The ice is never the same thickness all over. Six inches of good solid ice in one part of the lake does not mean that somewhere else on the lake there won't be thin unsafe ice, or even open water. Early and late season ice requires extra caution. Early season ice is not fully formed on the entire lake. Pressure ridges can appear over night, often in areas that were sailable in previous days.
Ducks can keep large areas of the lake open even after long periods of freezing temperatures.
I've always thought that racing is safer than pleasure sailing because the club has looked over the sailing area and picked out the best ice on which to race. A smooth surface, thick enough ice, no large cracks, no open water, are just a few of the things that the club looks for before we set up the marks. We also have the clubs safety equipment, and the ATV emergency vehicle keeping track of the boats which are racing. Sure, the club will come to the aid of anyone who needs it, but on a lake the size of Mendota we may not even be aware of the need for assistance in areas far away from the race course. 5.Talk to others on the lake.