Fishing boat battle with marlin ends in engine failure

A fishing boat and its crew had to be rescued after it lost a battle with a feisty black marlin more than 30km off the NSW south coast.

The 6.7 metre boat was trawling for fish when it hooked the 70kg marlin at around 1pm on Sunday.

"We were fighting it and it did a U-turn and slammed into the engine," the skipper of the damaged vessel said.

The marlin punched a hole in the engine's canvas cover and cowling, disabling the power.

"It was a freaky thing," the skipper said, according to Marine Rescue NSW which went to the aid of the boat.

The rescue vessel Merimbula 30 undertook a three-and-a-half hour operation to reach the damaged vessel and tow it back to the Kianinny boat ramp at Tathra.

Marine Rescue Merimbula Unit Commander Bill Blakeman said that in his 15 years of volunteer service on the water he's never responded to an incident involving a marlin damaging a vessel.

"I've had a couple of shark-related incidents over the years where they attacked propellers, but never a marlin disabling a vessel," he said in a statement.