Fall 1998
Offshore SEA CUSHION Marine Fender Developed for Deep Sea Drilling Ship
Above, the six Offshore SEA CUSHION Marine Fenders await deployment aboard the Glomar Explorer.
In response to customer need, Seaward has produced a heavy-duty Offshore version of the SEA CUSHION Marine Fender. The first demonstration of this new Offshore SEA CUSHION Fender was on the ship Glomar Explorer. Global Marine, Inc., of Houston, Texas, has entered into a thirty-year lease of the ship to initially carry out a five-year deepwater-drilling contract with Chevron and Texaco in the Gulf of Mexico.
The 618-foot (188m) Glomar Explorer was originally designed by Global Marine for salvage operations by the U.S. Government in the 1970’s. As Global Marine knew from overseeing its construction and operating it for the U.S. Gov’t, it also had enormous potential as a deepwater drilling ship. With a designed cargo capacity of 25,000 tons, it could carry six times the drilling equipment of any semi-submersible and was outfitted with a triple redundant dynamic positioning system. These capabilities raised the standard for drillships and equipment suppliers alike.
The Global Marine operations team selected Seaward to design and manufacture six 8-foot diameter, 16-foot long fenders (2.4 x 4.88m).
Photo courtesy of Global Marine.
So Seaward engineers went to work developing a heavy-duty version of the SEA CUSHION Fender by analyzing the dynamic conditions that could be imposed on it from average seas of 8-18 feet (2.5-5.5m) and the special handling requirements specified by the Global Marine operations team. The outcome: Seaward’s “Offshore” SEA CUSHION Marine Fender.
This husky new fender boasts a thicker outer skin than our Standard SEA CUSHION Fender. The increased capacity closed cell foam core absorbs 40 percent more energy while protected by an upgraded tire and chain net. In accordance with contractor requirement, the net supports three times the weight of the fender so that the entire fender system can be deployed and retracted in a single handling. Seaward increased the capacity of the tire and chain net by enlarging the galvanized chain size from 1/2-inch (13mm) to 3/4-inch (19mm) and designing new heavy-duty end fittings. Further, we began using aircraft tires, which have an increased tread thickness of nearly two inches as well as an ample sidewall.
As a result of the design upgrades for the Offshore SEA CUSHION Fender, a number of these features have now been incorporated into Seaward's Standard SEA CUSHION Fender. For example, all SEA CUSHION Fenders (both Standard and Offshore)are now made with heavy-duty aircraft tires and with upgraded chain in the nets.
An extensive retrofitting of the Glomar Explorer was completed in June. The vessel is now capable of drilling in water depths of 7,500 feet (2,286m), easily upgraded to 10,000 feet (3,048m), while under winds of up to 65 knots. Our new Offshore SEA CUSHION Marine Fenders, we are confident, will provide the heavy-duty, low-maintenance, and long-life protection demanded of them.
For more information on Seaward SEA CUSHION Marine Fenders, please contact Seaward.