I have two 80 year old copper gas tanks in a 1928 Elco. They carry around a significant amount of green sludge which inevitably gets stirred up in a seaway to the point where no amount of filtration can cope. Losing power under these conditions can exciting but is not highly recommended; consequently, I reflect on how I might clean these tanks without blowing up the boat and myself in the process.
There appear to be inspection ports in each tank but with vertical baffles at regular spacings I cant imagine how it would be possible to extract all the crud from the bottom. On top of all this I can't help but wonder if the green sludge isn't some transmogrified copper compound which could mean the tank wall thickness is something less than it was in 1928. Does anyone know what this stuff is and how I might be able to remove it without killing myself?