Gosh Johnny F, It's a brilliant theory, but.....
Manannan has been in service for a long time now. If erosion happens as quickly as you say it does, why hasn't this same thing happened many times before?
And if the boat, and this equipment in particular, has been recently inspected as I understand it has to be every year in dock, why this time round has it only taken a few weeks for the failure?
And just to be clear, unlike NeverAgain, I most definitely am questioning your 'expertise'!