SYDNEY >> Investigators have blamed the grounding of a coal ship on the Great Barrier Reef partly on a crewman’s fatigue.

The Australian Transport Safety Bureau concluded in a final report released Thursday that a series of mistakes led the Chinese-registered bulk carrier to stray from a shipping lane and hit the reef last April 3.

The ship gouged a scar in the reef that experts say may take 20 years to heal and spilled almost 3 tons of fuel oil into the sea off Queensland state before it was refloated.

The report found that the ship’s first mate had about 2 1/2 hours sleep in the previous 38 hours before the grounding and failed to change the ship’s course when he was supposed to.