In the tiny inflatable tugging behind him, his two friends used their oars to help paddle toward the Sumner coastline.
Sumner Lifeboat coxswain Blair Quane came across the trio around 40m off Boulder Bay, near Godley Head.
"A member of the public saw the boat having engine trouble and paddling back in with oars, so called us.
"They had one of them in the water swimming with a rope and the two behind paddling.
"We helped them paddle the remaining 40m to shore and saw them there safety then had a chat."
Quane said the trio were not wearing lifejackets, were out of petrol and didn't appear to have any means of communication, such as a cellphone or a flare, with them.
The swimmer towing the boat looked to be in shorts of his underwear, he said.
"He definitely wasn't wearing much and it was 12C or 13C in the water, it was freezing.
"It's not something I would be doing."
While the three were lucky with the calm water and clear weather conditions, Quane urged boaties to keep themselves safe when heading out on the water.
"Always check your engine, wear lifejackets when you're going out on the water and have a radio or at least one cellphone, some method of showing distress."
Quane directed boaties to the Coastguard website for some tips on how to keep safe, and aboard, when out on the water.
Water safety tips:
• Always wear a lifejacket.
• Be prepared and check the weather before you go out.
• Enter a trip report on VHF 02 stating which boat ramp you've left from and what time you will be back.
• If you are carrying a cellphone as a means of communication keep it in a snap-lock bag to keep it dry.
