The question of why the Queen of the North sank two years ago after the ferry hit an island off British Columbia's north coast will remain unexplained in a report to be released on Wednesday, CBC News has learned.

bc-080311-queen-north2-ins

The Queen of the North sank in March 2006, after hitting the rocks of Gil Island on B.C.'s north coast. ((Transportation Safety Board) )

The Transportation Safety Board is set to issue its final report into the tragic sinking without explaining why the BC Ferries' crew failed to make a routine course correction and ran the vessel into Gil Island, killing two passengers.

Ever since the vessel went down on March 22, 2006, people have wondered how it could have happened.

But two years later, CBC News has learned that the Transportation Safety Board is "unable to explain" why the two crew members on the bridge failed to steer the ship away from the island.

The report will say merely that Karl Lilgert, the senior officer on the bridge, failed to order a course correction and that the quartermaster Karen Bricker, didn't make that correction.

bc-080311-queenofnorth-ins

An underwater view of the sunken Queen of the North, which ran aground off B.C.'s north coast on March 22, 2006. (Transportation Safety Board)

It doesn't answer the key question of why the two officers didn't realize they were off course.

The Queen of the North travelled the inside passage from Vancouver to Port Hardy and Prince Rupert.

But on the night of the accident, it failed to make a course correction. It proceeded straight for 14 minutes at 17.5 knots until it ran aground off Gil Island.

Of the 101 passengers and crew on board, Shirley Rosette and Gerald Foisy didn't make it to the lifeboats before the ferry sank. Their bodies have never been found.

Minutes before the vessel went down, only two crew members were on the bridge.

They'd previously had an intimate relationship and the Transportation Safety Board says that when they missed the course correction, they were "engaged in a conversation of a personal nature.''

But the report also says the vessel was encountering a rapidly moving squall, so they could have been distracted.

"They weren't sure where they were, they didn't pay attention, if you will, and the result was catastrophic,'' said BC Ferries chief executive officer David Hahn.

While it doesn't explain why vessel sank, the report faults BC Ferries on several points, such as not having a more qualified officer on the bridge.

It also notes a lax atmosphere on board, where, it says, marijuana was smoked by some crew members of the ferry, although it does not say which ones.