Discussing Roy's surfboard designs.

Some people say that I always surf bad waves, others say I only surf good waves.

Lol

 

You are not making sense... you are attributing the fact that single fins do not lift in a vertical direction against the hull ( which is true provided that they are installed vertically and do not flex) to double foiling, but it is just as true if a single is single foiled. It's actually due to the vertical orientation of the fin not the foil symmetry.

You also ignore the fact that all fins create lift and that a major and useful component of this lift is horizontal in relation to the board. Lift in both these planes can and is used to drive the board via the muscular action of the rider, and is used for other purposes.

In spite of the careful retrospective revision of your position you are still getting it wrong.

Those who have stated categorically that my boards do not create lift are absolutely deluded, but experience shows that such people do not care about whether or not they are correct as long as they can attract a group willing to make the same noise as they are.

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Why are you posting statements which even you must know are false?

 

I'm not the only 'voice'.

My boards will probably last longer than I will as they are very durable, as are the designs.

 

The opinion of the majority is irrelevant as a design consideration, so I disagree.

No, I'm simply correcting misinformation.

Of course weight redistribution happens constantly, because the boards are so well balanced this redistribution does not require excessive and inefficient board walking, or the celebration of that walking which becomes a design trap or loop.

The premise that I don't redistribute weight is incorrect and so is the conclusion.

Increases in speed can also require moving aft in order to reduce planing area.. it is not as simple as you make out, and the myth that nose riding is a move for speed is just that... and the error is related to increases in wetted surface and subsequent drag area overcoming the drag advantage of a low angle of attack

That is usually due to a fin foiling error.

Absolutely incorrect on both counts.

All surfboards plane at surfing speeds, and lift ( presumably you are now referring to vertical lift which takes load off the hull rather than horizontal lift, please specify what lift you are referring to in future) is produced in my boards via dynamic planing lift from the hull, buoyant lift via displacement and lift from the fin(s) in the case of my tunnel finned boards and those with canted side fins.

 

It's a common phenomenon which I and many others have experienced at times, it is speed specific and is due to a non beneficial vortex being set up by the fin, this causes a vibration which enters the audible frequency range at certain speeds.

It's quite an interesting speed indicator, but does reduce efficiency slightly.

The error is usually at the trailing edge, it could be a slight dent or nick, or a 'hook' in the foiling at the trailing edge.

I had a load example of it on the 'Duke' 9'3" recently, it wasn't a fin foiling error as such it was due to the angle of the cutaway on the D fin at certain speeds and angles of trim. Lowering the nose trim cured it, in future I'm going to adjust the angle of the cutaway slightly to cure it.

By the way when a hollow wooden board gets fin whine or hum, it is amplified a lot as the board acts as a speaker.

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By the way people on threads like this often become over confident in spite of being wrong, due to the feeling that 'everyone' agrees with them.. this is because there's usually a small group of vocal supporters of the misinformation.

What they don't realise is that many people are watching but not posting and that some of those viewers have a better understanding of what is being discussed, these people frequently contact me via PM or email ... so don't think that you are winning.. after all most of what you are posting is false and the consensus which you perceive is largely an illusion... and even if it exists is irrelevant anyway, in terms of truth at least.

It's not a popularity contest it is a surfboard design discussion.

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Did you read the info regarding the fin noise?

It's most likely a trailing edge foiling error ( very common) or a damaged trailing edge.

 

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.


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Get a second opinion if you like, it's a trailing edge error most likely, and a very common one at that.

http://www.surffcs.com/us/technology/fins/faq.aspx

http://groups.yahoo.com/group/wood_surfboards/message/1081

http://forum.surfermag.com/forum/showflat.php?Cat=0&Number=1441256

http://www.gasfins.com/html/useful_tips.html

http://www.surfingsandiego.com/forum/forum_posts.asp?TID=4230

http://www.iwindsurf.com/forums/viewtopic.php?p=201365&sid=5119af52286426b9058cc095ba325e5c

http://www.futuresfins.com/school-faq.php

http://www.roystuart.biz/2010/12/surfboard-fin-guide-part-3-dreaded-flat.html

 

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.