Not the rocks fault. It was the same scenario for us. We sailed through at High tide, which covers this unmarked rock(referred to as Goose Rocks in the article, a nearby larger rock that doesn't cover).

I was piloting on a chart, carelessly, and thought I was clear. Our centerboard, drawing 8', was levered upward by the rock, the linkage bound up inside the trunk-the trunk was pushed up off the keel and like a battering ram- and punched through the cabintop. With a foot sized hole below the waterline, we immediately started to sink and took our only option, to drive the boat up on a nearby rocky island(old story).

The 70' Archangel, yesterday, had a slightly different outcome. She draws 8 to 10 feet so the rock skewered her in place with such force, the mast fell. It sounds like she could be saved if she can get to Wayfarers travel lift today. I remember breathing a huge sigh of relief, after a night of jury rigged repairs, when Xmas was finally in those slings.

Here's the article in local Penbay Pilot. My family refers to this rock as "Devils Rock" If you have chart ware, it's the lone rock to the north of Goose Rocks, "obstruction that covers",....

http://www.penbaypilot.com/article/coast-guard-wayfarer-marine-respond-sailboat-aground-lasell-island/18669