The Battleship staff understands that the cofferdam and walkway construction projects are complex. It is hard not to wonder what is going on! We encourage the public to ask questions, which can easily be done through our Facebook page, and we will do our best to keep everyone informed!
Take a look at the very informative article the Port City Daily wrote on the construction!
Be sure to check back frequently for more information!
**The Battleship NORTH CAROLINA will remain open to the public during construction**
- A cofferdam is a watertight structure built to allow the enclosed area to be pumped out, creating a dry work environment.
- The Battleship cofferdam will enable workers to repair and restore the ship’s corroded hull, which is paper-thin in places. The Battleship’s last major dry docking and repair work was done in 1953. It is long overdue!
- The cofferdam will be constructed over 18 months by Orion Marine Group of Norfolk, VA.
- 50′ tall
- 1,909′ long around perimeter
- 1,206 steel sheet piles
- 229 vertical steel H-piles, 55′ long
- 229 battered steel H-piles, 60′ long
- 4.6 million pounds of steel (2,300 tons)
4 slide gate weirs, 10′ 6″ tall x 6′ wide
The SECU Memorial Walkway
- Under construction simultaneously, the SECU Memorial Walkway will be a half mile long, 10-foot wide timber walkway surrounding the Battleship.
- The SECU Memorial Walkway will be above the water line but below the main deck of the Battleship. It will enable visitors to see the ship’s entire hull for the first time.
- The SECU Memorial Walkway will include five bump-out areas to honor each of the five branches of the military–Army, Navy, Marine Corps, Air Force and Coast Guard. The Merchant Marines will be honored by flying their flag on the quarterdeck.
- The SECU Memorial Walkway will be open to the public and free of charge.
Q: When the water and muck is pumped away from the ship, how will they shore the Battleship to keep her from listing?
A: The ship is settled in approximately 25’ of mud. The cofferdam will allow us to access the portions of the hull (about a 10’ band we call the “wind/water line”) that needs to be replaced, but we will not remove all the water and mud from around the entire ship at one time. Enough water and mud will remain to ensure the stability of the Battleship, similar to what was done on the USS ALABAMA. The condition around the ship when we drain the water will be similar to that we experience now at low tide. We will simply have more control over the amount of water around the ship while we replace steel.
Q: Are you driving sheet steel into the muck?
A: Yes. The steel sheet piles, steel “H” piles, and timber piles for the walkway are all being driven into the mud and limestone layer that exists about 42-50 feet below the ship. Engineers have carefully calculated the specific depth of each pile to ensure the cofferdam and walkway are able to withstand the various pressures on all sides during all tidal conditions and those we will create during maintenance periods. We’ve conducted several geo-technical studies, as well as a test pile analysis, to confirm the subsurface conditions and holding strength of the mud and limestone.
Q: With construction of the cofferdam are there provisions being made to be able to get the Ship out of the cofferdam and into the river if necessary? Such as locks or doors on the end of the cofferdam?
A: Unfortunately, the Battleship’s condition prevents her from leaving her berth, however, the cofferdam will be equipped with 4 Weir Slide Gates that will open and close so that water can be pumped in and back out of the inner area.
Q: What will happen to the portion of the hull that is in the mud? Does the mud protect it from corrosion or will that eventually need to be excavated to make repairs?
A: The ship is settled in approximately 25’ of mud. The portion of the hull that is currently in the mud has been largely protected from corrosion due to lack of exposure to the elements. The cofferdam will allow us to access the portions of the hull (about a 10’ band we call the “wind/water line”) that has been exposed to the elements for nearly 60 years!