We are publishing the final article of the series prepared by our regular author Nikolai Vladimirovich Korytov, dedicated to one of the most interesting pages of modern shipbuilding. We remind you that his articles were devoted to the same topic of creating high-speed double-hull sea vessels: “Cutting the Wave” - in “KiYa” No. 157 and “High-Speed Vessels with Unusual Water Jet Installations” in No. 167. The author quite rightly notes that today it seems the most the promising way is precisely combination - a combination of different ways to increase operating speeds maritime assets transport.
Hovercraft catamarans
On the way to the site there is free space to rest and freedom of movement. Before joining Brittany Ferries, she carried the Olympic torch during the Sydney Olympics relay. She also helped assist tsunami relief efforts. Leonora Christina is a fast ferry passenger steamer built by Australian shipbuilder Austal at the Western Australian Shipyard in Henderson. Each vessel costs about 60 million euros. It was handed over to its owner in May.
The experience of world shipping indicates the successful operation of high-speed sea catamarans. Double-hulled vessels of various types continue to be built in large quantities. Thus, in the period from 1990 to 1995 alone, the number of sea catamarans put into operation increased from 312 to 500 units; At the same time, the share of catamarans in the total number of sea vessels built over the same five years increased from 34 to 42%. Australia occupies a leading position in the creation of vessels of this type - about a quarter of the total number of catamarans built in the world was built at its shipyards. Quite a few double-hulled vessels were also built in Norway, Japan and Finland. The architectural and structural type of double-hulled vessels is constantly being improved, their cargo and passenger capacity is increasing, speed characteristics and seaworthiness are improving, and more high level comfort for passengers. A characteristic trend is a steady increase in sailing speeds: the majority of built sea catamarans have operating speeds in the range of 38-42 knots, and some have reached a maximum speed of 45-50 knots. Thus, thanks to the use of double-hulled vessels, the 40-knot speed barrier in the development of the world transport fleet can be considered overcome. Recently, double-hulled hybrid type vessels have been increasingly being designed and built in a number of countries. On such vessels, in order to completely reduce movement resistance and increase seaworthiness, combined hull contours are used, and they also use unconventional hydrodynamic principles of support - using hydrofoils or an air cushion.
Leonora Christina was designed to meet strict Danish environmental regulations covering noise, wave and exhaust emissions limits. The aluminum superstructure contains anti-vibration shock-absorbing mounts. The entire ferry is broadly classified into five compartments, including three vehicle decks and two passenger decks. Bays include car garage, bridge deck, mezzanine deck, main deck and upper deck. Three car decks can be accessed via the bow and stern ramps.
Vehicles can be placed in garage garage main vehicle and two upper decks, making loading and unloading easier. These three car decks can accommodate 357 cars. Passenger seating is provided on the bridge deck along with lounge areas that are accessible via a large staircase.
1. Catamarans with high aspect ratio hulls and V-shaped contours
The main component of the total resistance of a high-speed vessel is wave resistance, caused by the occurrence of ship waves under the influence of gravity of liquid particles. The wave formation caused by the movement of the vessel consists of bow and stern groups of divergent and transverse waves, and the main role in creating resistance is played by transverse waves . As the vessel moves, an overlap occurs - interference of these groups of waves. At certain speeds, unfavorable interference occurs, as a result of which the amplitude of the resulting waves increases and the wave resistance increases; at other speeds, on the contrary, favorable interference of the bow and stern groups of waves is observed, i.e. there is a decrease in the intensity of wave formation behind the stern and the overall value of wave resistance Rв decreases. The pattern of wave formation behind the hull of a moving vessel, and therefore the value of Rв, depend primarily on the speed of movement, therefore the wave resistance is modeled using the Froude number Fr = v/ gL. At low speeds, determined by the Froude number 0.10 е 0.15, there is practically no wave resistance. With increasing speed, it increases sharply and at Fr ~ 0.5 a clearly defined maximum Rв is observed - the problem arises of overcoming the so-called “wave barrier” (for this it is necessary to use various hydromechanical and structural means). The wave resistance also very significantly depends on the shape of the hull contours and the ratio main dimensions of the vessel. In this case, the predominant influence on Rв is exerted by: the coefficient of the overall completeness of the vessel d; relative hull length L/B or L/V1/3 (where V is the volumetric displacement of the vessel); relative width of the H/T, as well as the contours of the vessel at the extremities. In this case, an increase in the relative length contributes to a decrease in Rw, the greater the higher the Froude number. Wave resistance decreases intensively with increasing depth of immersion of the body (vessel hull). It is known that submarines in a submerged position do not experience wave resistance. The relative depth of immersion of the body, during movement at which there will be no wave formation, can be determined from the condition H/L Ё 1.5 Fr–0.15. And finally, a hydromechanical interaction between the wave systems of both hulls occurs on a moving catamaran. If their interaction is favorable, a slight reduction in Rв can be achieved, the magnitude of which also depends on the contours of the hulls and their horizontal transverse clearance. In order to increase the propulsive and seaworthy qualities of catamaran hulls, they are usually made with a large relative elongation lк/bк. In this regard, it is worth noting, for example, a series of six vessels from the Australian company InCat. On the largest catamaran of this series, “InCat 050”, built in 1998, the hulls have a very high aspect ratio - 19. 