Some areas on frozen bodies of water are specially designed for winter activities, but quite apart from these, it is advisable not to venture out onto a frozen body of water without knowing how thick the ice is. A small number of skating rinks are equipped with signs that must be carefully observed. For example, there is a system of flags, with green indicating that the ice is safe for the public; yellow indicating that the ice is bumpy and that caution is called for; and red indicating that the ice is off limits.
If there are no signs posted, certain characteristics of the body of water, the weather and the environment can help indicate the thickness of the ice.
There are methods for calculating the resistance of the ice, but they involve rather elaborate techniques that would be difficult for sports enthusiasts to apply, such as taking samples of the ice and calculating its thickness. Those responsible for overseeing frozen surfaces can obtain information on these techniques from the Bureau de normalisation du Québec. As for winter sports enthusiasts, they should be especially careful and, in particular, avoid the following:
- outlet streams that bring rainwater to the river
- the outer sides of major bends in a river
- tributaries or effluents
- any obstacle, such as a rock, a tree trunk
- anywhere the speed of the water is variable
- anywhere the ice cover is not continuous
- anywhere the water is heated
- close to a waterfall or a hydraulic installation
- close to a bridge, a dock, a pier or other major obstacles
In addition, cracks in the ice, especially when they are wet and parallel to the bank or shore, indicate a complete break in the ice cover, and are therefore an obvious danger.
Moreover, certain weather factors can influence the resistance of the ice and should be a warning not to venture out. These factors include drops in temperature of more than 10°C between average daytime temperatures for two days in a row, temperatures above -4°C that last more than a day, and heavy snowfall that overloads the ice surface.
If you know the thickness of the ice, it is useful to know that when it is less than 15 cm thick, you should not drive a motor vehicle on it, including a snowmobile. When it is no more than 10 cm thick, even walking on the ice is not recommended.
Lastly, the best way to avoid a catastrophe is to resist the temptation of walking on a frozen body of water. However, if you must cross over to the other side, pay attention to the signs listed above, do not venture out alone onto the ice, stay within at least 15 m of your friends and make sure you each have a rope.
Although we have not provided details about specific rescue techniques, these basic precautions will at least allow you to get out of a tight spot whether you are skidooing, skiing, skating, snowshoeing or hiking.
Source of original French text: Sylvie Turner, Service de la normalisation. From Le Sécuritaire, Régie de la sécurité dans les sports du Québec. 10:1. April-May 1991.