It occurred to me last night... maybe it's not my fin making that whistling noise.

Perhaps it is the resonant frequency of the metal work in my ankle? :roll:

Mike

I still think it is the same principle as blowing over the top of a beer bottle

As you are travelling through the air "at such speed", perhaps your ears (or another orifice) is creating the whistling sound.

As an experiment, try keeping all your orifices closed whilst sailing - however hard that migh be!

Whatever the reason, the noise indicates wasted energy which in turn means you could go faster, which ultimately shows you are not trying hard enough.

Just as I suspected, you are lazy!!

It's a fair cop. I'll make sure that I try harder next time.