1, which made it possible to significantly reduce wave drag at full speed and ensure an operating speed of 42 knots with a relatively moderate power plant. An even larger catamaran with “ultra-narrow” hulls having a relative aspect ratio of 21.7 is under construction. With main dimensions of 120-29-4.7 m, the length of the hulls along the vertical line is 102.3 m, and the width is 4.7 m. With a deadweight of 1200 tons and a gas turbine power plant with a power of 4-13100 kW, the vessel will be able to reach a speed of 51 knots, having on board 1200 passengers and 460 cars. Japanese company “IHI” has developed a standard range of catamarans with “ultra-thin” hulls of the “SSTH” type (Super Slender twin hull) with a length from 30 to 200 m. One of the largest catamarans in this series, having main dimensions of 153.5-27.5 m, will be able to reach speed 37 knots with a two-shaft power plant with a total power of 41,200 kW. It is known that when moving in rough seas, the ship experiences vertical, roll and pitching, which results in flooding of the deck and superstructures, the danger of slamming (i.e. hydrodynamic impacts of the hull on the oncoming wave ) and loss of stability. All these phenomena significantly worsen the comfort of passengers and the habitability of the crew. The impact of waves causes accelerations (overloads), which are usually estimated as fractions of the acceleration free fall g (if the magnitude of these overloads, measured at the vessel’s center of gravity, is below 0.2g, the vessel’s seaworthiness is assessed as sufficient). In addition, in rough conditions, the vessel’s performance deteriorates due to an increase in movement resistance and a decrease in the efficiency of the propulsors. In some cases, there is a need to deliberately reduce the speed of the vessel or even change its course. One of the constructive means of increasing the seaworthiness of catamarans is the use of “deep V” type contours, which until recently were widely used only in boat building. Compared to conventional low-rise and round-chine hulls, V-shaped contours, which soften impacts on waves, can significantly reduce the likelihood of slamming and increase the vessel’s stability on course; In addition, its flooding with water decreases and stability increases. An important operational advantage of V-shaped contours is the reduction of the actual loss of speed when sailing in rough seas. In order to further increase operational efficiency, most high-speed catamarans built recently are equipped with a special system for stabilizing the vessel's movement in rough conditions MDS (Motion Damping System). This system includes T-shaped hydrofoils with flaps installed in the bow end of each hull, active trim tabs on the transom - controlled transom plates, as well as spoilers along the perimeter of the hulls. As experience has shown, the MDS system provides moderation (by 50%) of the amplitudes of pitching and movements during vertical pitching; reduction of overloads by 1.5-2 times, as well as simplification of trim in rough conditions. As a result, the level of comfort on board is significantly increased. In particular, such a system was used on a passenger catamaran with sharp chine lines, built at the Ukrainian shipyard “More” (Feodosia). The catamaran with a displacement of 77 tons has smooth dimensions of 30.4-8.6-0.9 m and a capacity of 200 passengers. The two nose T-wings are made of titanium alloy. Interceptors are installed in the stern. The diesel power plant with a power of 4ґ788 kW operates on two propellers, providing a speed of 45 knots.2. Catamarans with a relatively small waterline area
As noted above, a reduction in wave resistance can also be achieved by deepening the floating volume of the vessel, i.e. creating a catamaran with subsurface hulls of the SWATH type (SMPV). This modification has also been developing recently. Structurally, the SMPV consists of two underwater cigar-shaped hulls with a large relative elongation, each of which is connected to the surface part of the vessel, which looks like a load-bearing platform, using one or two vertical posts. This platform houses the transported cargo, premises for passengers, and equipment. The underwater hulls house the power plant, ship systems and devices, ballast and fuel tanks. A characteristic feature of SMPV catamarans is the small area of the active waterline - it is determined only by the cross-sectional area of the water level of the supporting struts. Their main operational advantages are high seaworthiness and comfort, reduced speed loss in rough seas. These positive traits are caused by the small disturbing effect of waves on the ship (due to the reduced waterline area) and large values of the natural periods of vertical and longitudinal pitching, as a result of which the ship is less susceptible to slamming and flooding. However, SMPVs have a larger specific wetted surface area of their hulls compared to conventional catamarans, and this leads to an increase in friction resistance. In terms of energy characteristics, such vessels can be competitive with other multihulls only at sufficiently high speeds at which wave drag becomes the main component of total drag. For catamarans of the SMPV type, a reduction in wave resistance is achieved by deepening the hulls and using favorable interference - the superposition of wave systems. Recently, double-hulled vessels with partial use of the SMPV concept have been designed and built as hybrid catamarans. Such vessels are called “semi-SWATH”. Structurally, they are made with a reduced hull width in the area of the operational waterline. A number of fairly large catamarans have been designed and built using this principle in Norway, Denmark and Australia. Of significant interest are the hybrid catamarans “HSS.1500” and similar, but smaller in size, type “HSS.900”. The complex of structural and hydromechanical means used on these vessels caused a significant reduction in wave resistance at the design speed (40 kts) and an increase performance qualities. We note the unusual shape of the hull contours with a large relative elongation, the reduced (compared to conventional catamarans) area of the active waterline, the use of bow bulbs, as well as the installation of active roll dampers and bow thrusters on both hulls. The maneuverability of catamarans has been improved, the level of vibrations and overloads from the effects of waves, as well as noise in passenger cabins has been structurally reduced. As shown by the analysis of tests of the head catamaran “Stena Explorer” (type “HSS.1500”), its Froude number is 0.58 (for ships type “HSS.900” it is even greater and equal to 0.7). Thus, we can conclude that the design operating mode of these vessels, thanks to the use of a number of new solutions, falls in the region that is supercritical in terms of wave resistance (i.e., higher than Fr ~ 0.5). This is also facilitated by the increased power supply of the vessel (the total power of the main power plant is 68,000 kW) and high efficiency multi-shaft water-jet propulsion unit. Danish catamarans “Mai Mols” and “Mie Mols” of the “Seajet-250” type, which use the same semi-SMPV concept, are successfully operating. These ferry-type vessels have the following main characteristics: main dimensions - 76.12-23.4-3.36 m; deadweight - 250 tons; capacity - 450 passengers and 120 cars. A two-shaft gas turbine power plant with a total power of 24,800 kW, which drives four KaMeVa water jets, provides an operating speed of 43.6 knots and a maximum speed of 46.4 knots. The welded hulls are made of aluminum. In the area of the operational waterline they are partially narrowed, which led to a slight decrease in the areas of the waterlines. The hulls are designed with high aspect ratio and a bulbous bow, which also helps reduce wave drag at design speed. It is noted that the applied solutions resulted in a 50% reduction in vertical and longitudinal movements and overloads during operation in rough seas. Thanks to the additional buoyancy of the connecting bridge and the division of the hulls into waterproof compartments, the vessel's unsinkability and emergency stability are ensured when both hulls are flooded by 1/3 of their length. Additional resistance when sailing in rough seas does not exceed 4-6%; the vessels maintain their design speed when operating on waves up to 2.5 m high. The semi-SMPV concept is also used on several “Auto Express 82” catamarans built in Australia. These are the ferry ships “Felix” and “Dolphin”, having main dimensions - 82.3ґ23.0ґ2.7 m; deadweight - 320 t; capacity - 676 passengers and 156 cars; a four-shaft water-jet installation of the “KaMeVa 112” type, driven by four diesel engines with a total power of 24,000 kW, provides an operating speed of 40.5 knots and a maximum speed of 41.5 knots.3. Catamarans with unconventional maintenance principles
