You might have felt like you had to do some heavy lifting on Monday, but unless your name is Atlas, World Marine of Alabama probably has you beaten.
Over the course of about five and a half hours, the Mobile company guided the Wheeler, a massive U.S. Army Corps of Engineers dredge, into its even more massive main dry dock, the DD-1, and elevated it roughly 28 feet, so that its hull rested high and dry on a carefully positioned array of six-foot-high support blocks.
Visitors to Mobile’s waterfront and boaters traveling the Mobile River see drydocks all the time, sitting there empty or cradling some vessel while it undergoes repair and maintenance work. But Monday’s lift at World Marine of Alabama (WMA) provided a relatively rare chance to watch the transition from empty to loaded.
In a sense, this visit from the Wheeler is old hat: Launched in 1982 after construction at Avondale shipyards in Louisiana, the Wheeler has visited WMA more than once over its lifespan. In 2012 it came to the Mobile-based company – owned by Retirement Systems of Alabama – for a major overhaul that included new engines and drive systems.
“We have a long, rich history with the Wheeler,” said Ryan Roth, vice president of sales and marketing for WMA. Every job is competitively bid, he said, so WMA doesn’t take the work for granted – but it does know its way around the ship.
That knowledge probably comes in handy on a day like Monday. Anybody who’s tried to trailer a small boat in a crosswind can begin to grasp the challenge of inserting a 408-foot-long, 80-foot wide ship into a parking place 668 feet long and 118 wide, with a blustery 15-foot north wind gusting smack into the side of the hull.
The effort got under way a few minutes before 9 a.m. With a single blast of the horn the Wheeler, braced by two tugs, eased away from the dock upstream of DD-1. Within moments it was scudding downriver and downwind, building up momentum that the tugs had to overcome as they turned it sideways and lined it up with the dry dock.
A smaller tug, the Scott Pride, shot around the landward side of the dry dock and bustled down to catch the stern of the Wheeler as it slid into the confines of the dry dock and out of the reach of the larger tugs. At times clatter of exhaust from the Scott Pride suggested the tug was at full throttle as its captain strove to keep the Wheeler off the downwind wall of DD-1.
According to the Corps of Engineers, the Wheeler is 156 feet tall from keel to top of mast, displaces more than 10,000 tons empty and can carry 8,256 cubic yards of dredge spoil sucked up by its three arms. Its 38 crew members can keep it operating 24 hours a day for two weeks at a time. It is the largest dredge of its kind owned by the Corps, which says it maintains waterways from Key West to Brownsville, Texas. (“The Wheeler spends most of its time dredging in the southwest pass of the Mississippi River,” said Roth, adding that the Wheeler does continual “maintenance dredging” to keep a vital shipping channel from filling with silt.)
Despite the great scale involved, Roth said, a ship has to be positioned to within a few inches of its target space within a drydock. Blocks have to be carefully positioned so that they sit under strong points of the ship’s structure and transfer the load to strong parts of the dry dock’s deck.
Laying out the support blocking is “one of the most important work that our engineering group does for all drydocking projects,” said Roth, a Mobile native whose credentials include a mechanical engineering degree from Auburn University.
Mishaps are not unheard of. Last April, for example, a dry dock at the Nauta Shipyard in Poland tipped over while holding a Norwegian tanker. Roth said that WMA’s DD-1 is built in seven sections, each with four tanks, each tank having two pumps. That means that during a drydocking, 56 pumps are individually switched on or off as needed to keep things level and to equalize the strain across the length of the dry dock.
At the beginning of the process, depth gauges on the hull of DD-1 showed that it was 22 feet down to the top of the blocks, with another 6 down to the actual deck. By a few minutes after noon, the dry dock had risen more than seven feet, and the tips of the ship’s propellers were visible above the water. With nine feet indicated, the hubs of the big four-blade wheels were visible and with three feet indicated the props were almost completely clear. As the water dropped below the bottom of the depth gauge, the blocking under the skeg at the rear of the hull peeped above the surface.
At about 2 p.m., Assistant Dock Master Brion Boudreaux made his way down a long staircase to a landing that had just emerged from the depths. After waiting a few moments for water to pour off DD-1’s deck, he walked across to the Wheeler, past a propeller much taller than he was, and began to explore the hallways under the ship, checking to see if the Wheeler was sitting where it should be on the blocking.
By the time two of his coworkers crossed the deck a few minutes later, gulls already had moved in to look for fish stranded as the deck came up.
According to information provided by WMA, the Wheeler will be drydocked for about 60 days. Planned work includes “hull painting, double-bottom tank blasting and coating, hopper door repairs, steel renewals, dredge and jet pipe repairs, bow thruster overhaul, emergency generator replacement, pump and valve overhauls,” and repairs to the system that controls the Wheeler’s variable-pitch propellers.
Roth said the contract is in the ballpark of $6.7 million, though options affect the final total. The work also means jobs, with a substantial increase to WMA’s normal level of roughly 200 employees.
“Our shipyard continues to complete work packages safely, on time and on budget for our customers at competitive prices. This upcoming project on the Dredge Wheeler will be no different,” Robert Beckmann, senior vice president and general manager of WMA, said in a statement about the project. “It is anticipated that we will add approximately 65 craft personnel to sustain our workforce during this project,” he said.
“There’s a base crew and an extended crew. A lot of these guys travel, that’s what they do, they go from one job to the next,” said Roth. “The craft market in this area is very competitive.”
By early Monday afternoon, some of those workers were standing by, ready for the signal that they could haul their equipment onto DD-1 and get to work. All around them was material and tools staged and ready: Stacks of scaffolding, trainers of power-washers, a small fleet of rented lifts that will raise workers up to the hull.
When all the work is done, the DD-1’s tanks will be flooded, its deck will fall below the waves and the Wheeler will float free once again. When it has departed the DD-1 will be ready for its next job. That could be almost anything: An extensive overhaul of another dredge, a short stay for one of Austal’s Littoral Combat Ships, a quick emergency visit by a ship in need of speedy repair.
And if history is any indication, somewhere down the line, the Wheeler will be back again someday, returning to familiar waters so it can be raised out of them.
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Source: Alabama Local News
