Check out the video below of Brisbane racer Jalen Andreatta... You can clearly hear the high pitched hum from the trailing edge (TE) of his fins as he goes past.
Now his board speed was in excess of 30 knots, ranging between 32 and 35 knots over the day (backed up by the GPS on his board)... So it's well above the average speeds you'd find on a racecourse because you A: never get butter flat water like this... and B: you can't run these angles and still be competitive on a windward/leeward course.
But here's the question (for a rainy day) , Without the hum (which is caused by vibrations due to either fin irregularities, TE irregularities, too blunt a TE, or a loose fit in the box) what do you think the difference would have been to his speed?
1% difference? 5% difference? We're not going to know now because we were having too much fun to fix it... But it begs the question whether or not it's an easy way to get a little bit extra speed out of your current setup.
Do your Tectonics T43K fins hum like this too? Every set i've ever tried hummed, in the 42cm and 41cm. But my personal Vector Canefires don't ever even make a peep!
DISCUSS!!!!
No idea on your % difference question as I imagine it would depend on a number of factors - namely, the answer to what the cause of humming for this particular instance is.
On another note, any chance that butter flat location is where the races for sail Brisbane will be held? :)
Not sure about kiting but for windsurfing it doesn't seem to make any difference.
To stop it you get some sandpaper and sand the trailing edge flat (the problem is that the trailing edge of the fin is too rounded leading to vortex shedding).
When I had a select fin that whistled like this it actually made me faster, as it would play distinct 'notes' the faster you went, so you tune by listening to the fin. Worked for me 
... my old Sector 60 OneDesign used to hum, it had 3 different pitches. First one you know your going good, second and your hanging on for grim death and if you get the third humm or squeal, its on and you have some serious speed.
You can hear it on my little video below, the first pitch at 51 seconds into this video:
Thanks Rhys. I've been wondering about this cos since returning from Auckland I've put my old fins in a new board. I haven't bothered to tune the fit or put them in perfectly and they don't humm. They screach. It's verging on painful to the ear at full tilt. I had a sick session on glassy water in 15 knots and it was seriously loud. The faster the louder. The pitch didn't change too much. Like you, I didn't care at the time. Was having too much fun to stop
thats super strange. it only happens on glass fins, hasn't happened on any carbon fins that I know of. I guess it's because they are so stiff.
interesting topic.
