As many people have already suggested a suction dredger, like the Donald Redford that gets mentioned on the radio chatter in the Solent. Would need the environment extending North and South a few miles though, she operates out of Fareham reach, to the North of Portsmouth Harbour, and tends to dredge in the Nab area off the East coast of the Isle of Wight.
Other than that an old tramp steamer, one of my favourite maritime books is still Ocean Tramp.