How Thick is Safe Ice?

Winters in Southern and Southwestern Ontario can be fickle. I’ve seen years (although not recently) when we were ice fishing on Long Point Bay before New Years. I’ve also seen winters where much of the region had as little as three weeks of safe ice for the whole winter.

This year winter weather arrived on November 15 but a series of heavy snowfalls left lakes and rivers with slushy ice that was well insulated by a thick layer of snow. Then we had the Christmas rain and thaw, just when it was looking like ice was becoming safe, dramatically postponing ice fishing in many lakes and most reservoirs due to fluctuating water levels. The longer term affect of the rain and thaw may not be all that bad. It did reduce the snow cover and allowed the recent cold weather to form much harder and safer ice.

I know people who hop out of bed grab their ice fishing gear and they’re off on the ice with little or no thought to current ice conditions. I look at these people and think to myself, “I hope you’re lucky again today.” You can never anticipate every possible situation but with a little knowledge and forethought you can minimize your risk. And yes, you’re taking a risk every time you venture onto the ice.

So just what is considered “safe ice”? Well, as you have likely already gathered there is no definitive answer and many factors come into play when you consider whether or not to venture out onto a frozen body of water. Here are some of the generally accepted guidelines for ice thickness:

Thickness (cm)---------------Type of Load
5 – 8 cm --------------------One person on foot
10 cm ---------------------Small group (single file)
20 cm ---------------------Snowmobile or ATV
30 cm --------------------Light vehicle

Note: These estimates are based on solid “blue” ice. White, slushy, or honeycombed ice may not be safe at these thicknesses.

My personal preference is to have a good 8-12” of solid ice under my feet. I have fished on as little as 6” but I must admit that I wasn’t particularly comfortable the whole time I was out.

Here are a few more things to take into consideration before heading onto the ice:

• Ice freezes unevenly, especially early in the winter.
• Ice is often thicker closer to shore.
• Currents will affect ice thickness.
• Double the estimates and treat river ice with caution at all times.
• Consider honeycombed ice to be unsafe.
• Double the thicknesses in the above chart if ice is “white” or opaque.
• Snow is an insulator; heavy snow cover can mean unsafe ice and variable thickness.

Take responsibility for your own safety, talk to local bait shop owners, talk with local fishermen, and always proceed with caution. Above all get out and enjoy winters ice fishing bounty in Southern Ontario.

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