Mighty Servant 3 didn't float very well a few years back! Pretty impressive how they raised it off the seabed and returned it to service though. I always wondered how they got those container cranes on and off the transport ships until I looked it up on youtube...

It actually floats in exactly the same way as any other ship, in that the weight of water displaced by the bits under the water equals the weight of the boat and everything its carrying. Since each cubic meter of water weighs just over a tonne, it can carry a lot of weight.

I tend to deal even more complicated vessels on a daily basis so its nothing too impressive for me Partially sinking a ship is easy - its fully sinking that's difficult if you're doing it on purpose.

The main difficulty with these ships is that they are very sensitive to weight & trim changes while docked down and that when things go wrong they go wrong very quickly. They can also be very sensitive to changes in water density.

Some big stuff here too its an old thread i started a while ago: http://www.pistonheads.com/gassing/topic.asp?t=108...