They have all kind of sonar on board, not just to see the bottom but to also find subs. They were just not functioning normally, that's all. Having guests on board gets me distracted so I'm sure it does them too, espeically when they are high ranking officers.
What the article seems to suggest is that they ran aground when unloading the guests into a small boat. If that's the case, they must have gotten too close to shore and the current pushed them into lower waters. If that's what happened, I find it hard to believe they couldn't pull them off.
I think the article has errors in it. In any case, you can surely bet the crew is making big-time fun of the captain behind closed doors

I wish I was there to see all that.