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Tidewater Inc., the New Orleans-based offshore giant, recently added three 250-foot supply boats to its fleet just months apart. The newbuilds can carry as much liquid mud and other drilling fluids as larger vessels in its inventory. The offshore service vessels (OSV) were designed and built by Leevac Industries LLC of Jennings, La.
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| Chief Engineer James Anderson Jr. in front of three Caterpillar C18 generators rated at 340 kW at 1,800 rpm. Pat Tillman has eight liquid mud tanks. “Our engineering department packed a tremendous amount of carrying capacity for a 250-foot vessel, says Christian Vaccari, Leevac’s president. (Photo: Brian Gauvin) |
The lead vessel carries a distinguished name: Pat Tillman. Tillman was a safety for the NFL’s Arizona Cardinals who enlisted in the U.S. Army eight months after the attacks on Sept. 11, 2001, and was killed in action in Afghanistan in 2004.
In honoring a fallen hero, Tidewater followed a precedent it established four years ago when it named a 207-foot OSV, Jonathan Rozier, after a U.S. Army lieutenant from Texas who was killed in Iraq in 2003.
Pat Tillman has a length of 250 feet, a beam of 59 feet and a hull depth of 19 feet. The vessel was delivered in June 2007; Delatte Tide joined the Tidewater fleet on Oct. 1, 2007, and Brewster Tide was the first U.S. commercial vessel to be registered in 2008, on Jan. 2. All three OSVs were designed, built and certified DP-2 to operate anywhere in the world, and Brewster Tide was sent to West Africa shortly after leaving Leevac.
Pat Tillman and its sister vessels have double bottoms with separate tanks for ballast water, fuel oil, potable water, sewage, oily water and dirty oil.
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| Above, Capt. David DeSoto (left) and Second Mate Ryan Daly at the forward console, waiting to load supplies at the Midstream Fuel Service dock on Pelican Island in Galveston, Texas. (Photo: Brian Gauvin) |
Above the double bottom is the machinery space, laid out for maximum efficiency. Aft of the forepeak ballast are the two tunnel bow thrusters, consistent with the vessel’s DP-2 rating. The bow thruster compartment is just aft of the thrusters with a pair of Caterpillar 3508 diesels, each rated at 1,050 hp, driving each of them.
Next are a pair of LeRoi 150 hp air compressors surrounded on three sides by dry bulk tanks, each capable of holding 1,650 cubic feet of dry material. There is a fourth tank behind one of the others along the centerline of the boat.
“This vessel was a Leevac design and our engineering department packed a tremendous amount of carrying capacity for a 250-foot vessel,†said Christian Vaccari, Leevac’s president. The vessel has eight liquid mud tanks, six along the sides of the boat and two along the centerline.
Two of the tanks are made of stainless steel. “The stainless steel tanks give Tidewater the option of carrying methanol or using those tanks for liquid mud or other liquids,†said Vaccari. “Otherwise, tanks would have to be dedicated for methanol only, excluding their use for other liquids.â€
“While they are designated outboard tanks, they are not along the shell of the vessel,†added Mike Jannise, Leevac’s engineering manager. “They are inboard of smaller fuel tanks so they are protected from damage and meet IMO (International Maritime Organization) requirements.â€
From mud to methanol
In all-liquid-mud mode, the vessel can haul 9,720 barrels of drilling fluid, an almost unheard of quantity for a 250-foot boat; typically it takes at least a 280-foot supply vessel to carry this much. When methanol is the cargo, maximum capacity is 2,100 barrels.
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| Pat Tillman was just 27 when he was killed in Afghanistan, where he was serving with the 2nd Ranger Battalion. His posthumous awards included the Silver Star and the Purple Heart. |
Other transferable liquids include 186,000 gallons of fuel oil, 280,000 gallons of ballast/rig water and 33,000 gallons of potable water.
Aft of the tank farm is the engine room, dominated by two Caterpillar 3516 diesels, each rated at 2,575 hp. Between the main engines are three Caterpillar C18 generators, each developing 340 kW of electrical power.
The main engines are connected by shafts to Steerprop z-drives rated at 2,500 hp each at 1,800 rpm. Each unit has a four-bladed, fixed-pitch NiBrAl propeller, complete with a Steerprop stainless steel-coated nozzle.
On the main deck forward is the anchor chain locker. The rest of the enclosed space is devoted to crew comforts such as the galley, a mess with seating for 22, a pantry, a cooler, a freezer, a laundry and changing room and a head. Also on this deck are the emergency generator room and a two-person stateroom. The emergency generator is a Caterpillar C9 rated at 175 kW and is radiator cooled with its own switchboard.
The balance of the main deck is the cargo area, which can hold 8,500 square feet of whatever a rig or platform needs.
On the forecastle deck are three four-person staterooms, two two-person staterooms and a lounge. One of the four-person staterooms can be converted to a hospital to meet the requirements for inpatient service. The 02 deck has two four-person staterooms and two two-person staterooms, plus single staterooms for the captain and chief engineer.
The pilothouse sits atop the 02 deck. The communications suite includes a Furuno A3 communications system complete with a 150MF/HF radio, Inmarsat-C satellite radio, GPS module, NBDP modem and two printers. Other communications equipment includes a Furuno SSB radio, a Furuno automatic identification system, two ICOM VHF radios and one Raytheon loudhailer with two horns.
Built-in redundancies
The navigation systems include a pair of Furuno radar systems with 21 inch CRT display, one Reflecta Anschutz magnetic compass, one Furuno echo sounder and a Furuno electromagnetic speed log with transducer.
The main navigation system is a Kongsberg SDP21 ABS-certified DP-2 system. To meet DP-2 requirements, it has several redundancies, including two SDP-OS operator stations, a dual-redundant controller unit, a pair of master gyrocompasses, two motion reference units, a pair of Gill wind sensors, two uninterruptible power supplies, two Trimble DGPS units and a cJoy independent back-up joystick consisting of a cJoy operator terminal and a cJoy controller unit.
There is also an alarm printer and a fan beam with interface, plus a switch-over unit for the gyrocompasses.
There are a pair of steering stations in the pilothouse and one in the machinery spaces. This equipment is by Steerprop and has azimuth and propeller speed control.
In addition to the three OSVs from Leevac, Tidewater has had a pair of supply vessels delivered in the last year or so from Quality Shipyards LLC, its captive shipbuilder. These are Dalfrey Tide and Barthel Tide (named for Bobby Barthel, Quality’s long-time general manager).
With rig counts growing in markets well beyond the Gulf, worldwide players such as Tidewater will no doubt continue to build vessels that can work anywhere in the world.
