Powhatan class
| Powhatan class | |
|---|---|
_port_bow_view.jpg) USNS Powhatan (T-ATF 166), lead ship of the class |
|
| Overview | |
| Type | Deep sea tug |
| units | 7 built, 4 in service |
| Namesake | Powhatan |
| 1. Period of service |
|
| period of service |
since 1980 |
| Technical specifications | |
| displacement |
2260 tn.l. |
| length |
73.2 meters |
| width |
12.8 meters |
| Draft |
4.57 meters |
| crew |
16 civilians, 4 naval operators |
| drive |
2 GM EMD 20-645F7B diesel engines, 2 adjusting screws, 7790 HP |
| speed |
14.5 knots |
| Range |
10,000 nautical miles |
The Powhatan-class is a class of heavy ocean tugs operated by the United States Navy . The ships have been in service with the US Navy as ocean tugs and salvage ships since 1979.
history
Development and construction
The tugs were developed from July 1974 after a study by the Center for Naval Analyzes as a replacement for the deep- sea tugs of the Navajo and Abnaki class , which came from the Second World War . They should also be able to be used as multifunctional rescue and recovery ships. As a basis for the design of the ship, the developers took civil offshore supply tugs like those used on oil rigs . This design was intended to reduce the operating costs of the ships, but it was adapted to military requirements in order to increase their usability. The construction contract for the first five units was placed on September 12, 1975 at Marinette Marine Shipyard (now Lockheed Martin ) in Marinette , Wisconsin . The first ship, the Powhatan , was laid down on September 30, 1976. It was launched on June 24, 1978 and entered service with the US Navy Military Sealift Command on June 15, 1979 . The second construction lot of five ships was ordered on February 27, 1978, but two ships were canceled again. The last ship, the Apache , was handed over to the Navy on July 23, 1981 after two years of construction. The construction costs per ship amounted to about 17 million US dollars, the entire program was worth about 108 million dollars, in addition there were about 650,000 dollars in equipment costs per ship.
designation
The ships are named after famous Indian tribes from the United States. The type ship and with it the class was named after the Indian Federation of Powhatan from Virginia .
Present and Future
Four of the ships were stationed on the east coast of the USA, three on the west coast. The two oldest ships in the class were retired in 1999, and the Mohawk was also decommissioned in 2005 . The remaining four ships will remain in service with the Military Sealift Command for some time.
technology
_entering_Yokosuka_port.jpg)
Hull and superstructure
The body of the Powhatans is 73.2 meters long and 12.8 meters wide. The draft is 4.57 meters, the displacement when loaded is 2260 tn.l. , the displacement is 1367 tn.l.
Characteristic of the ships is their flat aft deck, which is only about one meter above the waterline and takes up the rear half of the hull length. In front of it are the superstructures of the ship with the navigation bridge and the crew quarters as well as the two chimneys lying next to each other. The bow is pulled up very far and there are three anchors of the ship on it.
The two masts for the navigation radar and the radio systems are located above the bridge and between the chimneys.
drive
The ships are propelled by two General Motors EMD 20-645F7B diesel engines with 3895 hp each . These drive two controllable pitch propellers in Kort nozzles , which accelerate the tug up to 14.5 knots (approx. 26 km / h) and allow a bollard pull of 54 tons. For maneuvering, the Powhatans have a bow thruster with an output of 304 hp. The fuel supply is 600 tons, the range is 10,000 nautical miles .
_port_rear_view.jpg)
Equipment and crew
The towing equipment of the Powhatans is on the quarterdeck, here are several strong winches and bollards for towing other ships. The flat deck has heavy mounting bolts at 60 cm intervals to which containers and other equipment can be attached. The deck can also be used as a helipad.
Behind the chimneys on the starboard side there is a crane with a lifting capacity of 10 tons, on the port side there is a seaworthy dinghy hanging in the davits . To provide support in the event of a ship fire, there are two high-pressure pumps on board, which feed three fire-fighting monitors on the superstructure. The monitors can generate over 8000 liters of extinguishing foam per minute . In addition to the extinguishing systems, there are also powerful searchlights on board.
In addition to the permanently installed systems, various modular rescue and rescue equipment can be accommodated on board, as well as diving equipment for rescue divers and material to contain environmental damage such as oil spills. Mobile diving robots can also be used on board.
The crew consists of 16 civilian seamen from the Military Sealift Command, who are supported by four communications engineers from the US Navy. During rescue operations, up to 20 rescue and recovery specialists can be accommodated on board.
Towing equipment on the aft deck of the Mohawk
Deployment of a submersible drone from the Narragansett
Diving on board the Navajo
_towing_equipment.jpg)
_deploys_Deep_Drone_RSV.jpg)
_diving_training.jpg)
commitment
_tows_USS_Missouri_(BB-63).jpg)
The tugs were and are used to salvage damaged ships or to tow decommissioned or damaged ships that can no longer drive on their own. The transport of non-motorized pontoons or barges is also their job. During fleet maneuvers they serve as a safety device and are used as target tugs for exercises with sharp weapons. Fighting oil spills and other environmental disasters is also part of their area of responsibility, as is the use of divers to rescue ships. The ships are also used in search and rescue missions.
Two of the active ships are in service with the Atlantic fleet, two are stationed in the Pacific. They are not assigned to fixed associations, but are deployed with the various US fleets as required. Annual operating costs are $ 3 million per ship.
Web links
- Powhatan class at globalsecurity.org (English)
Individual evidence
- ↑ a b globalsecurity.org , as of January 22, 2007
- ^ Terzibaschitsch: Sea power USA . Bechtermünz Verlag, Augsburg 1997, ISBN 3-86047-576-2 , p. 775
