Police suspect two men who claimed to own a jetski abandoned off the Waipu coast may have stolen another machine from a nearby property.
A businessman from Langs' Beach has offered a reward for the recovery of his jetski, worth about $18,000, and a trailer that went missing on December 23.
The man and his son were rescued from their jetski, about 2km off the Waipu River mouth, that day after going to check cray pots. The son was dropped off home by a rescue helicopter.
His father was picked up by a Coastguard vessel and taken to the Marsden Pt Marina.
Their jetski was seen drifting along the coast, about 400m off the shoreline south of the Uretiti campground, between 6.30pm and 6.45pm on that day. Circling the jetski at the time was a thundercat boat.