Bender building six anchor handlers for Seacor Marine
Above, anchor handler John Coghill at its christening at the Bender shipyard in Mobile, Ala. The 265-foot anchor handler has a diesel-electric power plant comprising five Caterpillar generators producing 10,750 horsepower. (Courtesy Bender Shipbuilding and Repair)
In early May, Seacor Marine LLC of Houma, La., christened the first of six anchor-handling tug supply (AHTS) vessels built by Bender Shipbuilding and Repair of Mobile, Ala. The 265-foot-by-52-foot vessel completed sea trials in August and is now serving customers in the Gulf.
"We launched the second vessel in July, and the other vessels are in various stages of construction," said Frank Terrell Jr., sales manager for the shipbuilder.
The AHTS is named John Coghill after a retired Seacor employee who oversaw construction of the first two vessels.
AHTS vessels perform multiple support functions for the oil platforms they service. As well as towing them into place and anchoring them on location — and relocating them as needed — they have significant cargo-carrying capability and crew transfer space. They also pack more power than traditional platform supply vessels.
"We call this vessel one of our 'flex' series boats," said Tim Clerc, project engineer for the new Seacor AHTS series. "Seacor has a basic hull design starting at 220 feet, and it can be flexed out to greater lengths by adding modules for more mud capacity, a longer rear deck or special features, such as winch equipment for anchor handlers and methanol-carrying capacity such as in John Coghill," Clerc added.
John Coghill has an environmentally friendly diesel-electric power plant with very low emissions, reduced noise and low vibration in accordance with IMO Regulation A468.
The quad engine main power plant produces 10,750 hp and features three Caterpillar 3516B diesels each running 1,825-kw generators. There is also a 425-kw generator driven by a Caterpillar C-18 engine, and one Caterpillar 3516C diesel powers a 2,100-kw generator.
These engines are placed far forward in the hull. In a diesel-electric configuration, there are neither shafts nor shaft alleys that use up critical space and limit placement of other mechanical machinery in the hull. Electrical cables transfer the power from the generators to twin electric motors that turn the propellers in nozzles.
This AC-drive system also uses some direct current, and there is an MV 3000 inverter to handle this task.
The five generators also supply electric power throughout the ship, eliminating the need for separate gensets, except for a SOLAS 150-kw emergency generator powered by a Cummins diesel.
The vessel features two 800-hp bow thrusters with constant-pitch propellers manufactured by HRP, a Dutch company. An 800-hp thruster is located aft. The thrusters, two fixed-pitch main propellers, four main generators and a pair of independent fishtail rudders are key components in the ABS-rated DP-2 system by Converteam, formerly an Alstom company.
John Coghill was also designed as a methanol carrier, reflecting the increased use of this alcohol in deep-water applications. "This vessel is designed to safely and efficiently transfer methanol from the vessel to the drill rig or other offshore vessel or platform," said Clerc. "The hydraulic pumps are enclosed in cofferdams for safety."
Methanol is one of several fluids drilling contractors can use in the hydrocarbon production stream for deep-water projects to inhibit gas hydrates from forming and blocking a well. These hydrates can form at temperatures well above the freezing point of water when high pressure is exerted on a hydrocarbon gas/water mixture.
In addition to carrying up to 2,422 barrels of methanol, the vessel can carry 4,892 barrels of liquid mud. "The methanol tanks can also be used to carry liquid mud, if the need arises," Clerc said.
This vessel was designed as an anchor handler with the capacity to carry significant quantities of transferable liquids. Fuel oil capacity is 140,000 gallons and drill water, including ballast, is 213,500 gallons. Dry bulk is 7,500 cubic feet, carried in five tanks located along the centerline of the keel. There is also 104,603 gallons of fresh water. Both the freshwater and fuel oil tanks have discharge meters with printers to validate the amount of these two liquids being delivered.
The vessel has the deck size, strength and equipment to fulfill its anchor-handling mission. The key component of an anchor handler is the main winch, in this case a Rolls-Royce Brattvaag electro-hydraulic two-drum reverse waterfall unit with 300 metric tons of line pull to lift and move the anchors. Each drum has 6,600 feet of 3-inch wire. There is almost 10,000 cubic feet of storage capacity for anchor chain.
A pair of shark jaws and two towing pins are also part of the towing system. And there is a stern roller to help lower anchors over the stern and retrieve items being brought on board, with a pair of electro-hydraulic tugger winches with 11 metric tons of pulling power.
The rear deck is 162 feet by 41 feet, allowing plenty of space to carry anchors and the cables that connect them with the platforms they are holding in place.
Maximum speed is 14 knots with a 12-knot cruising speed and an economy speed of 10 knots.
Accommodations on board John Coghill include one-person staterooms for the master and chief engineer and a pair of two-person staterooms for officers or VIPs. Crew spaces include four two-person rooms and one four-person room. All have individual heads.
Beyond crew accommodations there are six two-person rooms and three four-person rooms. Other spaces include a hospital room or four-person crew room with a head. There is a smoking lounge and a nonsmoking lounge that doubles as an exercise room and a mess room.
The pilothouse electronics include a fully integrated Converteam diesel-electric package with DGPS, engine control, DP-2 and a gyro. The navigation package is by Furuno/JVC and includes one S-band radar and an X-band radar. Also in the pilothouse is a GMDSS communications package for area A3 that covers the most distant parts of the Gulf. The steering system is electro-hydraulic by EMI of New Orleans.
Other equipment includes a pair of firefighting monitors, two Flygt liquid mud agitators per tank, and rescue boats and survival craft per SOLAS regulations. Deadweight at 15.5 feet is 2,784 metric tons.
John Coghill is classed by ABS as ABS+ A1, (E), Towing Vessel, +AMS and DP-2.