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A semi-submarine (semi-sub) is a surface vessel that is not capable of diving, but has accommodation space below the waterline featuring underwater windows. [1] The watercraft is similar to glass-bottom boats, but with deeper draft. Both types of boats are mainly used to provide sight-seeing trips for tourists in clear, calm, and often shallow, waters.
The most common design is similar to a small ship. The passenger cabin is deep within the hull, a few meters below the waterline. The cabin is equipped with large underwater windows, so the passengers can observe the marine environment that is passed during the voyage.
There are significant engineering differences between a true submarine and a semi-submarine. Submarines are human-occupied pressure vessels subjected to high external pressure, while semi-submarines are only subjected to the same pressures as other surface vessels of similar draft operating in similar conditions. As the hydrostatic pressure close to the water surface is relatively low, the viewing windows can be large. In some designs, the windows enclose the majority of the immersed hull. Passengers can climb up from the submerged cabin to the unsubmerged deck level at any time.
Since the semi-sub interior is always open to the atmosphere, no special measures must be taken to assure a supply of breathable air to its occupants.
Semi-submarines can be used for research, but they are most commonly used in the tourism business. However, large tourism-oriented semi-submarines should not be confused with narco-submarines which are smaller home-made semi-submarines used to smuggle drugs.
Semi-submarines do not have an international classified status. Their operating range from the native port might be limited by the local authorities.
A hull is the watertight body of a ship, boat, or flying boat. The hull may open at the top, or it may be fully or partially covered with a deck. Atop the deck may be a deckhouse and other superstructures, such as a funnel, derrick, or mast. The line where the hull meets the water surface is called the waterline.
A submarine is a watercraft capable of independent operation underwater. It differs from a submersible, which has more limited underwater capability. The term is also sometimes used historically or colloquially to refer to remotely operated vehicles and robots, as well as medium-sized or smaller vessels, such as the midget submarine and the wet sub. Submarines are referred to as boats rather than ships irrespective of their size.
A yacht is a sailing or power vessel used for pleasure, cruising, or racing. There is no standard definition, though the term generally applies to vessels with a cabin intended for overnight use. To be termed a yacht, as opposed to a boat, such a pleasure vessel is likely to be at least 33 feet (10 m) in length and may have been judged to have good aesthetic qualities.
A jetboat is a boat propelled by a jet of water ejected from the back of the craft. Unlike a powerboat or motorboat that uses an external propeller in the water below or behind the boat, a jetboat draws the water from under the boat through an intake and into a pump-jet inside the boat, before expelling it through a nozzle at the stern.
A bathyscaphe is a free-diving, self-propelled deep-sea submersible, consisting of a crew cabin similar to a Bathysphere, but suspended below a float rather than from a surface cable, as in the classic Bathysphere design.
Seaview, a fictional nuclear submarine, was the setting for the 1961 motion picture Voyage to the Bottom of the Sea, starring Walter Pidgeon, and later for the 1964–1968 ABC television series of the same title. In the film, Seaview fires a ballistic missile with a nuclear warhead to extinguish the Van Allen belt that was set on fire by a space cataclysm.
A submersible is an underwater vehicle which needs to be transported and supported by a larger watercraft or platform. This distinguishes submersibles from submarines, which are self-supporting and capable of prolonged independent operation at sea.
This glossary of nautical terms is an alphabetical listing of terms and expressions connected with ships, shipping, seamanship and navigation on water. Some remain current, while many date from the 17th to 19th centuries. The word nautical derives from the Latin nauticus, from Greek nautikos, from nautēs: "sailor", from naus: "ship".
Hull speed or displacement speed is the speed at which the wavelength of a vessel's bow wave is equal to the waterline length of the vessel. As boat speed increases from rest, the wavelength of the bow wave increases, and usually its crest-to-trough dimension (height) increases as well. When hull speed is exceeded, a vessel in displacement mode will appear to be climbing up the back of its bow wave.
Finding Nemo Submarine Voyage is an attraction in the Tomorrowland area of Disneyland Park in Anaheim, California. It opened on June 11, 2007. Based on the characters and settings of the 2003 Disney·Pixar film Finding Nemo, it is a re-theming of the classic Submarine Voyage attraction that operated from 1959 to 1998.
