Fishing boat sinks off Geelong

A disused commercial fishing trawler has sunk near Geelong and spilled fuel into the bay.

The boat began to sink on Thursday morning at a dock at the Royal Geelong Yacht Club and it is now half submerged in four-metre-deep water.

The boat has been docked at the wharf for more than a year.

A few hundred litres of diesel and oil has leached out of the trawler into Corio Bay, but an onshore wind has kept most of it contained to the inner harbour.

The Oil Response Company of Australia is currently working to clean up the spill.

"The owner is very distraught, but these things happen with old ships and she has just given up," harbour master Captain Dilip Abraham told AAP on Thursday.

"She just quietly went away in the night."

Police, firefighters and Environment Protection Authority workers are on the scene, but there were no reported injuries and no one was on board at the time.