I recently saw a massive new crane at a ship-repair yard. Something like this one: What surprised me was that for such a massive construction the load limit said "only" 300 tons. I seem to recall much smaller road moving cranes (say Demag) with a 300 ton lifting capacity. http://www.p-wholesale.com/upimg/19/741a2/300ton-all-terrain-crane-qay300-106.jpg So what makes these dock cranes special & so massive (I guess expensive too!) Is it the reach, i.e. the moment? What do they use them for that cannot be accomplished with a mobile 300 ton crane?