The skipper who plucked four people to safety after they were forced to jump from their sinking vessel in Auckland's Hauraki Gulf on Sunday morning said it was just a matter of being in the right place at the right time.

The four were rescued on Sunday morning, after their Labour Weekend outing took a turn for the worse when their boat began to take on water just north of Motutapu Island.

An emergency call was made shortly before 10am as the boat began to sink, forcing its occupants to jump ship.

Within minutes they were plucked to safety aboard a Doctor Hook Fishing charter vessel.


Owner of the fishing charter, Bruce Newbury, said it had been a typical Sunday at sea when they noticed the vessel in distress.

"It had stopped suddenly and then after about a minute the boat turned over to one side," he said. "We noticed the boat was sinking and taking on water.

"We just got all our customers to wind their fishing gear up and we steamed across to the vessel that was in distress."

Newbury said had it happened 10 minutes earlier he might not have spotted the emergency.

"I knew a few of the other guys around. If they had seen they would have done the same as we did; it was just lucky we had a pair of eyes looking in that direction."

Newbury said it was unclear what had caused the boat to sink, as the water was calm.

He said it could have been a mechanical failure or some sort of underwater obstruction.

He said the four, who he described as being in their 60s and of European descent, were in a shock so he didn't question them too much.

The Coastguard arrived quickly and took the four to shore.

Today a Coastguard spokeswoman for the northern region said there were 63 incidents in the water on Labour Weekend, most because of mechanical or electrical breakdowns as boaties hit the water for the first time after winter.

She said as well as the above sinking, there'd also been a surfer in difficulty out in the water, and another sinking in the Rangitoto Channel on Saturday.

On Sunday, there'd been a medical event out on the water, and yesterday another person needed to be plucked from the water near Maraetai.

She said the busiest hour for the coastguard was on Sunday at 4pm - with a total of 120 calls within the hour.

Maritime New Zealand today said six small vessels around the country needed assistance from nearby vessels or the Coastguard.

Rescue Coordination Centre search and rescue mission coordinator Tracy Brickles reminded boaties to check their vessels before heading out.

"This is a good time to check all equipment and maintenance of boats before taking them out on the water,"

Marine Services Auckland's Nick Lewis salvaged a boat believed to be the one that sank in the harbour.

Lewis said it took the whole day to raise the vessel.

He said the boat remained buoyant, with the cabin sticking out above the water, so it was easier for his team to recover.

His tug and barge towed it to shore and it is now in Gulf Harbour.

Lewis believed a leak may have originated from a sensor at the bottom of the boat, but the exact cause of the sinking was yet to be determined.