Bill , Ebb I'm sittin here thinking and when I drilled for a new head discharge the hull was 3/8. What I found was VERY inconsistant thickness's. Forward 3/8 just below the waterline ,forward high on the topsides,my anchor locker drain hole 3/8 , aft 5/8 below waterline at the turn or the bilge ,side of keel 3/8-7/16 , and the 1 1/8 at the forward base.???????But back to the original question.....at low speed I still doubt much damage other than paint.