The St. Anthony Falls Laboratory (SAFL) Healthy Waters Initiative conducts robust research on Minnesota’s lakes and rivers. In 2020, with generous community support, SAFL researchers used specialized sensors to characterize the surface waves of various recreational boats. Now, they are preparing to further characterize the propeller wash that is generated by these boats. Make your gift today to support our research and keep Minnesota’s lakes and rivers healthy.
In the fall of 2020, SAFL researchers installed five sensors at differing distances and depths from the shoreline of a Minnesota recreational lake to measure the height, energy, and power of waves generated by non-wakesurf and wakesurf boats. The boats were driven past the sensors under different operating conditions, including slow plowing speeds that yielded large waves, and fast on-plane speeds that yielded smaller waves. The study found that wakesurf boats produced the largest waves under all conditions evaluated, with the overall largest waves generated during slow plowing speeds associated with the sport of wakesurfing. The study also showed that when wakesurf boats operate under their typical wakesurfing conditions, they require greater distances to reduce their wave characteristics to levels equivalent to non-wakesurf boat operating under their typical on-plane conditions. This data can be used to inform boat operational distances necessary to reduce wave height, energy, and power to levels deemed acceptable. Click here for FAQs or to read the full research report.
Building on Phase I’s findings, SAFL researchers will now focus on characterizing propeller wash, which is a general term for the turbulent jet produced by the boat motor and propeller. The propeller wash produced by large recreational boats is powerful, and has the potential to cause mixing of the water column and suspension of inorganic sediment (silts and sands) and organic detritus. Available research on this topic is extremely limited however. Learn more about propeller wash here.
SAFL researchers will explore this topic through a field-based research study that will take place on Minnesota waters. The study will aim to address the following questions: How deep does propeller wash penetrate into the water column for different boat sizes and usage scenarios? At what depth does propeller wash begin to interact with the lake bottom, and what happens when it does?
Bottom mounted current sensors will be deployed in various water depths that will measure water current depths and velocities as the boat traverses over. This data can be used to help inform boat operational depths for various recreational boat types and usages.
Through robust characterization of wake waves and propeller wash, data driven decisions can be made that protect our ability to utilize our prized lakes and rivers, while minimizing boat-generated impacts to lake and river health, public safety, share-use accessibility, and degradation of property.
Your gift today will help ensure that our lakes and rivers can be enjoyed by all for generations to come.
St. Anthony Falls Laboratory would like to thank our lead donors for this phase of our research: the Michigan Lakes and Streams Association, Joe Shneider ($10,000), and Gabriel Jabour/Tonka Bay Marina ($30,000).
Donor name and gift ranges are considered public information under Minnesota law.