Dangerous Breaking Waves Threaten Great Lakes Boaters
By Stephen Wittman
MADISON, Wis. (6/29/00) — Boaters should watch out this summer and fall for dangerous breaking wave conditions in the approaches to Great Lakes harbors and their entrances, according to University of Wisconsin Sea Grant Coastal Engineer Philip Keillor.
“Due to the lakes’ low levels, breaking waves are more likely to occur in these areas because the water is shallower than usual. A small boat approaching a Green Bay harbor or marina entrance with a water depth of eight feet, for example, may encounter breaking waves five to seven feet high, which is enough to threaten a safe arrival,” Keillor said. “A boat approaching a harbor on Lake Michigan with a water depth of 12 feet in the approach and entrance channel may encounter breaking waves as high as seven to 10 feet.”
Early this spring, a commercial fishing boat entering the harbor at Two Rivers, Wis., was swung sidewise and almost swept into the entrance structure when it ran into a zone of breakers that had formed near the harbor entrance. According to Chief Mark Barker of the U.S. Coast Guard Station in Two Rivers, the fishing boat was passing through an area that shoaled from 17 feet to nine feet and had breaking waves probably six to eight feet high. The Two Rivers harbor entrance has an authorized depth of 18 feet, according to National Oceanic and Atmospheric Administration navigation charts.
Only quick action by the fishing boat’s pilot averted a disaster at Two Rivers. A less experienced recreational boat operator could be easily overwhelmed in such a situation, Keillor said, with the breaking waves rolling the boat over and its occupants being drowned immediately or thrown into the water to struggle for their lives in the surf.
Even if breaking waves are not evident when leaving a harbor, he said, boaters should be wary of a rise in wind speed, which can raise wave heights significantly in a short time and make the return trip through the harbor entrance hazardous.
“If caught out in such a situation, boaters should call ahead to the harbormaster, local U.S. Coast Guard station or other boaters in the harbor to learn if there are breaking waves in the harbor entrance,” Keillor said. “If dangerous breakers block your return to the harbor, wait for the wind to die down and the waves to decrease to safe heights, or go to the nearest harbor with a deeper approach and entrance or one where breaking wave conditions are not being observed.”
The surest way boaters can avoid such dangers, he said, is to be prudent: “Don’t ever go out on the Great Lakes when the water is very rough.”
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For More Information:
Philip Keillor, Coastal Engineering Advisory Services Specialist, (608) 263-5133Conceived in 1966, Sea Grant is a national network of 30 university-based programs of research, outreach and education dedicated to the protection and sustainable use of the United States' coastal, ocean and Great Lakes resources. The National Sea Grant Network is a partnership of participating coastal states, private industry and the National Sea Grant College Program , National Oceanic & Atmospheric Administration , U.S. Department of Commerce. The University of Wisconsin Sea Grant College Program is administered by the Sea Grant Institute on the UW-Madison campus in Madison, Wisconsin.
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last updated 29 June 2000
posted 29 June 2000 by Wittman
http://www.seagrant.wisc.edu/communications/news_releases/20000/waves.htm