In sailing vessels, the head is the ship's toilet. The name derives from sailing ships in which the toilet area for the regular sailors was placed at the head or bow of the vessel.
The Submarine Voyage was an attraction at Disneyland in Anaheim, California. The attraction features vehicles designed to resemble submarines. It first opened on June 14, 1959, as one of the first rides to require an E ticket. It was part of a major expansion of Tomorrowland, which included the Matterhorn Bobsleds roller coaster, an expanded version of Autopia, the Disneyland Monorail, and the Motor Boat Cruise. The Submarine Voyage closed on September 8, 1998; at that time, it was reported that the attraction would reopen with a new theme by 2003, but that did not occur. The attraction ultimately reopened in June 2007 themed to Disney and Pixar's Finding Nemo, and now operates as Finding Nemo Submarine Voyage.
A ballast tank is a compartment within a boat, ship or other floating structure that holds water, which is used as ballast to provide hydrostatic stability for a vessel, to reduce or control buoyancy, as in a submarine, to correct trim or list, to provide a more even load distribution along the hull to reduce structural hogging or sagging stresses, or to increase draft, as in a semi-submersible vessel or platform, or a SWATH, to improve seakeeping. Using water in a tank provides easier weight adjustment than the stone or iron ballast used in older vessels, and makes it easy for the crew to reduce a vessel's draft when it enters shallower water, by temporarily pumping out ballast. Airships use ballast tanks mainly to control buoyancy and correct trim.
A moon pool is an equipment deployment and retrieval feature used by marine drilling platforms, drillships, diving support vessels, fishing vessels, marine research and underwater exploration or research vessels, and underwater habitats. It is also known as a wet porch. It is an opening found in the floor or base of the hull, platform, or chamber giving access to the water below. Because of its stable location, it safely allows technicians or researchers to lower tools and instruments into the sea.
A submarine hull has two major components, the light hull and the pressure hull. The light hull of a submarine is the outer non-watertight hull which provides a hydrodynamically efficient shape. The pressure hull is the inner hull of a submarine that maintains structural integrity with the difference between outside and inside pressure at depth.
A teardrop hull is a submarine hull design which emphasizes submerged performance over surfaced performance. It was somewhat commonly used in the early stages of submarine development, but was gradually abandoned in the early 20th century in favour of designs optimized for high performance on the surface as a result of changes in operational doctrine. Although naval doctrine changed, design practices remained until the later parts of World War II when the German Kriegsmarine suffered ever-growing losses of submarines in the Battle of the Atlantic.
The draft or draught of a ship's hull is the vertical distance between the waterline and the bottom of the hull (keel). The draught of the vessel is the maximum depth of any part of the vessel, including appendages such as rudders, propellers and drop keels if deployed. Draft determines the minimum depth of water a ship or boat can safely navigate. The related term air draft is the maximum height of any part of the vessel above the water.
Diving support equipment is the equipment used to facilitate a diving operation. It is either not taken into the water during the dive, such as the gas panel and compressor, or is not integral to the actual diving, being there to make the dive easier or safer, such as a surface decompression chamber. Some equipment, like a diving stage, is not easily categorised as diving or support equipment, and may be considered as either.
This glossary of nautical terms is an alphabetical listing of terms and expressions connected with ships, shipping, seamanship and navigation on water. Some remain current, while many date from the 17th to 19th centuries. The word nautical derives from the Latin nauticus, from Greek nautikos, from nautēs: "sailor", from naus: "ship".
Submarine rescue is the process of locating a sunk submarine with survivors on board, and bringing the survivors to safety. This may be done by recovering the vessel to the surface first, or by transferring the trapped personnel to a rescue bell or deep-submergence rescue vehicle to bring them to the surface. Submarine rescue may be done at pressures between ambient at depth, and sea level atmospheric pressure, depending on the condition of the distressed vessel and the equipment used for the rescue. Self-rescue of submarine personnel by buoyant free ascent at ambient pressure is considered submarine escape. Survivors may require recompression treatment for decompression illness.