The navy's two warships, the Anzac frigates Te Kaha and Te Mana, both broke down at sea earlier this year, it has been revealed.
Both ships had engine problems and it is also believed the navy's supply ship, the tanker HMNZS Endeavour, had an engine breakdown which left it drifting briefly in the Hauraki Gulf last month.
Te Mana had problems with its diesel engines during exercises as it crossed the Tasman to Sydney with its sister ship.
The navy said Te Mana could not use its diesel engines, designed to allow the ship to cruise at a lower economical speed, and had to run its gas turbine.
The gas turbine is a marine version of the engines fitted to a Boeing 747 jumbo jet and allows short, high-speed sprints at more than 27 knots.
The following month Te Kaha had an engine failure as it was about to undertake a replenishment at sea with Endeavour in the Hauraki Gulf.
The engine failure put "an abrupt halt to proceedings" and the frigate broke off the replenishment and stayed at sea an extra night.
The navy could not say what caused the problems.