High Wave Action on the Great Lakes
Dangerous currents aren't the only hazards swimmers face when swimming in the Great Lakes
Waves on the Grand Marais, MI shoreline (Alger, MI). Picture from NWS Marquette
The Dangers of Swimming in Great Lakes Waves
A quick review of Great Lakes fatality and rescue incidents shows a common factor: High waves with a short wave period. Waves on the Great Lakes are different from the ocean because they are strictly wind driven (whereas the ocean contains both wind driven and far travelling waves-or swell). As a result, they typically have a much shorter Period, or length of time in between each successive wave. This means swimmers have less time to recover from a wave before the next wave hits! The data collected on Great Lakes current related incidents showed that most current-related incidents occurred when wave periods were between 2 and 5 seconds (figure 2).
Figure 1 shows that during the years of 2002-2012 where data during current-related incidents was archived, 68% of the incidents happened during moderate to high waves! This also brings an important point to light: Dangerous currents are most often present during high wave situations.
Figure 1: 68% of the current-related incidents occurred during moderate to high wave heights (Data from the GLCID, 2012).
Figure 2: Wave Periods observed during current-related incidents. Most of the rescues and drownings
occurred at times when the wave period was between 2 and 5 seconds (GLCID, 2012)
This data implies that swimming during times of high waves presents several risks:
1. Waves are generally over the swimmers head or at least high enough to cause a struggle
2. Waves are coming into shore in rapid succession-generally with less than 5 seconds in between waves! This can easily tire a swimmer
3. Dangerous currents, such as rip currents, longshore currents, and structural currents are typically present during these scenarios
Swimming in a combination of waves and dangerous currents is not worth risking your life!
WHEN IN DOUBT, DON'T GO OUT!