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27-491: At least 2 British ships have been named SS Otranto after the Strait of Otranto between Italy and Albania. SS Otranto – 1909 ship that served as an armed merchant cruiser and troop ship during World War I before being wrecked in 1918. RMS  Otranto  (1925) – ocean liner that served during World War II as a troop transport and Landing ship, infantry before she

54-407: 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 . The modern jetboat was developed by New Zealand engineer Sir William Hamilton in

81-571: A jetboat expedition, titled "Ocean to Sky", from the mouth of the Ganges River to its source. One of the jetboats was sunk by a friend of Hillary. The fuel efficiency and performance of a jetboat can be affected by anything that disrupts the smooth flow of water through the jet unit. For example, a plastic bag sucked onto the jet unit's intake grill can have quite an adverse effect. Another disadvantage of jetboats appears to be that they are more sensitive to engine/jet unit mismatch, compared with

108-546: A shallow-angled (but not flat-bottomed) hull to improve its high-speed cornering control and stability, while also allowing it to traverse very shallow water. At speed, jetboats can be safely operated in less than 7.5 cm (3 inches) of water. One of the most significant breakthroughs, in the development of the waterjet, was to change the design so it expelled the jetstream above the water line, contrary to many people's intuition. Hamilton discovered early on that this greatly improved performance, compared to expelling below

135-402: A small nozzle at high velocity to push the boat forward. Steering is accomplished by moving this nozzle to either side, or less commonly, by small gates on either side that deflect the jetstream. Because the jetboat relies on the flow of water through the nozzle for control, it is not possible to steer a conventional jetboat without the engine running. Unlike conventional propeller systems where

162-512: A specific need for a propulsion system to operate in very shallow water, and the waterjet proved to be the ideal solution. The popularity of the jet unit and jetboat increased rapidly. It was found the waterjet was better than propellers for a wide range of vessel types, and waterjets are now used widely for many high-speed vessels including passenger ferries, rescue craft, patrol boats and offshore supply vessels. Jetboats are highly manoeuvrable, and many can be reversed from full speed and brought to

189-431: A stop within little more than their own length, in a manoeuvre known as a "crash stop". The well known Hamilton turn or "jet spin" is a high-speed manoeuvre where the boat's engine throttle is cut, the steering is turned sharply and the throttle opened again, causing the boat to spin quickly around with a large spray of water. There is no engineering limit to the size of jetboats, though whether they are useful depends on

216-505: Is becoming increasingly popular around the globe), pilot boat operations, surf rescue , farming , fishing , exploration , pleasure boating , and other water activities where motor boats are used. Jetboats can also be raced for sport, both on rivers ( World Champion Jet Boat Marathon held in Mexico, Canada, USA and New Zealand ) and on specially designed racecourses known as sprint tracks. Recently there has been increasing use of jetboats in

243-527: Is different from Wikidata All set index articles Strait of Otranto Since ancient times, the Strait of Otranto was of vital strategic importance. The Romans used it to transport their troops eastwards. The legions marched to Brundisium (now Brindisi), had only a one-day sea voyage to modern Albania territory and then could move eastwards following the Via Egnatia . During World War I ,

270-522: Is impossible with a conventional single propeller. Unlike hydrofoils , which use underwater wings or struts to lift the vessel clear of the water, standard jetboats use a conventional planing hull to ride across the water surface, with only the rear portion of the hull displacing any water. With the majority of the hull clear of the water, there is reduced drag, greatly enhancing speed and maneuverability, so jetboats are normally operated at planing speed. At slower speeds with less water pumping through

297-418: The 127 metres (417 ft) long United States Littoral Combat Ship are among the biggest jet-propelled vessels as of 2020 . Even these vessels are capable of performing "crash stops". A conventional screw propeller works within the body of water below a boat hull, effectively "screwing" through the water to drive a vessel forward by generating a difference in pressure between the forward and rear surfaces of

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324-665: The barrage was notoriously ineffective against the German and Austrian U-boats operating out of the Adriatic, which were to plague the Allied powers for most of the war throughout the Mediterranean. In 1992, Albania and Italy signed a treaty that delimited the continental shelf boundary between the two countries in the Strait. Whatsoever the administration rights over the Strait were given to Albania not changing much from

351-447: The equivalent size waterjet would be too big to be practical. The vast majority of waterjet units are therefore installed in high-speed vessels and in situations where shallow draught, maneuverability, and load flexibility are the main concerns. The biggest jet-driven vessels are found in military use and the high-speed passenger and car ferry industry. South Africa's Valour-class frigates (approximately 120 metres or 390 feet long) and

