The 32-year-old was fishing with friends on the South Alligator River on April 24 when the reptile launched itself out of the water and into the vessel.

Brothers Ben and Riley Wilson of Shoalhaven Heads, and Grant Barlow of Griffith, in the state's Riverina, were all aboard - but Riley saw the croc first.

"The sun had just gone down and we were making some dinner when Riley turned around and shone his torch into the water and there was a croc ready to jump," Ben said.

"Riley jumped up, and the croc just launched itself into the boat - its bottom jaw locked onto the seat, and its top jaw went around Chris' waist.

"It was in the boat flapping around, and then it flapped back around and was out of the boat."

The quick attack stunned the lads into silence; then they realised Mr Perger was bleeding.

"It all happened so fast," Mr Perger said. "It didn't even hurt at first there was so much adrenalin running through me - and then it started to sting.

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"Riley definitely saved my life - once he yelled 'croc' I jumped behind the seat. If it wasn't for him the croc would have had its jaws completely around me."

Plans to spend the night aboard the 5.5m boat dashed, they travelled the 90km back to the boat ramp. And at first light ... they went fishing.

"We're on a three-week trip - we're here to chase the big barramundi," Mr Perger said. "So the next morning we went fishing.

"But after we talked to some other (fishers) they told me I needed urgent medical attention, as crocs carry bacteria in their mouth."

Mr Perger sought treatment at the Jabiru Health Centre, undergoing a surgical procedure and then a course of antibiotics.

"They have to cut away some of the affected skin to get rid of any bacteria," he said.

"There was a possibility I may have had to be flown to Darwin for further surgery, but fortunately that wasn't the case."

Measurements of the teeth marks on his skin led experts to estimate the size of the crocodile as 4.5m to 5.5m.

"If that chair hadn't been between me and the croc, it could have been a different story," Mr Perger said.

A look at the friends' venture 'Southcoast Adventures' and 'Twice Eyewear' on social media shows they're all about 'Exploring Australia and Living the Dream'.

"We're finishing our trip," Mr Perger said. "This hasn't slowed us down."

Crocodile expert Adam Britton said the behaviour was unusual.

"Certainly from the damage done to the seat which the crocodile bit, and also the grazing ... it was a pretty big crocodile," he said.

He said usually crocs would not jump into a boat.

"It's very unusual for a crocodile to do that, to actually come all the way up into a boat," he said.

"So for them to do that, there has to be a very specific reason for it to do it's. If there's a really tempting smell of food, that's a really good reason to do that."

Kakadu National Park staff are searching for the crocodile.

"Crocodiles exhibiting aggressive behaviour are captured and assessed before being relocated," a park spokesperson said.

"Consultation with Traditional Owners takes place before a decision to destroy a crocodile is taken."

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