Wakeboarding is big right now and those wave vanes are on a lot of newer boats. Generally they are designed in such as way there is reasonably safe clearance on the stern from the swim platform or stern from the prop, but wake surfers get awfully close to the rear of the boat and people using those boats get used to and complacent with people being on the stern or just behind the boat while in normal operation. An inexperienced helmsman or someone falling on the controls and inadvertent reverse is all it might take. Gotta be careful out there. I feel for those involved.