378-407: The form of rigid-hulled inflatable boats and as luxury yacht tenders . Many jetboats are small enough to be carried on a trailer and towed by car. As jetboats have no external rotating parts they are safer for swimmers and marine life , though they can be struck by the hull. The safety benefit itself can sometimes be reason enough to use this type of propulsion. In 1977, Sir Edmund Hillary led

405-632: The former deal of Otranto. In 1997 and 2004, nearly 100 people died trying to illegally cross the strait following the 1997 unrest in Albania and poor economic conditions in the Tragedy of Otranto and the Karaburun tragedy . In 2006, the Albanian government imposed a moratorium on motor-powered sailing boats on all lakes, rivers, and seas of Albania to curb organized crime. The only exemption to

432-406: The inlet. This probably meant that disturbed water was entering the jet unit and reducing its performance, and the main reason why the change to above the waterline made such a difference. Applications for jetboats include most activities where conventional propellers are also used, but in particular passenger ferry services, coastguard and police patrol, navy and military, adventure tourism (which

459-416: The jet again, which may cause aeration problems, or increase reverse thrust. Steering is still available with the reverse deflector lowered so the vessel will have full maneuverability. With the deflector lowered about halfway into the jetstream, forward and reverse thrust are equal so the boat maintains a fixed position, but steering is still available to allow the vessel to turn on the spot – something which

486-448: The jet unit, the jetboat will lose some steering control and maneuverability and will quickly slow down as the hull comes off its planing state and hull resistance is increased. However, loss of steering control at low speeds can be overcome by lowering the reverse deflector slightly and increasing throttle – so an operator may increase thrust and thus control without increasing boat speed itself. A conventional river-going jetboat will have

513-491: The mid-1950s. His goal was a boat to run up the fast-flowing rivers of New Zealand that were too shallow for propellers. Previous attempts at waterjet propulsion had very short lifetimes, generally due to the inefficient design of the units and the fact that they offered few advantages over conventional propellers. Unlike these previous waterjet developments, such as Campini's and the Hanley Hydrojet , Hamilton had

540-404: The propeller blades and by accelerating a mass of water rearward. By contrast, a waterjet unit delivers a high-pressure "push" from the stern of a vessel by accelerating a volume of water as it passes through a specialised pump mounted above the waterline inside the boat hull. Both methods yield thrust due to Newton 's third law — every action has an equal and opposite reaction. In a jetboat,

567-402: The rotation of the propeller is reversed to provide astern movement, a waterjet will continue to pump normally while a deflector is lowered into the jetstream after it leaves the outlet nozzle. This deflector redirects thrust forces forward to provide reverse thrust. Most highly developed reverse deflectors redirect the jetstream down and to each side to prevent recirculation of the water through

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594-475: The rule are government-owned boats, foreign-owned boats, fishing boats, and jet boats . In 2010, the moratorium was extended until 2013. This article about a specific location in Vlorë County , Albania, is a stub . You can help Misplaced Pages by expanding it . This Apulia location article is a stub . You can help Misplaced Pages by expanding it . Jet boat A jetboat is a boat propelled by

621-494: The strait was of strategic significance. The Allied navies of Italy , France , and Great Britain , by blockading the strait, mostly with light naval forces and lightly armed fishing vessels known as drifters , hindered the cautious Austro-Hungarian Navy from freely entering the Mediterranean Sea , and effectively kept them out of the naval theatre of war. The blockade was known as the ' Otranto Barrage '. However,

648-413: The type of application. Classic prop-drives are generally more efficient and economical at low speeds, up to about 20 knots (37 km/h; 23 mph), but as boat speed increases, the extra hull resistance generated by struts, rudders , shafts and so on means waterjets are more efficient up to 50 knots (93 km/h; 58 mph). For very large propellers turning at slow speeds, such as in tugboats ,

675-412: The waterjet draws water from beneath the hull, where it passes through a series of impellers and stators – known as stages – which increase the velocity of the waterflow. Most modern jets are single-stage, while older waterjets may have as many as three stages. The tail section of the waterjet unit extends out through the transom of the hull, above the waterline. This jetstream exits the unit through

702-427: The waterline, while also providing a "clean" hull bottom (i.e. nothing protruding below the hull line) to allow the boat to skim through very shallow water. It makes no difference to the amount of thrust generated whether the outlet is above or below the waterline, but having it above the waterline reduces hull resistance and draught. Hamilton's first waterjet design had the outlet below the hull and actually in front of

729-577: Was scrapped in 1957. [REDACTED] [REDACTED] List of ships with the same or similar names This article includes a list of ships with the same or similar names. If an internal link for a specific ship led you here, you may wish to change the link to point directly to the intended ship article, if one exists. Retrieved from " https://en.wikipedia.org/w/index.php?title=SS_Otranto&oldid=843937923 " Categories : Set index articles on ships Ship names Hidden categories: Articles with short description Short description

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