They were about 400m off shore but the teen was struggling with the outgoing tide.
A 20-year-old deckhand, from Mangere, in Auckland, realising the dilemma, decided he would also disembark.
Mr Gorrie said the second deckhand was a stronger swimmer and went straight past his mate to shore where he managed to find a dinghy.
However, lacking a set of oars he instead used a branch to propel himself out to the struggling swimmer, who was thought to be in the water for about 40 minutes.
The teenager and his gear were safely delivered to the shore. Seeing that the two crew were safely on the beach, the commercial vessel motored off.
The duo were given a hot shower at the local camp ground and police took them to Russell, where they stayed with a relative overnight.
"Fair play to the guy who wasn't involved in the argument. Out of concern he has jumped in and saved the other guy," Mr Gorrie said.
"It could have been more serious and even ended with a drowning or one guy suffering hypothermia."
Police are looking for the skipper of the 15m fishing vessel to talk with him about the incident.