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AO 177 Cimarron

Fleet oilers operate as a unit of an underway replenishment group, replenishing petroleum products and ordnance to the fleet at sea during underway replenishments (UNREPS). The oilers transport bulk petroleum and lubricants from depots to the ships of the battle group. The ships also transport and deliver limited Fleet Freight, mail and personnel to combatants and support units underway. The ships are simultaneously capable of providing three double-probe fuel rigs to port, and two single-probe fuel rigs to starboard, delivering a maximum of 900,000 gallons-per-hour of diesel fuel marine.

The CIMARRON class can be recognized by their merchant-like profile with the superstructure located aft. This class primarily delivers fuel to underway units. The AO(J)-177 class was designed to provide two complete refuelings to a carrier task group. All five ships of the class have been "jumboized" to increase capacity from 120,000 to 180,000 barrels of petroleum and to add ammunition (300 tons) capability. These ships can carry limited amounts of dry and refrigerated stores in containers on deck. These ships are equipped with a flight deck capable of operating any Navy helo, but have no hangar facility or embarkation capability.

The AO 177 (Jumbo) Class Fleet Oilers are programmed to satisfy the requirements for shuttle ships operating in support of Fleet units. The objective of the AO 177 Class jumboization program is to acquire (through the jumboization of five (5) existing AO 177 Class ships) replenishment shuttle ships capable of the rapid transfer of petroleum, oil and lubricants (POL) to battle group replenishment ships by means of vertical and connected replenishment (VERTREP and CONREP) at sea. In the absence of a battle group station ship, the AO 177 (Jumbo) will be capable of operation with the battle group as an attrition filler. The AO 177 (Jumbo) Class ships will incorporate additional mission critical capabilities such as expanded cargo fuel capacity, new dry cargo underway replenishment rigs, additional berthing, and cargo van tiedowns. 1987 Congressional budget action mandated that the Navy Jumbolze the 177 Class to a 180,000 barrel oil only variant, and authorized $40.OM for the lead ship jumboization.

The AO 177 (Jumbo) design incorporates the addition of a 108' parallel mid-body, providing for increased POL capacity (from 120,000 barrels to 180,000 barrels). The AO 177 (Jumbo) Class ships were jumboized from existing AO 177 Class ships; therefore, systems, subsystems, components, etc., that had been installed and proven operationally suitable on the AO 177 Class Fleet Oilers were utilized to the maximum extent practicable. New systems/equipment to be installed on the AO 177 (Jumbo) Class ships included standard tensioned replenishment alongside method (STREAM) underway replenishment (UNREP) equipment designed and instal led to Navy standards. Construction techniques used in the jumboization process (i.e., construction of the mid-bodies) were similar to the original AO 177 Class ships standards.

A major shipboard noise source comes from the ship's propeller excitation of the ship structure. The excited structure then re-radiates as airborne noise.The AO-177, first of a new class of Naval Auxiliary Oilers, experienced high levels of inboard airborne noise and initial-stage erosion damage on its skewed, seven-bladed propeller during builder's trails. To evaluate the problem, extensive model experiments were conducted, including flow visualization, wake survey, powering experiments, and a crucial series of cavitation experiments including propeller-induced hull pressure measurements in a large water tunnel. Experiments with two fin designs showed the superiority of a flow-accelerating configuration. Other experiments showed some benefits of altering the propeller blade shape. Propeller analyses were undertaken to provide design alternatives for retrofitting the ship with a new propeller. A full-scale trail with the final fin design provided evidence or reduction of the highest levels of airborne noise, reduction in the initial-stage erosion damage, and minimal effect on ship speed. The result is that the AO-177 was accepted by the fleet for normal service, with AO-177 commissioning 10 January 1981.

The number of Navy-manned fleet oilers has decreased as more and more Military Sealift Command ships, manned by a civilian crew and commanded by a civilian master, have assumed responsibilities for supplying deployed ships.

