Underwater television is any type of electronic camera that is located underwater in order to collect and display images is called underwater television. It must be packaged in a waterproof housing. The underwater camera may be packaged with its own recording device, or it can be attached to a television that is located on a ship, in a laboratory, or at a remote site. In the latter case, the images by the camera are called real-time images, as they are available at the same time that the camera is recording them. An underwater television may be used for sport, ocean exploration, industrial applications, or military purposes. Common imaged subjects are animals, coral reefs, underwater shipwrecks, and underwater structures such as piers, bridges, and offshore oil platforms.
During the day time and at minimal depths, underwater television can be used to view objects illuminated with natural sunlight. For nighttime viewing or at very deep depths, artificial lights must be used. Light in the ocean is reduced in intensity quite severely even in the clearest natural waters, a beam of blue or green light will be reduced in intensity by approximately 67% every 230 ft or 70 meters. Light that is propagating through an aqueous medium such as sea water or lake water will also be selectively reduced in intensity, based on wavelength. In most situations, the extreme reds and blues will be most severely attenuated, with the region of highest clarity being the yellow to blue-green wavelengths.
Modern advances in television cameras have opened up a host of applications for underwater viewing, such as standard-videos, charge-injection-device, silicon-intensified-target, or charge-coupled-device cameras. These cameras can be adapted for high frame rate, low light level, or underwater colour imaging. Computer modeling of underwater images can be used to predict the performance of an underwater imaging system in terms of range of viewing and quality of images as a function of the clarity of the water.
The most spectacular use of an underwater television system was the discovery of the lost luxury liner Titanic. In order to find the Titanic, which was located at a depth of approximately 16,000 ft or 4800 meters, an underwater television system that consisted of a video camera equipped with light was used.
Underwater Vehicle: A submersible work platform designed to be operated either remotely or directly is called underwater vehicle.
Development of underwater vehicle began before World War I with the surface-tethered diving bells and armoured diving suits. Both were intended to perform salvage tasks. Some of the bells could go to depths of several hundred feet and were equipped with external lights and a variety of tools.
Armoured suits were one-person submersibles in the general shape of a diving suit. Depth capabilities of 700 ft or 210 meters were possible since the operator/diver was not exposed to sea pressure. Bottom time at the work site was greatly increased over conventional diver capability. Problems with the flexibility and watertight integrity of the suits’ articulating joints limited use of these devices prior to World War II.
In the late 1920s, the United States scientists William Beebe developed the Bathysphere (deepsphere), a thick-walled steel ball lowered into the sea on a steel cable. The interior provided sufficient room for two crew members and their equipment. Three quartz glass windows permitted outside viewing and photography. The Bathysphere made 32 divers from 1930 to 1934 at Bermuda, ending with a dive to 3028 ft or 910 meters.
In 1950, an improved version, the Benthoscope, was developed by Beebe’s former engineer, Otis Barton. It was successfully tested off California to depths of 4500 ft or 1350 meters, but made few working dives.
Japan developed the Kuroshio for Oceanographic research in the early 1950s. retired in the 1960s, it was capable of diving to 650 ft or 200 meters. This was the world’s last operational bathysphere, although the diving bells of today are not much different in concept. It was not until 1948 that the first practical untethered underwater vehicle was tested: the bathyscaph (deepship) FNRS-2, invented by Swiss physicist Auguste Piccard. It was basically an underwater free balloon, with buoyancy provided by lighter-than water aviation gasoline, contained in a large steel float (balloon). A thick-walled spherical cabin for two or three crew members was suspended beneath the float.
The float moved vertically by adding weight (seawater) or by dropping steel ballast pellets. Small electric motors fitted with propellers provided limited horizontal movement.
From 1950 to 1978, the French Navy developed and operated bathyscalphs FNRS-3 (1953) and Archimede (1963). In 1953, Piccard built his last bathyscaph, Trieste, which was sold to the U.S. Navy in 1958. In 1960, a Navy expedition took Trieste to a depth of 35,800 ft or 10,700 meters at Challenger Deep near the island of Guam in the western Pacific, the deepest place in the world ocean. After the original Trieste’s retirement in 1963, the Navy built two improved bathyscaphs, both called Trieste II. Each had a maximum depth capability of 20,000 ft, or 6000 meters.
Archimede retired in 1978, the last crewed submersible in the world capable of diving to the deepest place in the sea. Four years later, Trieste II was retired, it was the last operating bathyscaph in the world. These deep submersible vehicles served 35 years, much of this time there were the only way to work in the deep ocean. During the 1960s and early 1970s, divers and crewed submersibles dominated the underwater scene. However, new vehicles were under development in research laboratories during this time, including the Remotely Operated Vehicle (ROV) and tethered, crewless vehicles controlled from the surface of the sea. By the 1970s, the autonomous underwater vehicle (AUV) essentially an underwater robot, was under development.
Almost all the early submersibles were developed by navies, the U.S. Navy in particular. Military missions and related science needs were the primary forces driving research on underwater techniques during this period. Civil applications were stimulated by the steep oil price increases of the early 1970s, which led to increased offshore oil and gas production activity. Opening new resources areas such as the North Sea accelerated development of new tools and techniques for conventional deep-sea divers.
Today, crew submersibles are used in limited numbers for underwater work. But they will always be needed. The most numerous family of submersibles are remotely operated, with an estimated 3000 having been built since 1970. Now autonomous underwater vehicles are practical tools for underwater work. Their numbers will increase in future years.
Types: Underwater Vehicles are grouped into three categories: deep submersible vehicles (DSVs), Remotely Operated Vehicles (ROVs), and Autonomous Underwater Vehicles (AUVs). There are also hybrid vehicles which combine two or three categories on board a single platform. Within each category of submersible there are specially adapted vehicles for specific work tasks. These can be purpose-built or modifications of standard submersibles.
