His son-in-law Robert and nearby beachgoers ran down to the water.
"There was a guy with a plastic kayak and they signalled him to come over.
"It was his first go in a kayak but he paddled out and tried to tow them back but the rip was so strong it kept taking them out further.
The group on the beach signalled to the kayaker to travel diagonally across the current.
They made it close to shore but the swimmers let go of the kayak, not knowing there were holes in the sand between them and the shore.
"The poorer swimmer got dragged out again. It was pretty alarming, like it was happening in slow motion.
"The guy in the kayak got in again and one of the brothers went back and pulled the other into shallow water.
"We all walked back and thought, that was lucky, but then the 16-year-old's girlfriend came running up the beach to us.
"We could see he was in trouble and Robert rang the ambulance.
"He was in pretty bad shape by then - he was going in and out of consciousness and had hypothermia."
They covered him with blankets until the helicopter arrived. He told Mr Hockey it was his three-quater length jeans that had caused him to get into trouble while swimming.
"The 15-year-old appeared fine but the 16-year-old had taken in a bit of water and was pretty cold and unwell," St John Ambulance Service district operations manager Stephen Smith said.
"As a precaution we decided to chopper them both to hospital."
The younger brother needed no treatment and the other was discharged later in the day.
The identity of the kayaker remains a mystery.
"When the boys were on the beach they just put the kayak into their ute and took off," Mr Hockey said.
"If it hadn't had been for the kayaker they would have been goners - he saved their lives,"