The 21m vessel Wind Transfer suffered gearbox problems, resulting in water flooding the engine room.
The two crew members on board immediately sent out a mayday message. HM Coastguard confirmed it received a mayday call from the windfarm support vessel approximately 2.5 nautical miles north-east of Blyth Harbour just before 10.15am.
Both Blyth RNLI lifeboats, Newbiggin lifeboat and Blyth Coastguard were called out. The lifeboats put pumps on board but could not stem flow of water. Blyth RNLI lifeboat escorted the vessel into the harbour.
Northumberland Fire and Rescue Service were called to Battleship Wharf for additional pumping but the flooding could still not be stopped so the Blyth-based boat was lifted out of the water for repairs.