Humming fins

[SaMoSUP]

I've been trying a quad fin setup on my Starboard 7'7 Pro and I get a humming sound when I get on a wave. Any ideas how to fix that?

[surfcowboy]

Man, check if they are mounted well (not loose) then I'd look for nicks or dings.

I've seen it from non or badly foiled fins too like on inflatables. Are they plastic or like good fiberglass fins? If they are cheaper ones you can try just swapping. If they are new and not dinged you might talk to the manufacturer.

Btw inflatable guys putting some trailing foil on your fins will ease or stop this.

[Badger]

My JL Stun Gun hums at high speeds. I'm using Futures GL2 quads. I hadn't concluded that it was the fins causing it. I thought it might be the hull.

I like the sound.

[surfinJ]

I've expierenced it as well with quality fins when going really fast.

It's some sort of cavitation trailing the fin. Probably something a little sandpaper on the trailing edge can fix.

[surfcowboy]

Y'all all surf faster than me.

[newton333]

sand down edges

[madeinsantacruz]

Make yourself a small sanding block and hit the trailing edge of your fins.  Sharpen 'em up and fin hum will stop. 

MISC

[Wetstuff]

Like Badger, I would see it as a sign that the Gods were pleased with your performance. 

Jim

[SaMoSUP]

Here's the quad setup that's humming, FCSII Firewire sides w Performer quad rears. The 2+1 setup I use, with Futures Jamie Mitchell fin in center box, does not hum.

Dumb questions, where exactly is the trailing edge just the back rounded tip or the whole back of the fin and what grit sandpaper to use?

Also wondering if I got the Performer sides if the humming goes away. These fins are not cheap.

[mrbig]

There are two scenarios. Take the fins out and check to see if there is any deviation from flat.  IF there is try to work with a manufacturer for a replacement Had to do that with new FCS II AM fins, one was NOT flat and was replaced.

The other more common issue is a trailing edge that,is not smooth. Wet sand with 600 wet till' it is smooth.

Humming fins are not indicative of anything but a problem!

[DavidJohn]

Make yourself a small sanding block and hit the trailing edge of your fins.  Sharpen 'em up and fin hum will stop. 

MISC

I agree about the light sanding of the edges.. But not about the shapening them bit..

[RATbeachrider]

Which one of the fins is humming? Isolate before sanding all four.  Btw, nice sanding of the paint exposing the carbon underneath.  I've got an old 1995 Becker with glassed on fins and that board has been humming from day one ... I liked it!

[supsurf-tw]

Why do fins hum?
Because they don't know the words.

Seriously, you need to detail the trailing edges. The manufacturers don't like to leave em sharp for safety reasons.

[mrbig]

SaMoSUP, You now know it's the rear fins in the quad setup. Check 'em on a really flat surface to make sure they are flat! If not get a replacement for the one that is not true. Does it hum more when turning to a particular side?

If they pass the true flat test, sand away. I was told a long, long time ago to actually take the sharp edge off a little if they hum..And that's why you use wet  600 - it's a subtle  change to remove any manufacturing gremlin rather than making ginsu knives!

[Badger]

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