The project is probably inspired by [Berto]’s collapsible amphibious e-scooter that used the same electric drill propulsion setup ... but it is a nice bit of MacGyverism to build a boat motor ...

If you plan on drilling into brick, concrete, or stone, you’re going to need to use a masonry drill bit. These specialty bits have strong carbide tips for boring through hard materials ...

You are rubbing a soft stone against keratin ... I read about the Electric Nail File Drill on a Reddit forum for new moms and, unsure it would even work, got the most basic model on Amazon ...