The majority of catamarans built and currently being designed are displacement-type vessels, the buoyancy of which is ensured by hydrostatic (Archimedean) support force. It is known that as the speed of movement increases, the magnitude of this force decreases, since more and more important role hydrodynamic support forces. There are various means of practically implementing the hydrodynamic principle of maintenance. For this purpose, planing or semi-planing hull contours are used, and recently, load-bearing hydrofoils have been used, which make it possible to lift (or lift) the hull out of the water and thereby reduce the resistance to movement. Lifting a vessel from the water can also be carried out using aerostatic forces created by an air cushion. Hydrofoil catamarans. The wing device necessary for the vessel to move in foil mode must ensure that the vessel quickly reaches the wings, is stable and safe movement it not only in calm water, but also in rough water (at a given wave height), to maintain a constant lifting force of the wings in a wide range of speeds. Of course, it must be simple and reliable in operation. Most of the built sea catamarans-SPCs use deep-submerged, automatically controlled hydrofoils (AUK). The constancy of the lifting force of these wings is ensured by changing the angle of attack of the mechanical flaps by turning them using automatic system. As operating experience has shown, AUPK not only provide an increase in speed, but also can significantly reduce the harmful effects of pitching and increase comfort. Some PDAs use swept-back wings. Giving the wing a sweep delays the appearance of cavitation (it occurs at higher speeds), increases the ship's course stability and its seaworthiness. The speed corresponding to the moment the hull lifts off the water for most SPK catamarans is within 0.5 - 0.6 of the full speed. The Norwegian company “Westmarin West AS” built the high-speed CPC “Foilcat 2900”, the wing structure of which consists of split bows and a solid stern (continuous) wings made of of stainless steel. The span of each bow wing is 2.5 m, and the stern one is 7.79 m. Both wings are flat and deeply submerged, and have a swept plan. The stern wing carries 60% of the ship's mass, and the rest of the load falls on the bow wings. Two pulling propellers with a diameter of 1.25 m are used as propulsors, power is transmitted from diesel engines to them through an angular gear. Of great interest is the high-speed SPK “Rainbow”, built in Japan by MNU. It uses a number of new technical solutions to ensure a comprehensive reduction in displacement, increasing the hydrodynamic efficiency of the wing structure and water-jet propulsors. A special feature of the hulls is the use of V-shaped contours over a significant part of their length, which helps to increase the seaworthiness of the vessel. The housings are made of aluminum, and the design includes additional elements to reduce vibration and noise levels in passenger cabins (up to 76 dB). The wing device consists of two stainless steel AUPCs identical in all characteristics. The span of each wing is 12.8 m. The end sections of the wings are solid, and the rest is hollow. To ensure stability of movement, it is installed special system wing control APF (Auto Pilot on Foils). The propulsion unit consists of four high-speed lightweight diesel engines of the “S16R-MTK-S” brand, with increased performance characteristics, and two MWJ-5000A water jets developed by Mitsubishi. The blade mechanism of this water jet, unusual in type and design, having a cascade-type impeller with two rows of blades, is capable of developing additional thrust to overcome the “hump” of resistance when reaching the wings. Controllability and maneuverability are ensured by the reversible steering device of the water jets, as well as by the flap system installed on the struts of the bow wing. Another Japanese company “Hitachi Zosen”, continuing work on the creation of new and increasingly advanced catamarans, built the head SPK of the “Superjet-40” type. with a displacement of 300 tons and a speed of 45 knots. This is a further development of the previously built series of “Superjet-30” type ferries: dimensions and passenger capacity have been increased (up to 300 people); the use of a more powerful power plant made it possible to increase the speed by 7 knots. Two AUPK are located between buildings with V-shaped contours. Four diesel engines (two per hull) power two water jets. Marked increased level comfort, good seaworthiness and maneuverability of the SPC. The design and construction of double-hull SPCs are also carried out in South Korea. Thus, back in 1993, the company “Huindai Heavy Ind” built the first PDA, having main dimensions - 45.0-11.4-1.6 m and a passenger capacity of 300 people. The wing device consists of two AUPK. A two-shaft diesel power plant with a total power of 8210 kW provides an operating speed of 40 knots. Based on the successful operating experience of this catamaran, a design for a larger SPC with a length of 80 m (deadweight 240 tons), designed to carry 630 passengers and 160 cars, was developed. Four gas turbines with a total power of 28,000 kW, powered by two water jets, provide a speed of 45 knots. Note that the displacement of SPCs already in operation, as a rule, does not exceed 300 tons. The creation of larger catamarans on wings, as experts note, is problematic, since the dimensions and weight of the wing device increase significantly; in addition, there are design difficulties in implementing automation of wings so large sizes. That's why when we're talking about Regarding larger catamarans, hydrofoils today are considered not as a means of increasing speed, but only as the main part of the system for stabilizing the motion and trim of the vessel (see above about the MDS system). Hovercraft catamarans. Two fundamentally different types of hovercraft are known: amphibious, the hull of which can be completely detached from the water when moving, so that the vessel is able to go ashore, and non-amphibious, or