As stated the noise you are experiencing is very common, it is due to a fin trailing edge anomaly and it happens at certain speeds and angles of attack where the non beneficial vortex frequency enters the audible range.
It's a well known well researched phenomenon which is easily cured. Check out the trailing edges of your fins or fin. If there's no damage it is a foiling error. Many fins have a foil section which includes an accelerating curve or 'hook' and sometimes these cause the issue.
Roy you are not qualified to make a diagnosis. Btw who said the noise is caused by an error or a damaged foil? I just don't know where to take this...as far as explaining how ridiculous you are. I have heard this effect on every board that has a camera mounted to capture the sound. So let me ask you, when a jet travels at a high speed and a screaming noise is created - not from the engine, do the wings need to be fixed or is it a phenomenon?
And before you go on embarrassing yourself, I work in industrial prototyping and I'm versed in these areas.
Roy you need to do two things. I've suggested this to you before but here it is again:
1. You need to take a business class
2. You need to take a class on design or an entry level physics class.
You are still in denial over the fin hum/fin issue, the surfboard lift issue and the elementary physics of surfing, just for a start.
Instead of making vague superior sounding noises you should concentrate on physics yourself as you have shown a lack of understanding on all the issues raised so far.
Let's take the surfboard noise issue. You still illogically maintain that I am incorrect in diagnosing probable fin trailing edge issues .... I suggest that you take some sandpaper and correct the trailing edge, it will probably cure the problem.
No Roy this goes back to your mis understanding (I'm being kind to you) of the thruster set up. What I'd like you to do is get yourself a thin stick of decent length. Now swing it through the air at a good speed. I want you to think about why noise was created. You've demonstrated deep misunderstanding of the simple concepts. I'm here to help you. Who knows maybe even help you make a better board.
The amount of lift produced by a foil depends upon at least 5 factors, and it is thus meaningless and hardly a 'play on words' to state that the lift of a double foiled fin ( which is what you are using as your argument against lift being produced by single fins) is 'nothing compared to single foiled fins'.
Single fins are quite capable of producing more lift than other fin setups, it depends upon many factors: area, foil, aspect ratio, speed, angle of attack, chord ratio etc.
So the bottom line is that I am correct and those who have stated here that single fins cannot create lift at all are wrong... there's some careful back pedalling rearguard action going on, but 100% wrong is still 100% wrong.
Roy... you are so caught up in being right, and everyone else being "incorrect," that you can't have a comprehensive discussion about design. Loosen up... just a little. Not everyone here is against you. You know the difference between the lift force created by symmetrically foiled and asymmetrically foiled fins... and how those forces change and compare at varying angles of attack. Why can't you just talk about that? Why confound a very simple principle with at least four more factors, with no context or explanation?
I'm an educator. Here's what we call a "teachable moment." Talk about what you know so others understand. Unless, of course, you don't WANT others to understand. Then just focus on the argument, and not the content of the discussion.
LBCrew, thank you for bringing that post back to my attention. Roy lift on a foil is dependent on 1 factor and 1 factor only.... The difference of pressure between the 2 sides of the same foil. Period, end of story.
Now like I said I just don't know how to explain you other than you're completely lost in your own mind and design prejudice.