Multi-Purpose Field Support Vessel Delivered to Harvey Gulf for the Shell Stones Offshore Field – The RAmpage 6500-ZH Harvey Stone
November 9, 2016
The Harvey Stone is a Multi-Purpose Field Support Vessel (MPFSV) that will serve as a dedicated field support vessel for the Shell Stones FPSO offshore terminal. Her primary duties will be to operate as the dedicated pull-back tug, in support of, and assisting the berthing, loading and unberthing of offtake tankers of up to 46,287 SDWT. The vessel is expected to escort the above FPSO in the event of disconnection from the submerged buoy mooring for hurricane avoidance purposes and is also equipped to tow the FPSO in case of mechanical breakdown at any time during the transit way from or back to the field. Notable features include a hybrid propulsion system and a double-hull, which segregates all fuel, oil, and sewage from the hull as required by the specification and due to the fuel capacity.
The principal particulars of the Harvey Stone are:
- Length overall: 64.80 m
- Beam, moulded: 18.00 m
- Depth, moulded (hull): 7.80 m
- Maximum draft (DWL): 5.50 m
- Navigational draft: 6.40 m
Harvey Stone’s capabilities include:
- Evacuation assistance in accordance with the Gulf of Mexico Emergency Evacuation Plan (EEP)
- Carrying 120 survivors (in addition to the crew) in the event of an emergency
- Maintenance and inspection of the floating hose
- Transportation of stores and general cargo to the FPSO (including containerized stores and equipment, bulk stores, fuel and potable water)
- A cargo deck loading requirement that exceeds 5 tonnes/m2 (1,025 lbs/ft2) with a deck area of 250 m2 (2,690 ft2)
- FFV 2
- Ability to perform some anchor handling duties
To enable extended endurance at sea, the vessel has the following tank capacities:
- Fuel oil: 874 m3
- Fresh water: 192 m3
- Foam: 94 m3
- Ballast/drill water: 1,496 m3
Although normal operating crew is 15, the vessel is outfitted for a crew of up to 24 persons. The large main deckhouse contains a spacious galley/mess, cabins for senior officers, HVAC room, lockers, etc. The lower deck contains galley stores, cold storages, laundry room, engineer stores, workshop, etc. With forward and aft control stations, the wheelhouse has maximum all-round visibility particularly to both fore and aft deck working areas.
The deck machinery includes a single drum hawser winch at the bow, a water-fall double drum towing winch at the stern, stern roller, shark’s jaw-top pin unit, gobeye, deck crane, tow hook, tugger winches, capstans, storage reel, etc.
Ship-handling fenders at the bow comprises an upper course of 900 mm diameter cylindrical fenders and a lower course of 450 mm thick “W”-block Fenders. A 350 x 350 hollow “square” fender provide protection along the main deck sheer line and 450 mm thick “W” block type fendering is used at the stern.
The Harvey Stone is the largest of the Robert Allan Ltd. RAmpage series vessels built to date and the first to have the sponsoned hull form, similar to the RAstar escort series tugs. The vessel must perform in the following sea states:
- Winds up to 15 m/sec. (30 knots)
- Significant wave heights (Hs) up to 2.5 m (8.2 ft.)
- Current speeds up to 1.1 m/sec. (2 knots)
Pull back operations for the shuttle tanker:
- Winds up to 20 m/sec. (40 knots)
- Significant wave heights (Hs) up to 3.0 m (9.8 ft.)
- Current speeds up to 1.1 m/sec. (2 knots)
The vessel is fitted with a hybrid propulsion system that allows for economic propulsion (eco-transit (8–9 knots) and station keeping on one engine, driving mechanical/electrically to propulsion units and or bow thrusters. The hybrid system has a dual output (PTO/PTI)/single input gearbox driving the propulsion shaft line on one side and the motor/generator on the other. Since the vessel will see a large percentage of time at a loitering condition, while on station, it is more economical to utilize a single main engine to drive all propulsion units and house loads. The system is configured to operate a normal vessel with electrical power being generated with shaft alternators in conventional mode or DP mode.
The propulsion machinery comprises a pair of GE 12V250 MDC main engines with EPA Tier 4 emission certification; each rated 3,495 kW at 1,000 rpm and driving a Schottel SRP 3030CP azimuth thruster with a 3,400 mm CP propellers via a Reintjes LAF 3414 single input with dual outputs gearbox which will achieve at least 13 knots and 106 MT of Bollard Pull. Two Schottel STT 2 tunnel thruster with 610 kW of input power provide vessel DP-2 capability in conjunction with the azimuth thrusters. Ships electrical power generation and hybrid system is provided by Robichaux Automation and Control Inc., with primary propulsion load feed to VACON DC-Grid main propulsion switchboard and power generation coming from two Cummins QSK19 ship service generators each rated at 350 ekW, two Marelli Shaft Motor/Generator with 1,000 kW of power. Emergency electrical power is provided by a Cummins QSB7 generator with 120 ekW of power. This vessel design is one of the first applications of an EPA Tier 4 GE 12V250MDC main engine.
The vessel is fitted with a FFS provided off-ship firefighting system to Class FFV 2 system requirements, which calls for a significant amount more firefighting capacity than a standard FFV1 vessel.
Harvey Stone meets the ABS and USCG Rules as applicable for the following:
- ABS Rules for Building and Classing Offshore Support Vessels 2014
- USCG/ABS Supplement to ABS Rules for Building and Classing Offshore Support Vessels (ACP) 2014
- ABS, Oceans Service, ✠A1, ✠AMS, ✠ACCU, UWILD, ✠DPS-2, FFV-2, Ⓔ,OFFSHORE SUPPORT VESSEL, DSV CAPABLE, ROV CAPABLE, TOW, SUPPLY, HAB+(WB), ENVIRO, GP
Special attention was paid to the overall design in order to meet the HAB+ noise and vibration requirements, including vibration isolation of the main engines and silencers, and a specialized flooring system. To ensure the standards were met, Eastern Shipbuilding commissioned a separate noise study (including FEA model of the hull) by Noise Control Engineering.
This new RAmpage 6500-ZH class tug is the newest member of the very successful RAmpage series of offshore support tugs. The RAmpage series was developed by Robert Allan Ltd. to address a gap in the market for smaller high-performance towing and anchor-handling tugs for critical offshore terminal and oil-field duties. These RAmpage tugs are designed to be able to maintain station in extreme ocean conditions with enhanced manoeuvring and sea-keeping capabilities. For more information on the Harvey Stone or any other RAmpage series vessels, please contact us at firstname.lastname@example.org.