In addition to this, for any given board volume, doming the decks will drastically reduce flex.
It is trendy for shapers these days to make knowledgeable noises about surfboard flex but the reality is that most of it is bluff.
The flex frequency is also very important, as are the harmonics.
Regarding frequency, although even a high frequency flex or resonance is beneficial, ideally the frequency matches the range of the frequency of weighting and unweighting moves used by the rider. Most surfboards have a very high in the water flex frequency, and the frequency is always much higher in the water than on land.
Harmonics is an interesting aspect of flex and is used by sword makers in order to determine sweet spots on the blade and handle. In my opinion superior harmonics are achieved via mathematically generated curves, as these do not have the anomalies which arbitrary spline based curves inevitably produce.
Here' the Olo of the Sun today, one flexible board ...
Just to clarify in response to a question received today: In discussing flex harmonics I'm not talking about a sound, as the flex harmonics are of a low frequency which is inaudible to the human ear.
What I AM talking about is harmonic nodes ( where the sine curves intersect) and; these do affect performance.
There are at least two main nodes and several secondary ones on my longer boards, these are visible to the naked eye as the low frequency flex pulsates from nose to tail.and back again. . . . . . it is quite remarkable to behold !
Here's a video from Michael 'Tinker' Pearce showing sword harmonics, and the nodes of rotation one of which is known as the centre of percussion. I can show exactly the same phenomenon on my latest surfboard.
Hello Roy,
ReplyDeleteThis is a fascinating subject. Would you be willing to elaborate further on the relationship between harmonic nodes and board performance? Would you mind showing the location of the main nodes on the Olo of the Sun? Are you able to calculate with a fair amount of accuracy where they'd be located, prior to building the board?
It seems to me that the existence of nodes of rotation which will not move as energy transfered onto the board results in a harmonic vibration has tremendous implications, both whether the energy comes from the effort of the rider or the wave itself. A board thus finetuned would, for example, be magical in terms of absorbing energy from water irregularities--especially in big waves--without decreased performance , provided the rider stands at or near the node, right?--just as shock waves going through a sword upon striking would not affect the hand holding it at the blade's lower node of rotation.
Remarkable! This adds true depth of meaning to the expression "sweet spot". What a way to feel the wave!
Regards,
Pablo
PS.: I assume it would be nearly impossible for a harmonic resonance to ever develop.
Hi Pablo, Thankyou for your excellent thoughts, I've replied to you in a new post today. Regards Roy
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