In the last month I have come across two situations which highlight the potential problems with skin fittings, reports Eugene Curry. One vessel, a GRP sea angling charter boat, was a licenced Passenger Boat (12 passengers and 2 crew) permitted to operate up to 40 nautical miles offshore. The other vessel was an aluminium hulled yacht undergoing inspection for renewal of its passenger Boat Licence and permitted to operate up to 30 nautical miles offshore. In both instances the owners grumbled about the additional expense involved but changed their tune when problems were found.
Without revealing too much data the following is pertinent:
The vessel was approx. 33’ 04” in length, of GRP Hull and Superstructure, built in the UK in 1992. All underwater skin fittings were of bronze. The vessel had twin inboard diesels and was sub-dived into 6 compartments below the main deck. In 2011 and 2012 the owner had replaced the original bronze sea valves as a matter of routine. The replacement valves were stainless steel. Electrical services were 12 Volt DC with 220 volt AC inverters. The sea valves had no bonding wires.
All the through hull fittings removed had started to turn pink from dezincification. Some were wasted sufficiently to run the risk of failing suddenly.
The vessel was approx. 49 feet in length and of aluminium hull and superstructure built in the UK in 1979. Mast was triple spreader with keel step. Vessel was fitted with an inboard diesel. Electrical systems were 12 and 24 volt DC. For licencing purposes all internal fuel lines were of stainless steel. All through hull fittings were of aluminium. These were specially designed screw down units. The vessel had been rewired in or around 2000.
The sea valves were original to the vessel and the government surveyor insisted on their being opened up for inspection. The valve seat had no rubber washer but relied completely on forming a seal with the shape, similar principal to engine valve design. On one the seat had wasted completely meaning that even when the screw was in the closed position the valve was ineffective.
Everyone should be aware of the dangers in mixing materials, the lack of correct bonding between skin fittings and the vessel’s earth system.
Those engaged in coding of commercial vessel, in particular, should carefully consider the risks to the public and their and their certifying bodies reputations should an incident occur to a vessel they have considered compliant.
The information should also be considered by those involved in conduction Pre-Purchase and Insurance Condition Survey Reports. In the event of a casualty, a court considers the surveyor liable for loss.
Article written by Eugene Curry MIIMS