The boat was on the second day of a seven-day cruise

Marino Cattiotti was put in charge for four hours because another navigator was ill, the National Transportation Safety Board report said.

More than 200 people were evacuated when the Empress of the North hit a rock 25 miles (40km) from Juneau.

The report called the designation of Mr Cattiotti as navigator "imprudent".

Hull ripped

Mr Cattiotti was fresh out of a maritime academy, the National Transportation Safety Board preliminary report said.

It was his first voyage on the ship.

The report said instructors believed that "placing a recent graduate of the school with no watch experience outside of a training environment, on watch, at night, in pilotage waters, in an unfamiliar vessel, without any additional preparation and/or supervision, was imprudent".

Mr Cattiotti had said he had not taken part in any drills or had any training on the Empress of the North.

The riverboat-style boat was on the second day of a seven-day cruise when it suffered the accident.

The ship's hull was ripped in a number of places and the propeller damaged.

The final report is expected within eight months.

The ship's owner, Majestic America Line, said it could not comment until the investigation was over.

According to Majestic America's website, the 360ft-long (110m) ship has 112 cabins and can carry 223 passengers, as well as 84 crew.