Yeah, you need a solid 15ft at LEAST. I did mine in around 8 or 10, so it wasn't ideal at all. I want to try it in open water or at least 20ft deep.

does cutting a competitor monofin like that make it easier to maneuver?
Nope, not at all. This thing is a beast, the width is what makes it hard to turn in. You can see a few times how close the blade comes to my head. If you're not careful, you can really hurt yourself trying to do this stuff--start small, your body will thank you later.