tips for gauging ice thickness

I was wondering how everyone decides whether the ice on a pond or lake is thick enough to ski on? In the past I have only gone out on ice when I have seen people ice fishing, but I would like to be able to make the judgement on my own, especially since the ice conditions on 2 nearby bodies of water can vary a lot.



My preliminary plan was to pack a hand drill with a 5'' drill bit , but this seems kind of ridiculous.