Rising from stormy seas, the giant turbine towers of an offshore wind farm seem almost miraculous to the untrained eye. But how do you put them there?
Most boats do not have legs. But a jack-up barge has six, protruding high into the air when the ship is in transit.
Extending to a length of 48m from the bottom of the ship, and penetrating up to 5m into the sea bed, the "legs" of these ships provide a stable "ground" in a place where there is only roiling water.
As the legs push down, the ship is lifted above the waves. Purpose-built at a Chinese shipyard, the £60m jack-up barge MPIO Resolution is an extraordinary piece of engineering in itself.
With a solid platform achieved, the windmill is fixed into place using a crane from the ship.
These procedures are becoming more common as the drive goes on to increase wind power.
If government targets are to be met, the UK could have as many as 7,000 offshore wind turbines by 2020. In the process, it would increase the amount of energy produced by that means about 60-fold.
Thats a lot of wind turbines!