Eastern MPSV a platform for subsea specialization
Deep into the Gulf of Mexico oil field doldrums, there are still a few support vessel hulls moving module-by-module toward completion. Among the most notable are two subsea construction newbuilds at Eastern Shipbuilding Group in Panama City, Fla.
Harvey Sub-Sea, which was due for delivery in September, and sister vessel Harvey Blue-Sea, expected to deliver early next year, are 340-foot multipurpose support vessels (MPSVs) designed by Vard Marine. The Canadian company, formerly STX Marine/Aker Marine, is a subsidiary of the Italian company Fincantieri.
Harvey Sub-Sea is the first U.S.-flagged, Maritime Labor Convention-compliant vessel that meets the special purpose ship (SPS) classification, said Chad Verret, executive vice president of construction and LNG operations at Harvey Gulf.
“The key to the project was to come up with an understanding of the MLC requirements early on,” Verret said, which included accommodations. “For example, all of the crew quarters are required to have natural light. And they’re all singles and doubles. There are no four-bunk staterooms.”
Eastern project manager Ken Winpigler, left, confers with Chad Verret of Harvey Gulf atop the new vessel’s landing pad. A reception area adjacent to the deck has seating for 23 people.
The first challenge, according to William Lind, vice president of operations at Vard’s Houston office, was that Harvey Sub-Sea’s international reading of 8,000 gross tons exceeded the 6,000-gt threshold in the U.S. Coast Guard’s regulations for offshore supply vessels (Subchapter L). Vard, Harvey Gulf, the Coast Guard and the American Bureau of Shipping (ABS) developed a design basis letter listing all applicable regulations and certifications for the vessel to ensure “an adequate level of safety regarding fire protection, lifesaving, carriage of noxious liquid substances, helicopter landing facilities, dynamic positioning, carriage of more than 36 offshore workers, and probabilistic damage stability.”
Harvey Sub-Sea is one of the first vessels classed according to the new ABS offshore support vessel rules. Lind explained that the close relationship between Vard and ABS, and their close proximity in Houston, allowed for face-to-face meetings to resolve conflicts as they arose.
“Key drawings, such as the means of escape, were reviewed and approved early on in the process,” Lind said. “The collaborative approach led to quicker closeout of comments and a consequent reduction of risk through the build period, as well as the opportunity to jointly review and streamline the application of the new ABS rule set and OSV software.”
In June, Verret was at Eastern Shipbuilding’s Nelson Street yard in Panama City for meetings with Capts. Pat Hughes and Todd Dufrene, serving as Harvey Gulf’s on-site project managers, and Kenny Winpigler, Eastern’s project manager. Harvey Sub-Sea was a jumble of equipment, construction materials and tools as vendors and shipyard personnel worked toward completion and delivery.
Harvey Sub-Sea’s mast has generous separation between components to facilitate maintenance.
The massive vessel, which rises seven decks above the main deck, is capped by a Helidex Offshore helicopter landing pad. Dwarfing Sub-Sea’s bow, the 73-foot-diameter aluminum deck can accommodate helicopters the size and weight of a Sikorsky S-92.
Adjacent to the helideck is a reception area with seating for 24 people. “(It) makes for an efficient process for orienting and documenting personnel coming aboard and getting the helicopter away quicker,” Verret said.
On the 3,000-square-foot bridge, the draped consoles were cast in a bluish hue due to a plastic veil over the windows. However, the expanse of the space and the flood of light that soon would emanate from the generous sweep of windows were obvious. “There is even an eight-person conference table in the bridge wing,” Verret said.
Sub-Sea’s propulsion, aside from the Schottel z-drives and bow thrusters, is provided by Wartsila. It also provided turnkey installation of the fore and aft bridge control consoles, their integrated bridge, navigation and communication control system, and the complete electrical and automation system.
The vessel’s four Wartsila 6L32 diesel engines each provide 3,170 kW (4,251 hp), supplying power symmetrically to a 690-volt switchboard. A low-loss concept (LLC) system allows for the elimination of large transformers for power distribution, resulting in higher efficiency, lower weight and volume, and a high degree of redundancy.
There are a pair of ROV launch doors (the vertical opening) and embarkation stations (the horizontal opening) for personnel and equipment.
The Wartsila 6L32 mains are the diesel baseline version of the engines in Harvey Gulf’s dual-fuel vessels, Verret said, referring to the class being built at Gulf Coast Shipyard Group in Gulfport, Miss.
The z-drives are Schottel 3030 units. Schottel also supplied three 2,010-hp bow thrusters for precise DP stationkeeping in offshore conditions that often include high winds, waves and currents.
As fitting all things Harvey Sub-Sea, the winch for the 250-metric-ton National Oilwell Varco (NOV) crane is huge, consuming the bulk of space in a room that spans the vessel’s 73-foot beam. The winch, wound with 13,615 feet of 100-mm wire, is set directly on the double bottom of the hull, providing the greatest possible center of gravity for the massive crane above.
The NOV Hydralift knuckle-boom crane dominates the aft deck and is capable of working to depths of more than 13,000 feet. The active-heave compensation system was provided by Hoppe Marine, as were the stabilizing and roll dampening systems.
“The deck plate is 1 inch thick, and wherever there are fuel tanks we’ve built a 30-inch cofferdam over them so that we can weld anywhere we want on the main deck,” Verret said. “We have a lot more flexibility for specialized load-outs, and we can weld on tie-downs or pad eyes wherever they are needed.”
An Ansul foam-dispensing monitor is positioned for any firefighting duty that might arise on the helideck.
There is also a 24-by-24-foot moon pool on the midship centerline of the aft main deck, with a main deck closure. The main deck is rated for 10 tons per square meter, including over the moon pool and the z-drive hatches, Verret said.
“We built in a lot of dedicated storage throughout the vessel, and the stores can be loaded directly into the pantry from the motorized gangway at the embarkation area,” he said.
The first deck contains an online room, an offline room and a conference room dedicated to ROV operations. The second deck has port and starboard ROV rooms that are designed to accommodate all sizes and designs of remotely operated vehicles currently on the market. Sub-Sea’s electrical system is configured to provide power for two 250-hp ROVs.
The fifth deck is exclusively staterooms, with the remainder of the 150 personnel accommodated in staterooms occupying the forward portion of decks one through four. The staterooms, fabricated and installed by Marine Interior Systems (MIS) of Covington, La., are furnished with naturally finished red oak and have satellite TV and Wi-Fi.
Harvey Sub-Sea towers over Harvey Stone at Eastern Shipbuilding’s Nelson Street yard in Panama City, Fla. Harvey Stone, a 220-foot multipurpose field support vessel, was delivered to Harvey Gulf in late August.
MIS installed mineral wool core panels with a sound rating of 32 decibels on the bulkheads and ceilings. “And we used a product called Sikafloor PK-90 N to reduce structural-borne sound on the main and A deck,” said Adam Rodgers, director of business development at MIS.
To further enhance the crew’s comfort and provide relief during long stays offshore, a 63-seat theater, a gym and a lounge are located on the second deck.
“The interior is more of a European design with a central stair tower,” Verret said.
Perhaps to put an exclamation point on Harvey Sub-Sea’s dimensional presence, a massive mast rises above the bridge. Verret said it is also more European in design with more separation between the equipment and antennas, making it easier for maintenance and repair.
“It’s much more robust than the usual pipe mast,” said Eastern’s Winpigler. “This one is specifically designed and structured for all of the high-tech, state-of-the-art navigation equipment on the vessel.”