Swath pilot transfer system
The SWATH pilot transfer system consists of the pilot station ship and the pilot transfer boats in SWATH ( Small Waterplane Area Twin Hull ) design known as tenders . A SWATH boat is a multi-hull boat similar to a catamaran that rolls significantly less than a monohull boat even in heavy seas. This minimizes the risk of the pilot translating .
The SWATH principle
SWATH ships have a double hull (similar to a catamaran ) with two torpedo-shaped buoyancy bodies under water, which are connected to the surface part of the ship by a narrow web-like construction. It is crucial that the areas that the water penetrates are as small as possible. The smaller these areas are, the lower the rolling movements in rough seas. This principle was first proposed in 1880 by the inventor Charles G. Lundborg.
In 1938 the Canadian engineer Frederick George Creed presented the idea of the SWATH to the British Navy and later also to the US Navy; however, they were not interested. In 1946 he was granted a British patent for it. The advantages were recognized at the time and should be used for Seadrome , a floating airport, among other things . The SWATH principle was subsequently patented for several applications. However, SWATH ships were only built and used by the shipping world for special applications, as their principle means that they only allow a small payload. Therefore, there remain applications for passenger transport, research and naval vessels. So the SWATH principle was z. It is used, for example, on the diving support ship Duplus (delivered in 1969 by Boele's Scheepswerf & Machinefabriek NV in Bolnes, Netherlands) for the oil industry. The SWATH ship Sea Shadow (IX-529) (US Navy and Lockheed 1985) and the research ship Frederick G. Creed (delivered in 1988 by the Swath Ocean Systems Incorporated shipyard, San Diego, California) also became known. Around 100 ships worldwide had been delivered according to the SWATH principle by 2011. At the end of 2012, the Abeking & Rasmussen shipyard, with 21 ships delivered, was one of the shipyards with the highest number of SWATH ships delivered.
Design and model tests of the SWATH pilot transfer system
Since there was little experience in shaping the underwater floating bodies and determining the ship's resistance, the design of the ships and the calculation of the propulsion power were carried out with the support of Prof. Dr. LH Seidl carried out. His calculations on the behavior in sea conditions at different speeds were particularly important .
Since the areas of this type of ship that are wetted by the water are larger than that of comparable monohull ships due to the underwater floating bodies, greater frictional resistance was to be expected. On the other hand, the particular advantage lies in the small waterline areas that pierce the water surface, which results in a very low wave resistance. The ship resistance, which is decisive for the propulsion power, results from the addition of the friction and wave resistance.
The ships were designed based on these theoretical results, models were built for the SWATH vehicles and examined in extensive test series in shipbuilding research institutes . In addition to the numerical CFD calculations (CFD = Computational Fluid Dynamics), these model tests were used to determine the ship's resistance and propulsion power as well as the wave patterns in the area of the supports. For this purpose, the research institutes had to develop new processes, as the small waterline areas, a special feature of this type of ship, did not allow freely diving and trimming models.
Test drives of the tender
The results of the test drives in the German Bight showed good agreement between the power requirement for the drive and the calculations and model tests. The typical resistance hump in the range of 9-11 knots calculated for SWATH ships and measured in the model test was also confirmed during the test voyage. As part of the development of the SWATH pilot system, a research project was carried out and therefore extensive test and acceptance drives were made possible, in which the Navy was also involved. For comparison, many trips were carried out together with a monohull ship. A patrol boat with a length of 50 meters and a displacement of 370 tons was chosen for this purpose. The behavior in sea conditions and the investigation of slamming effects were of particular interest. Slamming did not occur and the accelerations in the bow area were almost independent of the speed. The maneuvering tests showed that the ships are stable on course when sailing through the water and that the turning circle at full speed corresponds to about three ship lengths.
Application of the SWATH pilot transfer system for the Elbe Range concept
The concept, known as the Elbe Range, was planned and implemented for two 25-meter transfer boats called pilot tenders and for a 50-meter station ship for the Elbe estuary. This development work was carried out by the Abeking & Rasmussen shipyard by Dr.-Ing. K. Spethmann, and valuable experience was gained together with the pilots. The principle was largely adopted by the other pilot transfer services of the Weser and also for the Netherlands and Belgium. During the development and design work, the shipyard was commissioned by Prof. Dr. LH Seidl from the University of Hawaii , who had experience in designing SWATH ships.
SWATH station ship Elbe and SWATH tender Döse and Duhnen (1999/2000)
The system has been in use since the turn of the millennium with several SWATH pilot station ships and SWATH tenders. In 1999 the first pilot tenders Döse and Duhnen based on the SWATH design were put into service. The new SWATH station ship Elbe began its service in 2000. The tenders are manned and supplied from the station ship. The station ship returns to the port of operation at regular intervals, is supplied with fuel, water and supplies, and there is a change of crew and pilot.
Pilot station ship Elbe (Hanse)
The first Elbe to be built using SWATH construction was mainly located at its station in the sea area between Helgoland and Neuwerk. Due to the SWATH shape, the pilot's stay is more pleasant than on a monohull construction, even in heavy seas. Since there is much more space available in the significantly larger underwater floats, the engine rooms are located below. The cabins for the pilots and crew as well as the common rooms are located in and above the platform area.