skeg-based, with the hull not completely detached from the water, having rigid side railings (skegs) air cushion zones. The first small-sized skeg hovercraft were built in the 60s, including in our country; their speed was 30-40 knots. The experience of creating and operating these skeg hovercrafts has recently been used to develop projects and build increasingly larger hovercraft catamarans (hovercraft). Each hull of such hovercraft consists of a main part and skegs extending from it down the sides - narrow hulls, the width of which is usually less than half the width of the main part. On small-tonnage hovercrafts, “narrow skegs” are used, and on medium-tonnage and large vessels, skegs are made in the form of volumetric displacement structures. These skeg-hulls not only enclose the airspace area, but also ensure the buoyancy and stability of the catamaran, its general and local strength; serve as a volume for accommodating engines and propulsors. On the hovercraft bodies in a static position, a hydrostatic (Archimedean) supporting force arises Ygs = 2r · g · Wsk, (where Wsk is the immersed volume of one skeg), and when moving, some hydrodynamic lifting force also arises. A distinctive feature SVP is the presence of a special lifting complex designed to create and maintain a VP under the bottom of the main part of the hulls. The resultant of the static air pressure on the bottom part of the body is the aerostatic lift force of the hovercraft, which is determined by the expression Yaс = Рвп · Sвп, (where Рвп - air pressure in the cushion; Sвп - cushion area). Thus, the total supporting force of the catamaran will be equal to Y = Ygs + Yaac. On constructed hovercrafts, 80-85% of the total force supporting Y falls on Yac and 15-20% on Ygs. Important structural element double-hull SPC is a flexible enclosure of the air cushion area at the extremities. It must be sufficiently flexible and have a special shape that provides the least hydrodynamic resistance. The above-mentioned features of the hydro-aerodynamic configuration of the hovercraft necessitate the need for a separate power plant to create and maintain an air cushion; on built and designed catamarans, its power is 25-30% of the total power of the ship's power plant. High-speed light diesel engines and gas turbines are used as the main engines on the hovercraft. various combinations, as propellers - propellers of various types (including CV propellers, CPV and supercavitating ones, designed to work in conditions of highly developed cavitation) and water jets. Characteristic is the widespread use of multi-shaft water-jet installations with increased energy characteristics. This is due to the advantages of water cannons compared to propellers, such as ease of arrangement in narrow skegs (hulls), structural simplicity and increased reliability of operation, the possibility of reducing the vessel's draft, reduced noise and vibration levels of the hull, high maneuverability of a water-jet vessel. Analysis of operating experience indicates the prospects for the further development of hybrid hovercraft catamarans, providing an increased level of comfort. There is a low exposure of the vessel to the influence of wind and sufficient stability on the course, relatively small overloads from the impact on the vessel sea waves, the absence of high-frequency noise, which is created by air propellers on amphibious hovercraft. The largest catamaran of this type is the technosuperliner TSL-A “Hisho”, developed under the Japanese program for creating high-speed RO-RO ferries. This ferry has main dimensions of 125ґ27ґ4.7/1.5 m (the draft of 1.5 m corresponds to the hovercraft mode); payload 1100 tons. The propulsion power plant, consisting of two gas turbines of the LM 1600 type with a total power of 26,200 kW, operates on four water jets, providing a speed of 42-50 knots. A diesel power plant consisting of four 4410 kW engines drives fans to create and maintain air power.We are publishing the final article of the series prepared by our regular author Nikolai Vladimirovich Korytov, dedicated to one of the most interesting pages of modern shipbuilding. We remind you that his articles were devoted to the same topic of creating high-speed double-hull sea vessels: “Cutting the Wave” - in and “High-Speed Vessels with Unusual Water Jet Installations”. The author quite rightly notes that today the most promising way seems to be combination - a combination of various ways to increase the operating speeds of marine transport vehicles.
Passenger facilities include a fully equipped area Catering, bar, children's rooms, shopping area and play area for children. Leonora Cristina can accommodate 30 to 35 crew members. The gearbox is waterjet coupled via a carbon fiber shaft.
How to use the riders' experience?
The powertrain also includes an autopilot system. Fuel consumption is 4 tons per hour at full deadweight at a speed of 37 km. The power plant includes the injection system, combustion chamber, mill cycling and charge air cooler. Two 230 kW track generators are installed in the hull to produce electricity.
The experience of world shipping indicates the successful operation of high-speed sea catamarans. Double-hulled ships of various types continue to be built in large numbers. Thus, in the period from 1990 to 1995 alone, the number of sea catamarans put into operation increased from 312 to 500 units; At the same time, the share of catamarans in the total number of sea vessels built over the same five years increased from 34 to 42%. Australia occupies a leading position in the creation of vessels of this type - about a quarter of the total number of catamarans built in the world was built at its shipyards. Quite a few double-hulled ships were also built in Norway, Japan and Finland.
Key West Ferry to Dry Tortugas
Leonora Cristina's catamaran plans to join Willum Clausen's catamaran at the end of May. Willum Clausen has been working on the same route ever since. It is equipped with the latest and most advanced safety, navigation and communication equipment. Inspected by the Coast Guard and will do so every year.
Catamarans with unconventional maintenance principles
In addition, two generators are located below decks, as well as a variety of machinery and equipment to operate the vessel in the safest, quietest and most reliable manner. There is a spacious sun terrace with areas to stretch out and enjoy the sun and views. There is also a comfortable cocktail bar with a protective cover on the top floor.
The architectural and structural type of double-hulled ships is constantly being improved, their cargo and passenger capacity is increasing, their speed characteristics and seaworthiness are improving, and a higher level of comfort for passengers is being ensured. A characteristic trend is a steady increase in sailing speeds: the majority of built sea catamarans have operating speeds in the range of 38-42 knots, and some have reached a maximum speed of 45-50 knots. Thus, thanks to the use of double-hulled vessels, the 40-knot speed barrier in the development of the world transport fleet can be considered overcome.
