A wave power generator for an offshore electricity scheme has been tipped into the sea off the Suffolk coast.
The generator was being towed out to sea to begin a year-long trial when the accident happened near Southwold.
The floating generator owned by Trident Energy was under tow to a new location, a coastguard spokeswoman said.
The capsize happened five miles offshore at lunchtime on Sunday and the unit has now been made secure, owners Trident Energy said.
Great Yarmouth Yarmouth Maritime Rescue Coordination Centre watch manager Mario Siano said: "The floating generator was later connected to a tug and grounded three miles south-east of Southwold harbour entrance.
"All appropriate authorities have been informed. The Marine and Coastguard Agency counter pollution officer is aware and is monitoring the situation."
A spokeswoman for Trident Energy said: "The company is in the process of making arrangements to move the platform to a suitable location where any damage can be fully assessed before determining next steps."
The statement added that the was not connected to its technology for converting "sea wave energy into electricity".
The machine was designed to stand on a giant pair of legs, supported by submerged pontoons anchored to the sea bed which hold it above the waves.
Special floats move up and down with the waves to drive generators, which convert the motion into electricity.
The generator is owned by Trident Energy