Even that ferry is pretty large - The Sonoma, part of the Golden Gate Ferry service has a loaded gross tonnage of 265 long tons or about 600,000 lbs. If you assume the ferry was partially sunk and filled with water, let's say an extra 5 feet under water, you'd have an extra 1.8 million lbs to lift (170' * 34' * 10' *… » 4/25/14 4:20pm 4/25/14 4:20pm