The large, fully air-conditioned cabin has comfortable padded seating and big windows from all sides. Here you will find a full, modern galley offering a complimentary breakfast of fresh produce and juices at sea and a delicious full lunch at Fort Jefferson. Also on the main deck are storm water with water and three separate toilets. It is from this children's business The Yankee Navy was born. Today, Jerry, his wife Carol and family operate the Yankee fleet with ships located in Key West, Florida and Gloucester, Massachusetts.
The Yankee Fleet in Gloucester, Massachusetts has over 7 vessels and has grown to become New England's leader in whale watching, offshore fishing trips, education, whale conservation and maritime administration. Therefore our services correspond international standards quality, service, environmental awareness and reliability. No other fleet in Florida has this distinguished honor.
Recently, in a number of countries, double-hulled hybrid vessels are increasingly being designed and built. On such vessels, in order to completely reduce movement resistance and increase seaworthiness, combined hull contours are used, and they also use unconventional hydrodynamic principles of support - using hydrofoils or an air cushion.
Because of our awareness and compliance with strict federal, state and local regulations, we are proud to be the only ferry in the United States to participate in this program. All these standards must be kept up to date; as there is an annual renewal process that we must participate in to maintain this certification.
1. Catamarans with high aspect ratio hulls and V-shaped contours
The main component of the total resistance of a high-speed vessel is wave resistance, caused by the occurrence of ship waves under the influence of gravity of liquid particles. The wave formation caused by the movement of the vessel consists of bow and stern groups of divergent and transverse waves, and transverse waves play the main role in creating resistance. As the vessel moves, an overlap occurs - interference of these groups of waves. At certain speeds, unfavorable interference occurs, as a result of which the amplitude of the resulting waves increases and the wave resistance increases; at other speeds, on the contrary, favorable interference of the bow and stern groups of waves is observed, i.e. there is a decrease in the intensity of wave formation behind the stern and the overall value of wave resistance R in decreases.The pattern of wave formation behind the hull of a moving vessel, and therefore the value of R in, depends primarily on the speed of movement, therefore the wave resistance is modeled using the Froude number
We closely monitor how much non-recyclable waste is produced each year and have consistently reduced the amount over the years. We promote recycling of bottles, cans, paper and even our printers and toner cartridges. Fluorescent bulbs with green tips are a must.
The International Organization for Standardization is an international standard-setting body consisting of representatives of various national standards bodies. For example, in other countries where pronunciation varies, such as the International Warp Organization, the initials will result in different acronyms. It also reflects the goals of the organization; align and standardize different cultures.
At low speeds, determined by the Froude number 0.10÷0.15, wave resistance is practically absent. With increasing speed, it increases sharply and at Fr ~ 0.5 a clearly defined maximum R in is observed - the problem arises of overcoming the so-called “wave barrier” (for this it is necessary to use various hydromechanical and structural means).
Program partners provide leadership in many areas, including those that are not currently regulated, such as energy use, greenhouse gas emissions, and water consumption. It is not only conveniently located near the city center, but also directly on the Danube Canal.
Within a radius of about 300 m you will find, among other things: a supermarket, a cafeteria, a bakery, a pharmacy, two fast food restaurants, several banks, two ice cream parlors, an outdoor swimming pool, an indoor swimming pool, a gas station, a city bicycle station and a hospital.
Wave resistance also very significantly depends on the shape of the hull contours and the ratio of the main dimensions of the vessel. In this case, the predominant influence on R in is exerted by: coefficient of overall completeness of the vessel 5; relative hull length L/B or L/V 1/3 (where V is the volumetric displacement of the vessel); relative width of the H/T, as well as the contours of the vessel at the extremities. In this case, an increase in the relative length contributes to a decrease in R, the greater the higher the Froude number.
Many attractions are within walking distance. Relax with a cocktail at a beach bar on the Danube Canal, gaze at the stars at the Urania Star, or visit a bathing ship and float under Vienna's Nachtimmel. For all the night owls Bermuda Triangle with its countless pubs offers itself.
With this high-speed catamaran you will reach the Slovak capital Bratislava in 75 minutes. The Danube Canal also has its charm for sports lovers. You can walk right behind front door, ride a bike or skate. The Vienna City Marathon route leads directly past the apartment.
Wave resistance decreases intensively with increasing depth of immersion of the body (ship's hull). It is known that submarines in a submerged position do not experience wave resistance. The relative depth of immersion of the body, during movement at which there will be no wave formation, can be determined from the condition H/L ≥ 1.5·Fr-0.15.
There is a parking lot along the road. There are three garages nearby. We appreciate your comments for updates and expansions to this page. Our editorial department invests a lot of time in research to ensure the site's content is relevant, understandable and correct. However, it cannot be ruled out that the content of this page is not relevant.
You can help us: do you have any suggestions for updating or expanding the information on this site? Is there an important link to other sources of information? The catamaran climbs like a low-lying predatory bird with muscular wings. High above the water, sailors crouch on one of the yacht's hulls. They protected their heads with a helmet. No wonder: the maximum speed of a two-seater boat is about 80 kilometers per hour.
And finally, a hydromechanical interaction between the wave systems of both hulls occurs on a moving catamaran. If their interaction is favorable, a slight reduction in R in can be achieved, the magnitude of which also depends on the contours of the hulls and their horizontal transverse clearance.
In order to improve the propulsion and seaworthiness of catamaran hulls, they are usually made with a large relative aspect ratio l k / b k. In this regard, for example, a series of six vessels from the Australian company "InCat" should be noted. On the largest catamaran of this series, "InCat 050", built in 1998, the hulls have a very high relative aspect ratio - 19.1, which made it possible to significantly reduce wave drag at full speed and ensure an operating speed of 42 knots with a relatively moderate power plant power.
This summer, the world's most famous sailors will host the most famous regatta on earth. The venue is San Francisco Bay time, “a spectacular sailing amphitheater,” as Larry Ellison puts it. An extreme sports spectacle of the first quality is expected. First of all, however, the Cup will not be the first time a competition for shipbuilders. All seven racing teams are currently trying to capture the sails.
