Tuesday, January 30, 2007

Another small observation

The 2004 Formal Investigation into the sinking of the FV Gaul concluded, as we all know by now, that the cause for the loss of the vessel was the ingress of a large quantity of seawater through the two duff and offal chutes openings in the hull of the vessel.
The double-barrier protections of these openings – the inner covers and the outer flaps - were found to be in the open position during the underwater survey in 2002.
The fact that the outer flaps were found open, the investigation concluded, was due to seizure caused by corrosion in the vessel’s 16 month old flap hinges and failure on the part of the crew and shore maintenance staff to identify and rectify this problem.
The fact that the inner covers were also found open was explained away by crew negligence. However, the trouble with these findings (as we have attempted to explain in our earlier posts) is that they were based on unsubstantiated assumptions.
Let’s take, this time, the presumed corrosion at the flap hinges. (For a few more details on this issue please click HERE.)
As the same combination of materials, mild steel and brass, had been used in a number of other structures on the Gaul (e.g. for the toggles and clips on all weathertight hatches and doors), one would expect similar corrosion problems in those areas.
In reality, though, this doesn’t seem to be the case.
Quite the reverse, as the following clips[1] show, even after 28 years under the sea, the toggles and clips on the Gaul did not present such a level of corrosion and seizure that would prevent them from being easily unscrewed by the ROV[2] arm.
[1] Extracts from the 2002 MAIB video footage - © Crown copyright
[2] Remote Operated Vehicle

weathertight hatch mild-steel clips & brass bush

weathertight hatch brass toggle & steel toggle bolt

weathertight hatch brass toggle & steel toggle bolt

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