"One was actually washed through the front hatch when a big wave hit them ... then the third one managed to get out under his own steam."
The men were left trying to stay afloat with waves of up to two metres in the area at the time. When the Coastguard reached them they were exhausted and clinging onto items from the boat including a chilly bin.
"They were quite shaken and shocked. They were very, very pleased to see us turn up," said Beech.
He said one of the men had a severe cut on his head, while the others were scratched and bruised after being thrown around in the boat. They were treated by ambulance staff at the scene.
Maketu Coastguard's secretary treasurer Geoff Oliver said the men were "very, very lucky".
"When we got them [to shore] they couldn't believe how lucky they were and how scary it was inside the cabin upside down."
Beech said the boat flipped after the skipper decided to overtake the wave instead of follow it.
A second Coastguard boat was sent out to retrieve the overturned vessel this evening however it was unsuccessful. Beech said they would have a second look at the boat tomorrow.
Beech said the local Coastguard were called to about 12 overturned boats at the mouth of the Kaituna River a year.
He said the incidents were normally a result of factors such as the conditions or people not properly preparing themselves.