An affectionate name given to the sludge boats, which, as a result of Joseph Bazalgette’s re-making of London’s sewage management system in the mid-Nineteenth Century, used to do regular passages from the main sewage-sludge catchment facilities east of London, out to a local deep off Foulness, where the ‘bovril’ was dumped into an ebb tide. The fleet was retired in 1998 apparently.
So, all in all, you could reasonably suppose that the Leaky Hulk is just one remaining bovril boat, still shovelling shit - at any rate as far as the scamdemic goes.
Btw, do I pick up from Jamie’s recent link that dear Der is having yet another of his periodic flounce-outs, in high dudgeon about the way that even the regular bovril handlers there are failing to live up to his stratospheric quasi-anarchist standards? 
God, I’m well out of that heavily come-down forum. At least 5F is no bovril boat.
PS: Tickles me pink to think of odd members of the shoveller crew visiting here quietly, and fuming as they have to remain silent - or register, and then suffer the humiliation of having to abide by our basic courtesy rules, or else get bovrilled out again!