Maritime New Zealand is reminding people with outdated emergency distress beacons to make sure they are disposed of properly.
A four hour search involving a rescue helicopter was triggered last week by what turned out to be an obsolete distress beacon transmitting in error from a dilapidated yacht near Picton.
Beacons operating on the frequency stopped being monitored in February 2009.
But search coordinator Mike Roberts said aircraft passing overhead could still pick up their signals - and that's what sparked the search.
He said the battery needed to be disconnected and the beacon disposed of correctly.