A MARINE crew eradicating crown of thorns starfish on the Great Barrier Reef has inadvertently saved the life of a young Gordonvale man who was desperately clinging to a navigation buoy 30km off Cairns.

The 24-year-old man had been through a hellish few hours on Friday morning during which his father died and the boat from which they were spearfishing slipped its anchor and drifted away.

Crown of Thorns Targeted Control Program project manager Steve Moon, whose crew rescued the 24-year-old, said it was “pure luck” their boat named Hero was travelling through Luggers Pass near Arlington Reef.

The tragic series of events began earlier that day when the father and son were spearfishing at Arlington Reef.

While the men were in the water their 6m aluminium boat’s anchor slipped and the vessel drifted away.

The 56-year-old father then suffered a medical condition leading the son to desperately attempt CPR in the water.

Exhausted and with no other option, Mr Moon said the son was forced to leave his father’s body and drift about 5km until he was close enough to the buoy where he stayed for an estimated four or five hours.

“It’s a tragic story,” Mr Moon said.

“He was just very, very lucky that we came through when we did.

media_camera HERO: Crown of Thorns Targeted Control Program project manager Steve Moon and his boat crew rescued the 24-year-old Gordonvale man near Arlington Reef. PICTURE: STEWART MCLEAN

“Without a doubt it saved his life. I don’t know how much longer he could have held on.”

Mr Moon said the young man was so exhausted he passed out while clinging to the buoy. “He was just shattered when we got him on the boat,” he said.

“Not just the emotional side of things but also the physical effort.”

All crew members on Hero were trained in senior first aid and placed the 24-year-old on oxygen while they radioed for help from Water Police.

The 56-year-old man’s body was later recovered near Upolu Reef by a rescue helicopter.

Water Police Cairns officer-in-charge Andrew Ibell yesterday said the “heart-wrenching” event had been made worse for the Westcourt family by the boat being still missing.

Sergeant Ibell said it was possible the boat could have sunk but it was likely to have drifted along the shipping channel and may have travelled as far as Cooktown.

“Obviously the family is distressed about the whole thing and they would like to see the boat returned home as soon as possible,” he said.

Cairns Water Police are appealing for boaties in the area to report any sightings of the craft described as 6m long and aluminium with a centre cabin. The hull is painted black, with blue sign-writing and a light coloured cabin.