In contrast to the pilot tenders, the station ship essentially fulfills tasks as a hotel ship and offers plenty of space for around 40 pilots and 25 crew members. With a length of 49.9 m, a width of 22.55 m and a draft of 6.5 m results in a displacement of around 1450 tons. The Elbe is measured with 2135 GT, has four diesel engines to drive four generators (4 × 750 kVA) and runs 14 knots with a drive power of 2000 kW.
In 2010 a new pilot station ship, which was 60.4 m long and 24.6 m wide, was delivered and it was also named Elbe . The old Elbe was renamed Hanse and is available as a replacement ship.
Pilot tender
The two pilot tenders Döse and Duhnen were designed as displacers with a displacement of 125 tons at a length of 25 m and width of 13.5 m for a speed of 18.5 knots (max. 20 knots). The main material used was aluminum alloys to save weight . The tenders are designed with a diesel-electric drive based on the "electric shaft" principle. The diesel generators are located in the engine room on the platform in front of the wheelhouse about 2 meters above the water level. The electric drive motors (2 × 800 kW ) are arranged in the underwater floating bodies and a spade rudder operated by a rotary vane is arranged behind each propeller . The total power to drive is 1600 kW. The superstructure was designed to accommodate at least eight pilots and two to three crew members. The wheelhouse is designed as an all-round viewing bridge with large windows and is equipped with two control stands, one on the starboard and one on the port side.
A lot of development work went into shaping the underwater floating bodies, the connecting supports and minimizing the waterline areas. Appropriate compromises had to be found here, since the supports had to be used not only to provide access to the traction motors, but also to route cables and ventilation. To improve sea behavior, active fins were retrofitted to the underwater floats.
The special shape of the pilot tender allows the pilot to climb up to 3.5 meters wave height at a speed of 8–12 knots (monohull 6–8 knots). A pilot lift is provided for climbing over (boarding), which can also be operated as "man over board" equipment. The ship's movements of the tenders are harmonized with four gyro-controlled fins at the ends of the ship, which are activated from a ship speed of 4 knots.
Pilot station ship Weser and pilot tender in SWATH design (2007)
The Wangeroog pilot tender in SWATH design has been in use for the pilot brotherhood since 2007 . The new pilot station ship Weser began service in 2010 and replaced the pilot station ships Gotthilf Hagen and Kapitän König . The Weser is 60 meters long and 24 meters wide and has chambers for a crew of 34 and 25 pilots. This means that the pilot station ship is deployed around the clock, depending on the duty cycle, for 14 to 21 days at its sea position around three nautical miles from Wangerooge.
SWATH pilot transfer system for the Netherlands and Belgium
In 2005 the Dutch sea pilots were equipped with two 25-meter SWATH pilot tenders ( Perseus and Cetus ). The Belgian pilots have also opted for this system. In December 2011 the third pilot tender was delivered and in 2012 the Belgian SWATH pilot transfer system was completed with the 60 meter long SWATH station ship.
SWASH - a further development
The Abeking & Rasmussen shipyard from Lemwerder provided a further development of SWATH technology with the Explorer pilot tender . The basic principle has also remained the same for the new development. In contrast to the existing pilot tenders, the ship only has a single torpedo-shaped float amidships. The side arms serve as supports for stabilizing floats. Hence the term SWASH as an abbreviation for Small Waterplane Area Single Hull . Machine systems including gearboxes are built into the underwater torpedo. This design meant that the pilot boat could be a little smaller. As a special feature, the pilot boat has a hybrid drive with diesel and electric motor.
See also
literature
- Karl B. Kühne and Günther Spelde (editors): The German sea pilot system . From the origins to the present day , Verlag HM Hauschild, Bremen 2006, ISBN 3-89757-256-7 .
- LH Seidl, WF Clifford, JP Cummings: Design and operational Experience of SWATH-Ship NAVATEK 1 . Marine Technology, Vol. 30, No. 3, pp. 153-171.
- K. Spethmann, M. Lühder, U. Kloschinski: SWATH ships for the pilot transfer system “Elbe Range” in the German Bight . Yearbook of the Shipbuilding Society 2000.
- K. Spethmann, W. Leue: New SWATH Generation of Pilot-System for the German North Sea Coast . International Symposium RINA SURV, Gothenburg 1997.
- Peter Andryszak: Two ways are better. In: Deutsche Seeschifffahrt , issue 11/2013, pp. 32–37, Association of German Shipowners eV, Hamburg 2013.
- K. Spethmann: An effective SWATH platform the size of a corvette . Eckernförde marine workshop 2009.
- Elbe range has become an export hit in Europe . In: Cuxhavener Nachrichten of August 29, 2007, accessed on December 17, 2012
Individual evidence
- ↑ a b baptism of the new "Elbe" , press release from Abeking & Rasmussen
- ↑ Swath technology in the North Sea ( Memento of the original from July 25, 2012 in the Internet Archive ) Info: The archive link was automatically inserted and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. , Elbe Pilot Brotherhood
- ↑ Versetzdienst on the Weser and Jade in the future , Lotsenbrüderschaft Weser II / Jade ( Memento of 26 February 2011 at the Internet Archive )
- ^ [1] , pilot boat with electric drive
Web links
- Piloting on the Elbe
- Technical data Elbe (PDF; 641 kB)