A cow shark attacked a rubber duck with two fishermen in it at Melkbosstrand on Sunday, just two days after a teenager was killed by a great white shark at Noordhoek Beach.

Rudolf Bokelmann, 36, and his friend Izak Vermeulen, 26, of Duynefontein got away unharmed.

But they said they had got the shock of their lives when a 2m-long cow shark, which is usually very placid, rushed towards them and tried to bite a piece out of their rubber duck.

On Friday bodyboarder David Bornman, 19, from Newlands, was attacked by a huge great white off Noordhoek Beach on Friday.

He bled to death on the shore minutes later.

Speaking after Sunday's attack, Bokelmann said they had gone about 500m offshore to catch a few kob.

They dropped their anchors and then their fishing lines.

But when they saw that nothing was happening, decided to pull in their bait.

As they were doing so, the cow shark came towards them and lodged its razor-like teeth firmly in the front right-hand side of the boat, where Bokelmann was working.

Bokelmann, whose right hand had been operated on earlier in the week, jumped back in fright.

Vermeulen came forward and stabbed the back of the shark's head eight times.

They grabbed its tail and hauled the shark, which was still alive, on board.

"This is the first time that a cow shark has attacked in all my time on the sea," said Bokelmann.

With the help of other rubber duck crew in the area, they managed to get to shore and report the incident at the Melkbosstrand police station.

The police gave them permission to kill the shark.

Bokelmann said he suspected the shark had been after the bait he was pulling in but that its teeth had got stuck in the rubber duck.

"It's completely unnatural for a cow shark to attack a boat like this.

"In my experience, I found that all sharks are human friendly - provided you are not in their territory," said Bokelmann, a part-time fisherman with 20 years experience.

Vermeulen, who fishes full time and is the owner of the rubber duck, said they would have to patch the front and nose, which would cost about R1 500 to R2 000.

Meanwhile, popular surf spot Noordhoek Beach was temporarily closed on Sunday following the death of Bornman.

The 19-year-old was attacked by a great white while he and five other surfers were enjoying the waves on Friday.

While bodyboarding in the surfing spot near the Kakapo wreck, the great white dragged Bornman under water and tossed him in the air.

The shark's teeth bit into his body causing a massive injury from his back down to his thigh.

He bled to death within minutes despite receiving cardio-pulmonary resuscitation from a fellow surfer.

Jeremy Gardener, 33, one of the six surfers who helped pull Bornman on to the beach, said time had seemed to stand still while he and other surfers were trying to resuscitate the badly injured young bodyboarder.

"There was so much blood," he said.

Gardener said had never seen or been involved in such an ordeal before.

But that the experience had not put him off surfing, as it was all just part of life, he said.

Bornman's father, Phillip Bornman, who is a professor of surgery at the University of Cape Town, was still distraught on Sunday night.

"I cannot describe this feeling to anybody," he said.

"Only those people who have lost a son of that age can appreciate what it is all about," he said.

David Bornman was the youngest of four children.

The others are Inge, 21, Phillip, 23, and Nico, 24.

David was the only one really interested in surfing.

"His interest with surfing came about in high school," said his father.

David matriculated from Rondebosch Boys' High School last year.

He was thinking about studying humanities at UCT next year.

Earlier this year David went to San Diego in California and Bali to work, surf and "find himself".

David Bornman's memorial service will be held later this week.