Fluke design/position questions

[MermaidMama]

Alright so I've seen hundreds of different fluke/monofin shapes in my quest to figure out exactly what I want for my own silicone tail when I start making it, and my question is this, everyone always wants to hide their heels in the shape, usually by adding extra fins, so why are all of the available monofins made to start the blade part lower? Why does the fluke never seem to fan out from higher up, maybe above the heels? Is it that the monofin company's just haven't caught up, do some of you more experienced mermaids think maybe it might make the tail harder to maneuver in or global preference for a longer slimmer looking tail? I know there are people who make their own monofins have any of you ever tried raising the start of the blade and I just didn't see it?

[Nykur]

I think if you raise the start of the blade you might lose some of the propulsion? I think the blade fanning out at the tips of your toe is to ensure as much possible propulsion.. because if you do a dolphin kick for example the 'pulse' ends in your tippy toes :p