In the center there is 260 square meters, roof 40 meters high. Up to four times more efficient than a conventional sail should be a riser. Flaps on the trailing edge allow you to adjust the profile of the wing in wind conditions while driving. The wing, on the other hand, does not need a train, but retains its shape on its own. In a warehouse at San Francisco's Pier 80, Jordan and his colleagues are currently working on the intricacies of the American catamaran. Experts evaluate data from more than 150 sensors installed on board the ship.
An even larger catamaran with “ultra-narrow” hulls having an aspect ratio of 21.7 is currently under construction. With main dimensions of 120x29x4.7 m, the length of the hulls along the vertical line is 102.3 m, and the width is 4.7 m. With a deadweight of 1200 tons and a gas turbine power plant with a power of 4x13100 kW, the vessel will be able to reach a speed of 51 knots, having 1200 passengers and 460 cars on board.
They prevent the boat from drifting sideways. As a result, when the catamaran is fast enough, the catamaran rises completely out of the water. Suddenly both ships are floating in the air at the same time. Like a horse whose reins are loosened, the boat accelerates to almost twice its speed in a matter of seconds.
But the sword on the windward side and the two long rudders still cut the water, leaving a fine mist of sparkling spray. At such a moment, swing your sword up to 200 tons. The carbon fiber board is only about one meter wide and eight meters long. "It's a rope," Jordan says, "we're exploring the limits of stability." This also applies to the crew. Eleven weathered muscle packs are on board. They've been doing the job for 17 years, Skipper Spill says. In pairs they can be boiled on winches, for example to use the hydraulics of the swords or to close the front end which tows the four ton boat.
The Japanese company "IHI" has developed a standard range of catamarans with "ultra-thin" hulls of the "SSTH" type (Super Slender twin hull) with a length from 30 to 200 m. One of the largest catamarans in this series, having main dimensions of 153.5x27.5 m, will be capable of reach a speed of 37 knots with a two-shaft power plant with a total power of 41,200 kW.
It is known that when moving in rough seas, a ship experiences vertical, roll and longitudinal motion, which results in flooding of the deck and superstructures, the danger of slamming (i.e. hydrodynamic impacts of the hull on an oncoming wave) and loss of stability. All these phenomena significantly worsen the comfort of passengers and the habitability of the crew. The impact of waves causes accelerations (overloads), which are usually estimated as fractions of the acceleration of free fall g (if the magnitude of these overloads, measured at the center of gravity of the vessel, is below 0.2g, the seaworthiness of the vessel is assessed as sufficient).
Exit - installation of wings
"This time the America's Cup is really about sailing skill," says Anthony Spytil, "the average sailor wouldn't have a chance to get this boat adrift." Even Spillhill himself suffered a setback on the Supercatamaran. With a wind force of six, it tapped the water in front of the San Francisco waterfront last October. Suddenly the catamaran lost its balance. The bow of the giant yacht drifted into the stormy sea. The stern rushed upward. The catamaran took off.
In flight mode on small boats
They allow you to swim at high speeds just above the water. The trend sparked the America's Cup. This was new for Ernesto Bertarelli. At the end of the regatta, the crew had mastered wing handling better than their opponent from New Zealand. Therefore, it is clear that the sailors of the participating teams are already practicing “flying over the water” on various small films. The foil works like an airplane wing. If the speed is sufficient, it creates buoyancy so that the boat's hulls rise out of the water. This reduces resistance in the water and increases boat speed.
In addition, in rough conditions, the ship's performance deteriorates due to an increase in movement resistance and a decrease in the efficiency of the propulsors. In some cases, it becomes necessary to deliberately reduce the speed of the vessel or even change its course.
One of the constructive means of increasing the seaworthiness of catamarans is the use of “deep V” type contours, which until recently were widely used only in boat building. Compared to conventional low-left and round-chine, V-shaped contours, which soften impacts on waves, can significantly reduce the likelihood of slamming and increase the vessel's stability on course; In addition, its flooding with water decreases and stability increases. An important operational advantage of V-shaped contours is the reduction in the actual loss of speed when sailing in rough seas.
In order to further improve operational efficiency, most high-speed catamarans built recently are equipped with a special system for stabilizing the vessel's motion in rough conditions (MDS (Motion Damping System). This system includes T-shaped hydrofoils with flaps installed in the bow end of each hull, active trim tabs on the transom - controlled transom plates, as well as spoilers along the perimeter of the hulls. As experience has shown, the MDS system provides moderation (by 50%) of the amplitudes of pitching and movements during vertical pitching; reduction of overloads by 1.5-2 times, as well as simplification of trim in rough conditions. As a result, the level of comfort on board is significantly increased.
In particular, such a system was used on a passenger catamaran with sharp-chine lines, built at the Ukrainian shipyard "More" (Feodosia). The catamaran with a displacement of 77 tons has smooth dimensions of 30.4x8.6x0.9 m and a capacity of 200 passengers. The two nose T-wings are made of titanium alloy. Interceptors are installed in the stern. The 4x788 kW diesel propulsion unit operates on two propellers, providing a speed of 45 knots.
2. Catamarans with a relatively small waterline area
As noted above, a reduction in wave resistance can also be achieved by deepening the floating volume of the vessel, i.e. creating a catamaran with subsurface hulls of the SWATH type (SMPV). This modification has also been developing recently. Structurally, the SMPV consists of two underwater cigar-shaped hulls with a large relative elongation, each of which is connected to the surface part of the vessel, which looks like a load-bearing platform, using one or two vertical posts. This platform houses the transported cargo, premises for passengers, and equipment. The underwater hulls house the power plant, ship systems and devices, ballast and fuel tanks.A characteristic feature of SMPV catamarans is the small area of the active waterline - it is determined only by the cross-sectional area and the water level of the supporting struts. Their main operational advantages are high seaworthiness and comfort, reduced speed loss in rough seas. These positive qualities are due to the low disturbing effect of waves on the ship (due to the reduced waterline area) and the large values of the natural periods of vertical and pitching, as a result of which the ship is less susceptible to slamming and flooding. However, SMPVs have a larger specific wetted surface area of their hulls compared to conventional catamarans, and this leads to an increase in friction resistance. In terms of energy characteristics, such vessels can be competitive with other multihulls only at sufficiently high speeds at which wave drag becomes the main component of total drag. For catamarans of the SMPV type, a reduction in wave resistance is achieved by deepening the hulls and using favorable interference - the superposition of wave systems.