The ship's fully automated two-boiler steam propulsion plant propel them at sustained speed of 20 knots while carrying a load of 150,000 barrels of fuel and 625 tons of ordnance. Liquid cargo transfer is provided by STREAM (Standard Tensioned Replenishment Alongside Method) double-hose stations located on the port and starboard sides. For receiving fuel, there are double receivers on the port and starboard sides. Fuel delivery is controlled by the Ship's Automated Liquid Cargo Control System. There is one replenishment station located on each side to provide the capability to transfer cargo, Fleet freight and personnel. Both replenishment stations have a cargo boom for ship-to-shore transfer of supplies while the ship is in port. In addition, the ship has a flight deck aft for receiving and sending freight and passengers by helicopter.

The primary mission of USS Merrimack (AO 179) - underway replenishment (UNREP) - required a large number of deck seamen. As a result, this fleet oiler was manned with many non-designated seamen straight from boot camp and apprenticeship training. Recruiters talk about "striker boards" and the wide variety of options available at a Sailor's first duty station. On Merrimack, those options came to life. The Chief Petty Officer (CPO) Mess worked together on board Merrimack to make those promises a reality for their Sailors. In the deck department, seamen were put to work learning some of the most complex operations in the boatswain's mate rating. Every non-designated seaman striker spent about a year in deck department, learning basic seamanship skills and the UNREP trade as a member of a rig team. The strikers also helped maintain not just one, but two full length weatherdecks. This year was also an opportunity to complete basic shipboard requirements such as damage control, 3-M and quality assurance, to make at least one paygrade jump and to look around at the different ratings the Navy offers. Merrimack encouraged Sailors to explore the 25 different ratings available on board, as well as other ratings available in the Navy. Merrimack's ever changing schedule and round-the-clock UNREP availability demanded the crew be flexible. The requirements of a high operational tempo left most Sailors on board little time or energy to pursue extra activities. Non-designated personnel were even more taxed, striving to find a trade that fits.

WILLAMETTE is the first ship of the class to be protected by two MK 15 Phalanx Weapon Systems. Extensive damage control equipment and systems ensure rapid response to control any type of emergency. On September 27, 1991, WILLAMETTE was the second ship of the CIMARRON class to complete jumboization. A 108 foot midbody section was added to the center of the ship. This midbody increased fuel capacity by 30,000 barrels and added an ordnance cargo capability of 625 tons. The midbody also features an additional emergency diesel generator and two standard tensioned replenishment alongside method (STREAM) cargo stations. Ballast and cargo transfer systems are fully automated and designed to effect safe and efficient transfer of bulk petroleum cargo. Habitability has been improved over previous designs, and labor-saving devices have been incorporated to promote a reduced manning plan.

Fleet oilers are designed to carry and transfer petroleum products to other ships at sea, primarily to multiproduct ships. These multiproduct ships, in turn, refuel combatants and other ships. However, by the 1970s many of the oilers were victims of the same malady suffered by the Navy's auxiliary fleet -- age, and consequently they were retired from the active fleet. The Navy, to fill the void that resulted from the retirement of the aging fleet oilers, procured five new fleet oilers at an estimated cost of $664.4 million. Three of the oilers were under construction by 1977, and two more were authorized in fiscal year 1978. The oilers approved in fiscal year 1978 l cost an estimated $322.7 million. The first oiler obtained under this program was scheduled for delivery in fiscal year 1980, with follow-on deliveries through fiscal year 1981. As the new oilers entered the fleet, older ones were retired and others were assigned to the Military Sealift Command. All new oilers were initially crewed with Navy personnel.

The design of this oiler is aimed at optimizing manning and reducing costs while providing a ship that will be able to meet requirements. To accomplish this objective (1) commercial specifications were used where feasible and economical, (2) manning was reduced, (3) more automated systems and equipment were employed, and (4) existing subsystems, components, and equipment were used wherever practicable.

Fueling at sea capability is provided through three double hose stations on the port side and two single hose stations on the starboard side. The new oilers have the capability to transfer 900,000 gallons of marine diesel fuel and 540,000 gallons of aviation fuel per hour from both sides at the same time. Receiving capability includes three double-probe receivers on the starboard side and three single probe receivers on the port side. Delivery and receiving stations will use 7-inch hose outlets for both marine and aviation fuel.

Other features of the oiler include a pickup and drop area for replenishment by helicopter and limited capability to transfer and receive other cargo, mail, and personnel. A standard Navy communication system and limited self-defense in the form of two close-in weapons systems will be included on the oilers.



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