When I drilled the hull (#133) just forward of the ballast and slightly above, the thickness ranged from 2.5" down lowest, to a bit more than 1" a foot higher up. I drilled 9 holes and those are the averages. I was surprised how thick the hull is just forward of the ballast, right above the keel's bottom. 2.5" is no exaggeration. In fact it might be a bit more than that.