*** Official Griffin Surfboards Thread ***

Mr J

Michael Peterson status
Aug 18, 2003
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Regional Vic, Australia
"flow turning" is essentially the same as "wrap"
yes you are right! both are bending water - maybe we just have a terminology mixup. I normally use "wrap" to mean water wrapping the rails and "flow turning" to mean water following/being bent by the hull contour. So if you you mean that water "wrapping the hull" creates lift then I am in agreement with you. I am sticking to my guns that water wrapping the rail creates downforce not lift - but maybe you were not saying that as I originally thought? --> edit I may have contradicted myself with what I wrote below about that! Food for thought.

I did the spoon experiment for you. See how the water "wraps" around the spoon? You can feel this in your hand as it grabs the spoon, moving it to the right.
This "warp" can be thought of as the rail holding in to the face.
Remember, this wrap is a long spiral. If the radius is too tight, the water won't wrap and will release, ending the forces at work.
That experiment is a nice illustration of what I call "flow turning", bend water to the left - force in the opposite direction created to the right.

Its also a nice theory on "hold" - the larger radius rail allows the water to wrap not release - which means rounded soft rails hold better because they get pulled into the face. That's what you are saying isn't it?

Except, its just a "nice theory", the boars I have ridden tell me the exact opposite - the chunky rounded rail boars I have owned seem to have the rail pushed out of the face causing the board to sit more on the surface and feel skatey - less hold (which can be fine for a groveller). My pinched rail boars allow me to penetrate the wave face more with my rail, get more purchase from the hull thus give me more hold. Experience trumps theory.
 
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PRCD

Tom Curren status
Feb 25, 2020
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Except, its just a "nice theory", the boars I have ridden tell me the exact opposite - the chunky rounded rail boars I have owned seem to have the rail pushed out of the face causing the board to sit more on the surface and feel skatey - less hold (which can be fine for a groveller). My pinched rail boars allow me to penetrate the wave face more with my rail, get more purchase from the hull thus give me more hold. Experience trumps theory.
You are able to sink the feathered rails more, thus they hold more. The larger rails have more buoyancy, so they don't sink as much and grip as much. Rail radius/volume and buoyancy are trade-offs.

Try gaining 50 lbs/wear a 50 lb weight vest and report back on the chunky rails.
 
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Mr J

Michael Peterson status
Aug 18, 2003
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Regional Vic, Australia
You are able to sink the feathered rails more, thus they hold more. The larger rails have more buoyancy, so they don't sink as much and grip as much. Rail radius/volume and buoyancy are trade-offs.

Try gaining 50 lbs/wear a 50 lb weight vest and report back on the chunky rails.
Yes, to everything except the 50lb weight loading :) However that's a good point that my stature and ability is going to provide only a limited design experience. This is further compounded by my reluctance to purchase vast quantities of boars (I wouldn't have the time/ability to master them all anyway). This is why I try to listen to the experiences of others who I deem reliable.
 

griffinsurfboard

Duke status
Oct 31, 2004
25,653
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Palm Coast , Florida
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You are able to sink the feathered rails more, thus they hold more. The larger rails have more buoyancy, so they don't sink as much and grip as much. Rail radius/volume and buoyancy are trade-offs.

Try gaining 50 lbs/wear a 50 lb weight vest and report back on the chunky rails.
You want to skate across the wave in control - not sink the rail = stalling
Designed in reduction of area towards the tail enables this in Template and rail foil
 
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Mr J

Michael Peterson status
Aug 18, 2003
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The bottoms ones. The rear Griffin10 sits in a plane that is dead flat, where did I get that idea from :) I don't believe in speed killing V with the area reduction of the round tail.

G10.jpg
 

Mr J

Michael Peterson status
Aug 18, 2003
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Regional Vic, Australia
..Except, its just a "nice theory", the boars I have ridden tell me the exact opposite - the chunky rounded rail boars I have owned seem to have the rail pushed out of the face.. .
Just talking to myself here ... I don't think the spoon experiment theory is wrong. I'm not some 1970s hippie who thinks going surfing is some sort of mystical spiritual experience. I have looked down at my feet and there is some wrap at times - so as n4s said the laws of physics must apply. Therefore there will be some suction (holding force) generated by the wrap, its just that this must be completely cancelled and overridden by some forces in the opposite direction.

As an experiment I raised the rail of my annual build file by 3mm which I know to have a significant performance effect and it produced just half a litre of extra volume and this was spread over two rails. So for only one rail we would be looking at 1/4 litre of volume and not all of that is going to be submerged, plus some of the extra volume finds its way into the deck.. Even if it was that is just 0.25 KG of lift from buoyancy. So the only explanation I can come up with is that the rail is planing at speed i.e deflecting water away and the chunkier rail planes better.
 

maybe

Michael Peterson status
Jul 23, 2011
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Griffy - look at you - your own thread.

I'm guessing this is neat for you to wake up in the morning and see who has commented on "your" thread.

I can't give a penny to a Trump supporter... but you're flush with money, so it doesn't matter.

You ever think about shaping a harder rail on your logs?
Lots of people ripping on single fins and don't need a 5-fin longboard.
 

ajmojave

OTF status
Aug 26, 2018
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LOL says the kook approaching 36K posts on an Internet board.
You are the antithesis of a surfer... as you finger-fvvk your phone all day.
Are you paid to generate content... or should I just punch you in the head when I meet you?
Moderators: why are posts like this allowed?
 
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casa_mugrienta

Duke status
Apr 13, 2008
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Petak Island
LOL says the kook approaching 36K posts on an Internet board.
You are the antithesis of a surfer... as you finger-fvvk your phone all day.
Are you paid to generate content... or should I just punch you in the head when I meet you?

LOL

I surf more than you

I travel more than you.

You're sitting around threatening me with unprovoked violence over your phone - now that is some weird sh!t.

Does that make you a genuine surfer bro?

Never ever seen you in the water and I'm sure I never EVER will.

You're think you're special but you're just another worthless nobody.

You contribute nothing, and nobody here likes you.
 
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