I have a patented design for a paddle system that allows the user to propel a paddle board using the upper body technique of cross country skiing. The user can also sit down and row facing forward. The sliding track which attaches to or can be built into a paddle board may also have applications in other industries due to its design for low friction between two sliding components without bearings. Have a look the Supski on my website: https://www.supski.com/ and the sliding track: https://www.quadrailtrack.com/