An explanation- of sorts- for the grounding on a charted reef found here:
Higgins said the third mate, who was navigating, and the helmsman, who was steering, were the only people on the bridge at the time of the accident. She said the ship was southbound in the Lynn Canal making a right turn into Icy Strait when the crew saw a problem.
"It's our understanding that they realized that they were not going to be able to successfully navigate that 90 degree turn, so they attempted to make a correction and weren't able to make a correction successfully. So that's when they struck Rocky Island," Higgins said.
NTSB officials could not say why the crew could not make the turn. They said they would be able to piece together a clearer picture of events when they have analyzed the ship's voyage data recorder, a device that is similar to an aircraft's black box.