Meanwhile, Mr Frost was fighting his way out of the boat. When it rolled he became trapped inside. "I was stuck in the boat, getting forced back in by each wave as I tried to get out. I tried to get a mayday call out but the radio was hanging by a wire," he said. "I knew I had to get out. I was in the hull running out of air."
With a deep gash to his head and blood pouring out, he managed to get free. But he could not see his mates.
"I hopped on the upturned hull and the guys were nowhere to be seen. I started yelling."
He then set about tying ropes on the boat into handles so he had something to hold on to when the waves thrashed him.
"Then I saw the guys about 30m away. Buzz [Mr Kronfeld] was dragging the skipper and they were getting smashed by the waves."
Once the pair were back at the boat they too grabbed ropes and hung on for their lives.
The damaged vessel started to float out to sea and the men began to fear they would not make it home.
"We were shaking, we were pretty cold," said Mr Frost. "We were looking to the heavens waiting [for a rescue helicopter] but there was nothing. I said my goodbyes. I said my goodbyes a couple of times, actually ... I knew the situation was bad.
"In that first half hour I was pretty convinced we were not going to make it through. I was thinking, 'There's probably no way out of this ... so this is how it ends?"'
When the men did not make contact within 30 minutes of logging their bar crossing, an alarm was raised. A rescue helicopter, two boats, the Westpac rescue helicopter and police Eagle helicopter were dispatched.
By the time the rescuers got to the bar, there was no sign of the men. Almost three hours later the wrecked boat finally started to drift back towards the shore but the stricken trio had no idea which shore they were headed for.
Their relief was enormous when they saw land but there was still a treacherous journey to safety - they had to get past the surf line where giant waves were thundering into the beach. "We had to get away from the boat ... We had to get away from it, we didn't want to be anywhere near it when we hit the line," said Mr Frost.
If they had stayed near the boat it could have slammed into them and seriously hurt or killed them.
Mr Kronfeld said the swell was "violent" as they tried to swim the last 400m to shore. "We all got in the water and the next wave, we were all separated. The last time I saw Potter he was lying on his back."
Mr Frost and Mr Kronfeld got to shore but there was no sign of Mr Potter. "I told Oisin to stay and look out for him and I would try and get help," Mr Kronfeld said.
The men had come ashore at Irwin's Gap south of the Manukau Heads. "I waited for 15 to 20 minutes but I was so cold. I was shaking so much, I couldn't see, I had to go ... " said Mr Frost.
The pair were sure they would not see their mate again. They were taken to a local farmer's to wait and Mr Kronfeld said a wave of euphoria washed over him when searchers said Mr Potter had been found alive.
Mr Potter was airlifted to hospital and had surgery this week. He will be in a wheelchair for about a month and then faces months of rehabilitation.
"But he's alive," said Mr Kronfeld.
"We are so very fortunate. It could have been very different. We did everything right, but the unexpected still happened. I don't know what to say to show how grateful, appreciative we are to the Coastguard, and everyone who helped in the search."