?other reasons for fin hum ??

okay so thick leading edge

uneven foiling

thick trailing edge

thick fin tip

askew placement ?

twist ?

?uneven base ?

 

 ...i have used double foiled wood

 

thin thin fibreglass

 

  hemp

 

carbon fibre

 

kevlar

 

foam core

 

and

 

commercial fcs 'G10 ' and fibreglass and polycarbonate  fins

 

 in moonies 6'6 x 22 " walden quad / 5 fin option

 

  and they ALL hum ...

 

  the plugs in this board are further apart and further up than i have seen before

 

  could THIS be causing the hum with the different fins i have tried after the last four months , i wonder ??

 

  cheers !

 

  ben

 

...from what i can see , all the fins are toed and canted pretty much the same ....

 

one that I know of is

 

if the trailing edge has a bead of resin along the side, it will humm like a muther

usualy gets there from a gloss coat

drag a razor blade along it to scrape it down, or sand it

this may be what you mean by "a thick trailing edge"

 

you may just need to beat it into submision,,, LOL

edit  I just finnished reading the whole thing,,,,,, maybe loose or just plane shitty fins

Chip, Post a pic close enough where I can see three parts of the fin. 1.)Leading Edge 2.) trailing edge 3.) side profile where I can see leading and trailing edge. Mahalo, Larry

hi Larry !!!

xxoo

 

[quote="$1"]

hi Larry !!!

xxoo

 

[/quote]

 

Hi Buddy, Hope all is well (-;

life is good

got a thrusterset with boxs from foam ez

install went flawless

when I get home (in bakersfield for work) I will post pics

board is nice blue.black and clear swirl

it only hums because it doesn't know the words...

Chip, don't you hum when your happy?

 

I've been known to sing johnny cash songs when longboarding.....

 

:)

 

on a mroe serious note, are the noisy offenders glossed/shiny or lightly sanded?

 

 

If I could only get my fin to hum the tunes I like …

It won't humm if it's limp?  Try soft fin's to think of ugly chicks.

humming usually is not the result of a defect.

all structures vibrate, but not all structures vibrate in the audible range.  Buildings vibrate at about 0.1 - 1 Hz.  You can see it, but you can’t hear it.  The lowest frequency you can hear is 20Hz, but with all the low frequency noise of the breaking waves, you probably can only notice/hear vibrations greater than 200 Hz while surfing.

Since fins have little mass and are relatively stiff, the vibration frequency is fast, or audible, or high pitched.  Massive objects and flexible objects vibrate slowly so that you can’t hear them.

Fins will resonate at a certain velocity.  Sometimes the resonate frequency is beyond the velocity that you could ever achieve, 50 mph for instance.  You think that your fins don’t hum, but really you just haven’t achieved and sustained the right speed.  I have a fin that hums at what seems like 15mph.  I use at as a cue that I have enough speed to launch!  Bzzzzzzzzzzzzzzzzzzzzzzz…3…2…1 and lift off!

thank you for your feedback guys

 

  larry , i am presently woithout a camera , but i hope that when simon arrives on sunday [here for twelve days] , that i may be able to take some with his camera ??

 

  to give you an idea though , the fcs M3's , M5's , and G4s have all hummed ......

 

  ben , that's a good NAME you got there mate

 

  cheers !

 

  [you guessed it!]

 

   ben

 

and...  keep up the lateral thinking resinhead ! yeehaaa!

Chip,

My 3 fins at 18" and 9".  Side fins 8-9" from stringer. Toe 2"-3" off the nose

=> I don’t think fins further forward and further apart are issues.

[ Is it too lame to suggest they don’t know the words?]

Red

[quote="$1"]

humming usually is not the result of a defect.

all structures vibrate, but not all structures vibrate in the audible range.  Buildings vibrate at about 0.1 - 1 Hz.  You can see it, but you can't hear it.  The lowest frequency you can hear is 20Hz, but with all the low frequency noise of the breaking waves, you probably can only notice/hear vibrations greater than 200 Hz while surfing.

Since fins have little mass and are relatively stiff, the vibration frequency is fast, or audible, or high pitched.  Massive objects and flexible objects vibrate slowly so that you can't hear them.

Fins will resonate at a certain velocity.  Sometimes the resonate frequency is beyond the velocity that you could ever achieve, 50 mph for instance.  You think that your fins don't hum, but really you just haven't achieved and sustained the right speed.  I have a fin that hums at what seems like 15mph.  I use at as a cue that I have enough speed to launch!  Bzzzzzzzzzzzzzzzzzzzzzzz....3...2...1 and lift off!

[/quote]

Hello Ben ChipFin ,

I'm with Ben T on this one...I've got this board I really like....Built by a Pro with glass ons....Backside head high it sings...frontside overhead nice tune...I love the song but I'm not very good in bigger surf......:)

All my fin hums have been “blue notes,”…:frowning:

Since no one’s really given you a straight answer yet … it’s usually the trailing edge.  Sharpen it a little and you’ll most likely fix the problem.

I have had two boards with fcs fins that had hum  and then the same fins had no hum when put on other boards.

One board was kind of an embarrassing with a very loud squeal and the other only did it in top gear.

my fins hum at i'm guessing low speeds , [since i'm riding small gutless beachbreaks at present ] , going on what the other ben said earlier

 

  fin hum at low speeds ....is that not strange ??

 

thanks greg , i thought the same , originally ....but, all the fcs fins of mine that have hummed have very thin and sharp trailing edges , unfortunately ......

 

 but,  the more ideas are thrown into the mix here , by a process of elimination / ?illumination? , hopefully we might be able to hit on a solution ?

 

  otherwise , i suppose we all will have to get used to occassionally riding a set of humming fins ?? ....i just feel as though the board / fins are going slower / ?slowing down the board??  when there is humming happening , does anyone else feel / experience this or is it just me ??

 

  i need to add that i am using these different fins that hum , in both commercial board's [eg: moonie's walden , and my island and cooloola and gunteher rohn boards , as well as my home made stub , and fish , and singley

 

  so , i guess it's the fins more than the boards , or the plug distances not being an issue as red boards thought ....

 

  please keep the feedback coming guys , perhaps we can monitor here WHICH of the fcs and other commercial fins hum more than others / what boards they were used in , and [?possibly?] how fast were we going at the time of humming [not to make this a gps thread though , please ?!]

 

   it would be nice to get to the bottom of this ....[otherwise it could end up a hull of a problem eh ?]

 

  cheers

 

   ben 

 

******edit ...

 

  it just struck me ...

 

  how many of you out there riding boards with GLASSED ON  fins also experience fin hum / speed loss ?? ****  [ie: perhaps it is the base of fin flexing where it meets PLUGS problem , which contributes to the 'hum' ??]

I use sandpaper wet or dry, sand front or back edges, fin edges should have feathering curve, go surf and hear, if hum leaves, if not sand more, hopefully the hum silents

The second choice is to soften the leading edge.  I’d give that a go and see what happens.