Soon after freeze-up, the ice sheets on lakes can be heard cracking, thundering and rumbling. These loud, long roars and rolls don’t necessarily mean that the ice is unsafe for walking, but the eerie sounds remind us to respect the ice. Once water turns to ice, it expands and contracts with the changing temperatures, causing these ominous booms.
It takes at least 4 inches of new, solid ice in contact with stationary water for safe skating and ice fishing. A snowmobile requires 6 inches of ice; 8 to 12 inches are needed for a car or small truck, and 12 to 15 inches for a medium-size pickup. Test the thickness of the ice first, and as you do, remember that ice seldom freezes or thaws at a uniform rate. It can be 1 foot thick in one spot and 1 inch thick just 10 feet away.
You don’t want to fall through ice. Cold water saps body heat 25 times faster than air of the same temperature. In 32-degree water, a person will last about 15 minutes before losing consciousness.
If you should break through the ice, the first thing to do is grasp the edge of the ice, as lightly as you can, to support yourself while kicking your feet to keep your body as flat as possible. Crawl forward on the ice on your belly until your hips are at the edge of the hole, then quickly roll sideways, away from the opening. Once you’re on safe ice, get to a shelter to warm yourself immediately.
To help rescue someone who has broken through the ice, lie flat on the ice and push a plank, ladder, pole or tree branch within reach of the victim, or throw a rope or article of clothing. Then hang on to one end, careful not to let the victim pull you into the ice hole.
Jim Gilbert’s Nature Notes are heard on WCCO Radio at 7:15 a.m. Sundays. His observations have been part of the Minnesota Weatherguide Environment Calendars since 1977, and he is the author of five books on nature in Minnesota. He taught and worked as a naturalist for 50 years.