Police say a possible sighting of missing Marlborough boatie William Kerry Blair on Monday has been checked out but it wasn't him.
Search coordinator Bill Talbot says they still don't know what Mr Blair's intended destination was when he left Erie Bay in the Marlborough Sounds in his 9m aluminium launch Erie on Saturday afternoon.
Weather and sea conditions since then have been good, and Mr Blair is considered a capable seaman.
The boat is equipped with a marine radio and a locator beacon, neither of which have been used.
Sergeant Talbot says police are continuing to appeal for sightings over marine radio.
A plane carrying three search and rescue spotters has searched the coast from Nelson to Westport but on Wednesday.
Mr Talbot said that, with no idea of Mr Blair's intentions, it was like looking for a needle in a haystack.
The Erie has a hard top, painted white, and a blue stripe along the side.