The absolute safest rule to follow when it comes to operating on frozen bodies of water is this... DON'T. You can never guarantee that the ice is safe, or thick enough to support the weight of you and your sled (or the weight of your group of sleds!).
Basically, don't venture onto frozen lakes or rivers if it’s possible to avoid them, or unless you can be absolutely sure that the ice will be safe to cross.
EVALUATING THE ICE
It's critical to evaluate the condition of ice before traveling out onto it. This means identifying the quality of the ice and the type of the ice. To evaluate the quality of the ice, you'll need to get a good vantage point. Look for an elevated area such as a hill with a good view of the lake or river and look for the following factors that identify the ice as UNSAFE:
- Slushy, soft-looking ice.
- Ice on or near moving water (i.e. rivers, current or channels).
- Ice that has recently thawed and refrozen.
- Layered or “rotten” ice, which results from sudden temperature changes.
- Fresh snow on the ice that may be blanketing hazards. A layer of snow on the ice can also act as an insulating blanket, causing the ice to thaw or be thinner in certain areas.
- Pressure ridges or cracks in the ice caused by wind, current or ice pressure (it can be extremely hazardous if your snowmobile strikes one of these ridges or if the ice cracks unexpectedly).