Recently, double-hulled vessels with partial use of the SMPV concept have been designed and built as hybrid catamarans. Such vessels are called “semiSWATH”. Structurally, they are made with a reduced hull width in the area of the operational waterline. A number of fairly large catamarans have been designed and built using this principle in Norway, Denmark and Australia.
Of significant interest are the hybrid catamarans "HSS.1500" and similar, but smaller in size, type "HSS.900". The complex of structural and hydromechanical means used on these vessels resulted in a significant reduction in wave resistance at the design speed (40 kts) and an increase in performance. We note the unusual shape of the hull contours with a large relative elongation, the reduced (compared to conventional catamarans) area of the active waterline, the use of bow bulbs, as well as the installation of active roll dampers and bow thrusters on both hulls. The maneuverability of catamarans has been improved, and the level of vibrations and overloads caused by waves, as well as noise in passenger cabins, has been structurally reduced.
As an analysis of the tests of the lead catamaran "Stena Explorer" (type "HSS.1500") has shown, its Froude number is 0.58 (for vessels of the "HSS.900" type it is even higher and equal to 0.7). Thus, we can conclude that the design operating mode of these vessels, thanks to the use of a number of new solutions, falls in the region that is supercritical in terms of wave resistance (i.e., higher than Fr ~ 0.5). This is also facilitated by the increased power supply of the vessel (the total power of the main power plant is 68,000 kW) and the high efficiency of the multi-shaft water-jet propulsion system.
The Danish catamarans "Mai Mols" and "Mie Mols" of the "Seajet-250" type, which use the same semi-SMPV concept, are successfully operating. These ferry-type vessels have the following main characteristics: main dimensions - 76.12x23.4x3.36 m; deadweight - 250 tons; capacity - 450 passengers and 120 cars. A two-shaft gas turbine power plant with a total power of 24,800 kW, which drives four KaMeVa water jets, provides an operating speed of 43.6 knots and a maximum speed of 46.4 knots.
Welded construction housings are made of aluminum. In the area of the operational waterline they are partially narrowed, which led to a slight decrease in the areas of the waterlines. The hulls are designed with high aspect ratio and a bulbous bow, which also helps reduce wave drag at design speed. It is noted that the applied solutions resulted in a 50% reduction in vertical and longitudinal movements and overloads during operation in rough seas. Thanks to the additional buoyancy of the connecting bridge and the division of the hulls into waterproof compartments, the ship's unsinkability and emergency stability are ensured when both hulls are flooded by 1/3 of their length.
Additional resistance when sailing in rough seas does not exceed 4-6%; vessels maintain their design speed when operating on waves up to 2.5 m high.
The semi-SMPV concept is also used on several Auto Express 82 catamarans built in Australia. These are the ferry ships "Felix" and "Dolphin", having main dimensions - 82.3x23.0x2.7 m; deadweight - 320 t; capacity - 676 passengers and 156 cars; a four-shaft water jet system of the "KaMeVa 112" type, driven by four diesel engines with a total power of 24,000 kW, provides an operating speed of 40.5 knots and a maximum speed of 41.5 knots.
3. Catamarans with unconventional maintenance principles
The majority of catamarans built and currently being designed are displacement-type vessels, the buoyancy of which is ensured by hydrostatic (Archimedean) support force. It is known that as the speed of movement increases, the magnitude of this force decreases, since hydrodynamic support forces arise and begin to play an increasingly important role. There are various means of practically implementing the hydrodynamic principle of maintenance. For this purpose, planing or semi-planing hull contours are used, and recently, load-bearing hydrofoils have been used, which make it possible to lift (or lift) the hull out of the water and thereby reduce the resistance to movement. Lifting a vessel from the water can also be carried out using aerostatic forces created by an air cushion.Hydrofoil catamarans
The wing device necessary for the movement of the vessel in the foil mode must ensure the rapid release of the vessel onto the wings, its stable and safe movement not only in calm water, but also in rough water (at a given wave height), and maintain a constant lifting force of the wings in a wide range of speeds progress. Of course, it must be simple and reliable to use.Most of the built sea catamarans-SPK use deep-submerged, automatically controlled hydrofoils (AUK). The constant lift force of these wings is ensured by changing the angle of attack of the mechanical flaps by turning them using an automatic system. As operating experience has shown, AUPK not only provide an increase in speed, but also can significantly reduce the harmful effects of pitching and increase comfort.
Some PDAs have swept-back wings. Giving the wing a sweep delays the appearance of cavitation (it occurs at higher speeds), increases the ship's course stability and its seaworthiness. The speed corresponding to the moment the hull lifts off the water for most SPK catamarans is within 0.5÷0.6 of the full speed.
The Norwegian company "Westmarin West AS" has built a high-speed CPC "Foilcat 2900", the wing structure of which consists of split bow and stern solid (uncut) wings made of stainless steel. The span of each bow wing is 2.5 m, and the stern one is 7.79 m. Both wings are flat and deeply submerged, and have a swept plan. The stern wing carries 60% of the ship's mass, and the rest of the load falls on the bow wings. Two pulling propellers with a diameter of 1.25 m are used as propulsors, power transmission to which from diesel engines is carried out through an angular gear.
Of great interest is the high-speed SEC "Rainbow", built in Japan by MNU. It uses a number of new technical solutions to ensure a comprehensive reduction in displacement, increasing the hydrodynamic efficiency of the wing structure and water-jet propulsors. A special feature of the hulls is the use of V-shaped contours over a significant part of their length, which helps to increase the seaworthiness of the vessel. The housings are made of aluminum, and the design includes additional elements to reduce vibration and noise levels in passenger compartments (up to 76 dB).
