The Coast Guard yesterday said an analysis of corrosion on the hull coating of one of its National Security Cutters (NSC) was an isolated incident, adding that the Stratton returned to full operations in March after being repaired.
The problems with the Stratton, which was commissioned in March 2012 and is the third NSC the Coast Guard has received, were discovered last April and resulted in an emergency dry docking (Defense Daily, May 17, 2012). The corrosion in the aft hull of the 418-foot cutter resulted in leaks.
The Coast Guard told Congress last May that the repairs to Stratton would keep the ship out of service until mid-July 2012 and cost $600,000.
The Coast Guard said that an Engineering Analysis Board concluded that the corrosion was due to damage to the hull coating, which was caused by below-the-waterline welding, and a cathodic protection system that was operating in an “under protect” configuration. The service also said that stray current corrosion from the welding was also a contributing factor.
The board recommended that to prevent similar corrosion in the future that better training be incorporated on the use of cathodic protection systems and to avoid welding on wet hull surfaces.
Visual inspection of the first two NSCs, the Bertholf and Waesche, indicated that the corrosion was limited to the Stratton.
The National Security Cutters are built by Huntington Ingalls Industries [HII]. The Coast Guard plans to buy eight of the vessels, six of which have either been delivered or are under contract.