Blog - The Raven Speaks
Determining Ice Strength 101
January 12, 2012
“How can I determine if the ice is thick enough for me to safety operate on?” This is one of the most common questions we get from our clients. However, the question you should be asking is “How can I determine if the ice is STRONG enough for me to safely operate on?”
The reality is you cannot judge ice strength on appearance or thickness alone. A number of factors should be considered when you are evaluating the risk associated with stepping out on the ice.
Here are a few tips to assist you in determining ice strength and minimizing your risk while working on frozen lakes, ponds, rivers and pack ice:
- Clear ice (or blue/black) is the strongest type of ice. This usually forms to the bottom of existing ice. Snow (white) ice should be considered up to 50% weaker than clear ice of the same thickness. Often you will have mixed or layered ice layers where you have a snow ice on top of clear ice.
- As a general rule, river ice should be considered 15% weaker than lake ice, and will have less uniform thickness.
- All ice thickness guidelines refer to water-supported, clear ice. You should have 10cm of clear ice for one person to safely operate on. Remember that, depending on the type of ice, it can be very thick without any load bearing capability at all.
- Be cautious when working around a shoreline as you may find weaker ice due to shifting, expansion and reflected sunlight.
- Objects such as logs or rocks which are frozen into the ice can absorb heat and cause cracking, expansion or slow ice formation.
- Watch for signs of fluctuating water levels. Dropping water levels weaken the ice by removing the support of the water directly below the ice.
- Large temperature fluctuations lead to thermal expansion or constriction which can lead to the development of pressure ridges or cracks.
- Anywhere with increased circulation of water, such as river confluences or narrows, will typically have thinner and weaker ice.
- Don’t forget ... and these seems so simple: IF SOMEONE HAS FALLEN THROUGH - YOU KNOW THE ICE IS UNSAFE! Don’t be the next victim. Know how to rescue others safely!
- And finally (... wait for it, you know it’s coming ...) nothing but comprehensive, hands-on training will prepare you to work safely, self rescue and rescue others on frozen lakes, ponds and pack ice!
comment to this post.
