Four of the Royal New Zealand Navy's newest inshore patrol ships are undergoing repairs after cracks appeared in the bridge area.
The Ministry of Defence says all four ships are identical and the cracking is due to a small design fault.
Commander Phil Bradshaw says the cracks are above the water line and there is no risk of water getting into the ships.
Mr Bradshaw says the problem is not systemic, but a fairly common occurence for ships. He says they are all under warranty and the cost of the repairs are being met by the shipbuilders.
Two of the new ships, HMNZS Otago and HMNZS Wellington, had engine problems in July while being delivered to New Zealand.