A boat found smashed on rocks near Wellington yesterday sparked a sea and air search until it was established the catamaran had broken from its mooring.

Maritime police scrambled a boat and helicopter to an isolated bay on Wellington's west coast after a passing vessel reported the wreckage shortly before 11am.

Senior launch master Barry Hart said both the police boat and helicopter scanned the shoreline for any possible victims, and members of the police dive squad were put on standby.

"Our paramount concern was, were there victims?

"We're not in the business of salvaging yachts, we're in the business of search and rescue," Mr Hart said.

However, the mystery was solved once the name of the 9m catamaran was found in the wreckage.

Police confirmed it had previously run aground on D'Urville Island in the Marlborough Sounds and been towed to safety and secured on a nearby mooring.

Wild weather had broken the mooring and the craft had drifted across the Cook Strait.

The boat's Australian owner has confirmed that nobody was on board.

"The owner's pretty disappointed that he's lost his boat," Mr Hart said. "And it is a total write-off; there is nothing to salvage off it."