The wing device consists of two stainless steel AUPCs, identical in all characteristics. The span of each wing is 12.8 m. The end sections of the wings are solid, and the rest is hollow. To ensure stability of movement, a special wing control system APF (Auto Pilot on Foils) is installed.
The propulsion system consists of four high-speed lightweight diesel engines of the S16R-MTK-S brand, which have increased performance characteristics, and two MWJ-5000A water jets, developed by Mitsubishi. The blade mechanism of this water jet, unusual in type and design, having a cascade-type impeller with two rows of blades, is capable of developing additional thrust to overcome the “hump” of resistance when reaching the wings. Controllability and maneuverability are ensured by the reversible steering device of the water jets, as well as by a system of flaps installed on the nose wing struts.
Another Japanese company "Hitachi Zosen", continuing work on the creation of new and increasingly advanced catamarans, built the lead SPK of the "Superjet-40" type with a displacement of 300 tons and a speed of 45 knots. This is a further development of the previously built series of “Superjet-30” type ferries: dimensions and passenger capacity have been increased (up to 300 people); the use of a more powerful power plant made it possible to increase the speed by 7 knots. Two AUPK are located between buildings with V-shaped contours. Four diesel engines (two per hull) power two water jets. An increased level of comfort, good seaworthiness and maneuverability of the quality control department are noted.
The design and construction of double-hull SPCs are also carried out in South Korea. Thus, back in 1993, the company "Huindai Heavy Ind" built the first PDA, which had the main dimensions - 45.0x11.4x1.6 m and a passenger capacity of 300 people. The wing device consists of two AUPK. A two-shaft diesel power plant with a total power of 8210 kW provides an operating speed of 40 knots. Based on the successful operating experience of this catamaran, a design for a larger OTK with a length of 80 m (deadweight 240 tons), designed to carry 630 passengers and 160 cars, was developed. Four gas turbines with a total power of 28,000 kW, driven by two water jets, provide a speed of 45 knots.
Let us note that the displacement of OTKs already in operation, as a rule, does not exceed 300 tons. The creation of larger catamarans on wings, as experts note, is problematic, since the dimensions and weight of the wing device increase significantly; In addition, there are design difficulties in implementing automation of wings of such large sizes. That is why, when it comes to larger catamarans, hydrofoils today are not considered as a means of increasing speed, but only as the main part of the system for stabilizing the motion and trim of the vessel (see above about the MDS system).
Hovercraft catamarans
Two fundamentally different types of hovercraft are known: amphibious, the hull of which can be completely detached from the water when moving, so that the vessel is able to go ashore, and non-amphibious, or skeg-based, with the hull not completely detached from the water, having rigid side railings (skegs) air cushion zones.The first small-sized skeg hovercraft were built in the 60s, including in our country; their speed was 30-40 knots. The experience of creating and operating these skeg-mounted hovercrafts has recently been used to develop designs and build ever larger hovercraft catamarans (hovercraft).
Each hull of such a hovercraft consists of a main part and skegs extending from it down the sides - narrow hulls, the width of which is usually less than half the width of the main part. On small-tonnage hovercraft, “narrow skegs” are used, and on medium-tonnage and large vessels, skegs are made in the form of volumetric displacement structures.
These skeg-hulls not only enclose the airspace area, but also provide the buoyancy and stability of the catamaran, its general and local strength; serve as a volume to accommodate engines and propulsors.
On hovercraft bodies in a static position, a hydrostatic (Archimedean) support force arises
(where W sk is the immersed volume of one skeg), and during movement a certain hydrodynamic lift force also arises.
A distinctive feature of the hovercraft is the presence of a special lifting complex designed to create and maintain the hovercraft under the bottom of the main part of the hulls. The resultant of the static air pressure on the bottom of the body is the aerostatic lift force of the hovercraft, which is determined by the expression
(where P VP - air pressure in the pillow; S VP - pillow area). Thus, the total supporting force of the catamaran will be equal to
On constructed hovercrafts, 80-85% of the total force supporting Y falls on Y ac and 15-20% on Y gs. An important structural element of double-hull SPCs is the flexible enclosure of the air cushion area at the extremities. It must be sufficiently flexible and have a special shape that provides the least hydrodynamic resistance.
The above-mentioned features of the hydro-aerodynamic configuration of the hovercraft necessitate a separate power plant for creating and maintaining an air cushion; on built and designed catamarans, its power is 25-30% of the total power of the vessel's power plant.
High-speed light diesel engines and gas turbines in various combinations are used as the main engines on the hovercraft; propellers of various types (including CV propellers, CPV and supercavitating propellers, designed for operation in conditions of highly developed cavitation) and water jets are used as propulsors. Characteristic is the widespread use of multi-shaft water-jet installations with increased energy characteristics. This is due to such advantages of water jets as compared to propellers, such as ease of arrangement in narrow skegs (hulls), structural simplicity and increased operational reliability, the ability to reduce the vessel's draft, reduced noise and vibration levels of the hull, and high maneuverability of the water jet vessel.
Analysis of operating experience indicates the prospects for further development of hybrid hovercraft catamarans, providing an increased level of comfort. There is a low exposure of the vessel to the influence of wind and sufficient stability on course, relatively low overloads from the impact of sea waves on the vessel, and the absence of high-frequency noise, which is created by air propellers on amphibious hovercraft.
The largest catamaran of this type is the technosuperliner TSL-A "Hisho", developed under the Japanese program for creating high-speed RO-RO ferries. This ferry has main dimensions 125x27x4.7/1.5 m (draft of 1.5 m corresponds to hovercraft mode); payload 1100 tons. The propulsion power plant, consisting of two gas turbines of the LM 1600 type with a total power of 26,200 kW, operates on four water jets, providing a speed of 42-50 knots. A diesel power plant consisting of four 4410 kW engines drives fans to create and maintain air power.