Hate to be a naysayer, but as a monofinner I have to say they have no place in hockey. They are for straight lines only, no matter how you make them. The simple fact is that you cannot turn quickly with your legs together, so even if you make the monofin smaller than normal fins, you'd still be at such a disadvantage in general play that you'd be a liability. Even an awesome piece of design like the lunocet wouldn't get around this. I suspect that those wouldn't be legal though