The three fishermen's vessel didn't have an Emergency Position Indicating RadioBeacon, which transmits a distress signal anywhere in the world through a satellite system, the navy said.
Meanwhile, the coastguard was not alerted to the Purbeck Isle's plight for seven hours as it was not fitted with an emergency position-indicating radiobeacon or similar distress signalling device.
"If the beacon is operating... that's a good sign as a heavy landing can tend to prevent the beacon working, " Steve Rendle from the Rescue Co-ordination Centre New Zealand (RCCNZ), told Radio New Zealand.