In an email seen by the BBC, a serving Royal Navy officer wrote that “total electric failures are common” on its fleet of six £1bn Type 45 destroyers.
The Ministry of Defence said there were reliability issues with the propulsion system and work to fix it would be done to ensure “ships remain available”.
One Royal Navy officer said the cost could reach tens of millions of pounds.
The warning signs were there in 2009 when the Commons Defence Committee published its report on the Type 45.
MPs noted “persistent over-optimism and underestimation of the technical challenges, combined with inappropriate commercial arrangements” leading to rising costs.
Each destroyer ended up costing about £1bn. The Royal Navy wanted 12 ships but ended up with half that number.
The Type 45 has an integrated electric propulsion system that powers everything on board.
Type 45 destroyers: UK’s £1bn warships face engine refit