I am already hearing some reports of folks venturing onto Nebraska ice to drill some holes and catch some fish. Looking ahead at the weather forecast for the next week or so, it looks like our ice-fishing season is upon us or soon will be! With that I want to again blog about ice safety. I LOVE to ice-fish and will be on the ice as soon as possible and stay on the ice as late as possible in the late winter/early spring. I will always tell you that you HAVE to be sure it is safe every time you walk on the ice.
Yes, I have blogged about this before, but I want again to put this information into the “new” blog format, and I have learned there are new readers all the time. Some of you “old” readers have forgotten you even read about this before. Those of you who are regular readers of my blog may be thinking of ignoring this post because it is a “re-run”. Don’t! The review is good for ALL of us. I will probably blog about this every year at the beginning of our ice-fishing season.
Here are some thoughts on ice safety:
Dr. Gordon Giesbrecht of the University of Manitoba is THE EXPERT on cold water survival. I would highly recommend study of any of his materials, he really knows what he is talking about, Dr. Gordon Giesbrecht, University of Manitoba. Here is an excellent video he has done:
Now, I do NOT post that information to scare anyone off the ice; it is very safe, a lot of fun, and some of the best fishing of the year. I have been ice-fishing all my life and do not have any close calls or hair-raising experiences to tell you about. However, I will tell you there have been days when I really, REALLY wanted to get on the ice and fish, I knew I could catch fish, but I had to walk away because it was not safe. Having said that, let me tell you that it takes more than just a couple of days with temperatures below freezing to make safe ice.
Water and Ice
We all know that water freezes at 32 degrees F. Water chemistry can affect the freezing point of water and salt water does not freeze until it is colder than 32 degrees, but most of our freshwaters are going to start to freeze at 32. Remember that water has different densities at different temperatures; water is at its densest or “heaviest” at 39 degrees F. As the water cools below 39 degrees, it actually becomes less dense or “lighter”, and water is at its “lightest” at 32 degrees F. That of course is why ice floats. Now, what I am about to say is going to sound incredibly brilliant, but no body of water can begin to freeze over until it cools below 39 degrees. Keep in mind that bodies of water can have a lot of water and all of that water has to cool before ice can form. When water temps. reach 39 degrees F, then the next “stage” is ice formation. Until water temperatures cool to that point, it does not make any difference how cold it gets; all the water in a water body has to cool before ice can start forming.
Different bodies of water have different heat budgets; there are different volumes of water, different basin configurations, different depths, different basin orientation, different water chemistries, different aquatic communities, different water sources, different water exits, etc., etc., etc. All of those things will influence when a body of water freezes over. Generally, small, shallow bodies of water will freeze, and thaw, faster than larger, deeper bodies of water.
Wind can keep ice from forming and lord knows the wind blows in Nebraska. When the wind blows hard, it can keep ice from forming and it can even break up thin ice that has already formed, but as that wind is blowing, it is cooling the water. When the wind quits blowing and the temperature drops, ice may form quickly, overnight.
Once there is a cap of ice, then it can thicken by adding ice depth either on top of the cap or on the bottom of the cap. Water underneath the surface of the ice can continue to freeze on the bottom of the ice cap making it thicker. But, the thicker the ice becomes, the colder it needs to be to continue to “make ice”. Snow on top of the ice surface will further insulate the ice cap and make it harder for the ice to thicken. However, snow on top of the ice will also weigh the ice cap down, cause it to “sag”, and when that happens water will seep up through cracks and holes in the ice. Water on top of the ice will create slushy conditions by flooding the snow cover, but eventually that slush will also freeze and that is another way the thickness of ice can increase.
Generally, first ice is relatively clear, hard, and will support the maximum weight for its thickness. But, there are times when wind action can break the ice as it freezes and then chunks of ice will eventually refreeze into a cap of ice. Or, snow may be mixed into the ice when it forms creating milky ice. At first ice, any ice that does not appear to be clear and hard could be considerably weaker. Also keep in mind that objects in the water or on top of the water or even shorelines themselves may capture warmth from the sun and ice in those areas may be thinner. Areas of water movement will also have less ice.
This chart is only a guide, there are too many variables to put it into a formula that provides all the answers, but this will give you an idea of how long it takes to make ice:
Generally 3 inches of new, clear ice will support a person safely. However, ice thickness can vary on a body of water and 3 inches of ice leaves little margin for error. Four or more inches of new, clear ice will usually be plenty for safe ice-fishing. Do not forget that new ice is often very slick and ice anglers should plan to wear some type of ice creepers to provide additional traction. Hard falls on top of the ice can also cause injury.
In summary, I know we are all excited to get on the ice, but be patient. Depending on the body of water, and there is a lot of variation from one body of water to another, it will take longer to make safe ice than you might think. Wait for it, it is coming.