With winter at full swing many outdoor activities require us to voyage out onto frozen lakes, rivers, and ponds. It is important to educate yourself about safe ice practices. The most important thing to remember is that NO ICE IS SAFE ICE.
Whenever voyaging out onto the ice, try not to go out alone, if that is not possible tell somebody where you will be going and the estimated time of your return. Also, there is some essential gear you will want to bring:
Know the body of water that you are looking to go out on
Things like moving water and fountains have a large effect on the formation of ice. If you do not know if there is moving water or spots where thin ice may be. It is smart to refer to maps before you go. Look for inlets and outlets as well as structures. Sometimes it is even better to talk to locals. That may be a guide, outfitter, or local bait shop.
Realistically you cannot accurately tell the thickness of ice just by looking at it. Test the ice before you go out. There are three main ways to check the thickness of ice. These involve the use of three tools.
There are many charts and recommendations for ice thickness and its strength but as stated previously there is no way to be certain that ice thickness will be the same across a body of water. Depending on how the ice froze and the weather conditions, ice of a certain thickness may not be a strong as indicted on charts. The Minnesota Department of Natural Resources gives these recommendation for ice thickness.
For new, clear ice only
Under 4" - STAY OFF
An accepted rate at which ice is formed on a body was developed by George Ashton in 1989 and is based on a unit called freezing degree days (FDDS), and according to Ashton it takes roughly 15 FDDS for an inch of ice to form. FDDS are derived from a simple mathematical equation.
FDDS = 32 – (Average temp. over the past 24hrs)
FDDS= 32 – ((24 hr High temp + 24 hr Low temp) / 2)
FDDS / 15 = inches of ice formed
Example: The high temperature over the last 24 hours was 20 degrees with a low temperature was 10 degrees so.
20 + 10 = 30
30 / 2 = 15
Average 24 hr. temp. = 15 degree
32 – 15 = 17
17 / 15 = 1.13
1.13 inches of ice over the last 24 hours.
Make note that this equation is only to be used when ice is between 1-3” thick. Ice will grow at a slower rate after ice thickens beyond 3”. There are also other factors that go such as cloud cover and wind that may affect this equation.
These charts give a better prediction of ice thickness.
Ranger, writer, reckless