I'm not a boating expert (or novice) but the tarp is on the upper part of the boat and "the damage was above the waterline"

How does one strike a rock with the deck of the boat? I just can't picture the deck going into the sea and hitting a rock without also damaging the lower part of the ship. <img src="http://www.traveltalkonline.com/forums/images/graemlins/titanic.gif" alt="" />