The 150' Army Corp Dredge CURRITUCK used to dredge Saquatucket Entrance Channel
Text by Tim Wood
Photos by Robin Romano
Its hull opens like a reluctant clam, slowly giving up its contents to the hungry ocean. A seagull that had been happily feeding on eels and minnows squawks and takes flight as the sand beneath its feet begins to break apart and slide away. As its 300-cubic-yard load settles onto the bottom a few hundred feet off Harding's Beach, the Currituck does a slow, graceful turn and heads back to the Stage Harbor channel, where more shoals await the powerful vacuum pumps of the U.S. Army Corps of Engineers' only split-hull dredge. Based in Wilmington, N.C., the 150-foot long, 484-ton dredge spent the past two weeks ferrying sand between the channel and the disposal area, clearing the 150-foot wide, 2-nautical mile long harbor approach to a depth of 10 feet at low water. This week it heads to Saquatucket Harbor in Harwich, where it will spend six days before moving on to Sesuit Harbor in Dennis.
The Currituck, which can dredge up to 3,500 cubic yards of sand a day, is in great demand. "We've worked this year from Florida up to Maine," said Captain Ed Evans, who has been with the vessel since 1980. Like the dredge, his home port is Wilmington, N.C. "Most of the places we go are nice places, like Chatham," he adds in a slow drawl. "It's a real hardship to be in Chatham on the Cape in the summer."
Like the captain, most of the five-member crew hail from North Carolina. They work 12 hours a day for eight days straight before they're relieved by a second crew. Most head home for their days off "just as fast as I can," Captain Evans said, "even when we're on Cape Cod."
Material being pumped from ocean floor into hopper of CURRITUCK Saquatucket Entrance Channel
The dredge operates seven days a week and has little downtime, said mate Bud Gaskins. "Usually the only downtime is because of weather," he said while standing on the deck, shouting to be heard above the sound of water and sand shooting into the hopper through 10, 12-inch pipes. "Very seldom do we have mechanical failures." Aside from Christmas, Thanksgiving and a two or three week period when repairs are made and equipment replaced, "she really works 12 months out of the year," Gaskins said. It costs about $8,000 a day to operate the Currituck, a bill that is paid by the Army Corps of Engineers. "You're tax dollars at work," commented Captain Evans.
In the spacious, air-conditioned cabin of the Currituck, Captain Evans keeps a close eye on the bank of instruments in front of him, occasionally casting a glance to the left at a computer monitor, on which a small boat- shaped object moves in fits and starts past a dotted red line that marks the limit of the dredge disposal area. Pre-dredge survey data collected by the Corps has been programmed into the computer, which keeps track of the Currituck's progress via satelite- controlled global positioning system. It is accurate to within three meters. "That ain't bad at all for a 150-foot boat," the captain pointed out.
Built in 1974, the vessel was originally a barge that worked in tandem with a side-casting dredge. After the dredge filled the Currituck's holding bin, known as the hopper, it would cruise to a near shore dumping area and open the hull, depositing the material. In 1977 the Currituck was converted into a self-contained dredge, modified with two 160-horse power diesel pumps attached to drag heads with 10- inch diameter pipes that act like a vacuum, sucking sand from the bottom of the harbor entrance and spewing a dark-colored slurry mixture into the hopper. As it fills, the vessel rides lower and lower in the water, until the deck is nearly awash. It takes 20 to 25 minutes of dredging to fill the 80-foot long, 8-foot deep hopper; the drag heads can be trimmed when needed to adjust for depth, and the amount of spoil collected can be controlled by adjusting drainage flumes along the side of the hopper.
Sand from channel bottom fills hopper of CURRITUCK Saquatucket Entrance Channel
Captain Evans watches the computer screen, slowing the vessel as the Currituck icon passes the red dotted line marking the disposal area, chosen so that currents would move the loose sand on shore and help build up the beach. Once well within the area, a few hundred feet off Harding's Beach, hydraulic rams at the front and rear of the hopper force apart the twin hulls. Cracks develop in the smooth, wet surface of the collected sand as it begins to sink, slowly seeping out the opening. The decks tilt at an angle as the last particles of sand disappear into Nantucket Sound. The rams can separate the hulls by up to 11 feet. "But its usually only open by one foot," said Captain Evans. "That's usually enough."
Not always under control, here CURRITUCK plowed into center span taking out bridge at Outer Banks
Its cargo dumped, the hulls which are like two huge pontoons come together once again and Captain Evans uses the twin Shottel drive outboard propulsion units to turn the dredge back toward the channel. The outboard units, which swivel 360 degrees and can be raised and lowered, give the huge vessel incredible maneuvering ability. "She'll turn on a dime," said the captain.