University of Minnesota lab to study size, force of boat wakes

A man wakesurfs behind a boat as passengers watch.
Noah Flegel surfs behind a wakeboat in July 2019 on Lake Minnetonka in Mound, Minn. This fall, University of Minnesota researchers plan to launch a study of wakes created by recreational boats, hoping to provide insight into their impact on Minnesota lakes and shorelines.
Christine T. Nguyen | MPR News 2019

University of Minnesota researchers plan to launch a study this fall of wakes created by recreational boats, hoping to provide insight into their impact on Minnesota lakes and shorelines.

The U of M’s St. Anthony Falls Laboratory plans to measure the height and energy of waves generated by wakesurfing boats and other large watercraft, as well as the turbulence created by propellers, said Jeffrey Marr, the lab’s associate director of engineering and facilities.

The study comes as the popularity of the sport of wakesurfing is on the rise. But so is controversy over the boats that create a massive wake, allowing surfers to cruise along behind them without a tow rope. 

Their large size and powerful motors have raised concerns among some lake advocates, who worry they’re eroding shorelines and disturbing sediment and aquatic plants on the lake bottoms.

The university researchers will use a variety of sensors and cameras above and below the water surface to collect data as they operate a test boat under different conditions, lake depths and distances from shore.

“We think that there may be some interesting attributes about larger waves that are generated by boats,” Marr said. “And when we want to study how those waves interact with sediment and vegetation and habitat, we need to have that data. We need to understand what the velocities and forces are.”

The university sought $420,000 from the state Legislative-Citizen Commission on Minnesota Resources for a three-year study of wake impacts, but the commission didn’t approve the funding.

Instead, the researchers have launched a crowdsourcing campaign, seeking $94,000 for the first year of research. 

“We don’t do that for all of our projects,” Marr said. “But this one just seemed to have enough citizen interest, and other organizations interested in it, that we thought we’d give it a try.”

They’ve had decent success so far, raising more than $58,000 — enough to get started in September, Marr said. He said they’re in the process of selecting a lake for the study.

The data the researchers collect could help inform the policy debate over whether wakesurfing boats should have additional regulations. Bills proposed at the state Legislature this year requiring wake boats to keep at least 200 feet from shore, docks and other lake users didn’t survive the session.

The Water Sports Industry Association, which includes manufacturers of towboats, launched a campaign aimed at getting boaters to "wake responsibly." It encourages boaters to be respectful, keep away from shore and avoid repetitive passes.

The industry maintains that if boats stay at least 200 feet from shore, the waves are substantially reduced by the time they reach shore.

While wake boats have generated headlines recently, Marr said the study won’t focus exclusively on them, but will also include fishing boats, ski boats and pontoons. 

He said this study should provide some preliminary results by early next year, but it won’t answer every question about boats’ effects on sediment, vegetation, fish habitat or aquatic organisms.

“It’s a first step, the characterizing of boats and the energy they put into the water,” he said. “But it’s an important first step, and we think there will be results that will be useful.”