Re: Cleaning mud off the boat
100 ft long, you would think that would be capable of more than 8 tons of umm, cargo! Just a quick napkin calculation, but 100 feet long, 6 foot diameter tube will displace ~2800 cubic feet, * 63 pounds per cubic foot of water = ~178,000 pounds to get the thing to submerge. Obviously the weight of the sub itself, fuel, engines, etc, comes off that, but still...
(if that periscope is 16 ft high as they claim, there is at least 6 feet of hull above the waterline already. I suspect from the pictures it is more.)