Last night defence chiefs admitted the limitation resulted in the vessels being 'invisible' to the destroyer.
The equipment on board HMS Southampton is installed on ships throughout the Naval fleet. But an emergency safety code is to be introduced by the Navy to prevent a repeat of the shelling near Weymouth, Dorset, last June.
The findings of a top-level inquiry were revealed last night by Archie Hamilton, the Armed Forces Minister, in a letter to Ian Bruce, the MP for South Dorset.
He concluded: 'However, as all the safety procedures then in force were fully complied with, there are no grounds for taking disciplinary action against any of the personnel involved.'
Paul Whittall, of Bournemouth, skipper of Offshore Rebel, one of the fishing boats, said: 'It is commendable that they have investigated it and admitted their own inadequacy with their navigational equipment. But it would have been nice if they had written to me and apologised.'Reuse content