Fishing trawler Vellee sank in the Little Minch channel west of Scotland’s Isle of Skye on a calm and clear night last summer apparently without being holed, leading MAIB (UK Marine Investigation Branch) investigators to conclude in their recent accident report that the loss probably resulted from a catastrophic failure of internal sea water piping or fittings – most probably the outcome of advanced electrolytic corrosion.
Fishing Trawler Vellee: Photo courtesy of Skipper JimmyT
Evidence of Corrosion as Probable Cause
A few days before the trawler’s final voyage (from Fraserburgh north-about mainland Scotland to Kilkeel on the east coast of Ireland for better fishing in the Irish Sea) repairs to the main engine were needed, and engineers discovered that two of the eight cylinder liners of the main Kelvin TASC8 engine were badly corroded by electrolytic action; thickness reduced by as much as 85% in some places. An electrician called to investigate, thought that ... [More]
Pipework typically needs to be replaced two or three times during the lifetime of a ship, but arising from recent advances in manufacturing technology there are alternatives to ferrous metal pipework. Dubai-based multinational manufacturers Future Pipe Industries (FPI), who are in the forefront of this developing technology, assert that their GRE (Glass Fibre Reinforced Epoxy) pipes will last the whole lifetime of the ship.
Pipework Safety Issues
Pipes remain unnoticed as they go quietly about their business, which is mainly to convey fluid of some kind (air and gas too) throughout a labyrinth of pipework that invades almost every space in the ship, and which, according to a jointly authored paper by Standard P&I Mutual Insurance Club and RINA, is a system like no other with such enormous potential to cause fire, pollution, and flooding.
Examining the causes of accidents involving burst and leaking pipes, classification society DNV judged that corrosion was one of the majo... [More]
The turbulence of the ship passing through water together with pressure changes due to the propeller, creates hydrodynamic cavitation which produces forces large enough to erode steel.
The unprotected, eroded surface is further degraded by corrosion causing rapid damage to the rudder: a dry dock repair or replacement is the consequence. The Belgium based company Ecospeed recently treated the rudders of four container vessels owned by three different owners claiming to give lasting protection against cavitation damage. According to the manufacturer, the rudders will not require repainting as the surface coating is guaranteed for ten years and will remain intact for the lifetime of the vessels, thereby preventing similar damage from recurring. The Ecospeed solution is to apply a cavitation damage proof coating to the rudder surface using a Surface Treated Composite (STC) of specially formulated glass-flake vinyl ester resin. Ecospeed’s first candidate for treatment was the RoRo MV Elisabeth Russ in 2004. Since then their treatment has been applied to 110 rudders. Not one has suffered from further cavitation damage and none has needed to be recoated. [More]
Modernization and mission improvements will extend USS Bonhomme Richard’s service life
By Edward Lundquist
Photos by Chief Mass Communication Specialist Joe Kane
USS Bonhomme Richard (LHD 6) is currently at NASSCO Shipyard in San Diego for a nine-month, $101 million dry-dock planned maintenance availability period. The repairs to the 844-foot amphibious assault ship will be completed by July 2011.
The 40,358-ton Bonhomme Richard is a Wasp-class LHD, built by Northrop Grumman Ship Systems Ingalls Operations in Pascagoula, Miss., and currently assigned to the Naval Surface Force in the Pacific Fleet.
The first seven ships of this class have two boilers, two geared steam turbines, two shafts, 70,000 horsepower. The newest member of the class, USS Makin Island (LHD 8), has two gas turbines and two shafts delivering 70,000 total shaft horsepower, as well as two 5,000 horsepower auxiliary propulsion motors. Wasp-class LHDs can attain speeds of greate... [More]