the task, it was recovered in reverse order. According to the US Marine Corps Times, since 2003, the US Navy SEALs carrying nuclear submarine-dropped transporters have secretly infiltrated into the Coast of Somalia and have successfully carried out more than ten reconnaissance and counter-terrorism missions. In 2017, the USS Ohio-class nuclear submarine "Michigan" carried the frogman carrier to Seoul, South Korea, to participate in the exercise, one of the courses is to carry frogmen to carry special operations. Russia's "Belgorod" nuclear submarine, Britain's "Astute" class nuclear submarine, France's "Barracuda" class nuclear submarine, etc. are all equipped with frogman transport boats or special forces underwater combat equipment, and the importance attached by various countries to frogman combat can be seen.

Although the functions of the conveyor boat are becoming more and more complete, the frogman's immersion in the sea water while sneaking will still limit the stealth time (this type of transport boat is called a wet frogman conveyor boat). To solve this problem, the U.S. military has developed dry frogman transport boats. The cabin is equipped with gas supply and temperature regulation devices, using a watertight and pressure-resistant structure, carrying 12 to 18 people, frogmen from the submarine into the tanker compartment without diving suits, wearing respirators, more conducive to maintaining physical and mental state. The carrier is equipped with sonar on the sides and front end, periscopes, communication antennas, positioning buoys, etc. on the top deck, equipped with a more advanced integrated navigation system, which can be said to be a miniature submarine dedicated to frogmen. In addition, countries have begun to develop a new generation of frogman transport boats, the new boat can switch between surface navigation and underwater stealth two modes, can be directly launched by surface ships, large transport aircraft and helicopters, using modular design, weapon modules, reconnaissance modules and other different mission loads on demand. Frogman carriers have evolved from initial power tools to underwater integrated special operations platforms, with more flexible tactical use.

Since its birth, the special operations tactic of submarine delivery frogman has undergone many war tests, and it is still active in regional local conflicts and various non-war military operations. For the foreseeable future, it will still occupy a place on the world military stage.

(China National Defense Daily, December 16, 2021, fourth edition)

Source: China National Defense Daily