I know a lot of people go out on 3 or 4 inches, but I don't feel comfortable going more than 20 feet from shore when it's like that. I plan on 1/2 the ice that I find when I drill a hole until it gets really thick. Just because there are 3 inches in one spot doesn't mean that it's not an inch and a half somewhere else. If I measure 6 or 7, then I figure even if I walk over a thin spot, it should be enough to hold me.