*** Official Griffin Surfboards Thread ***

One-Off

Tom Curren status
Jul 28, 2005
11,201
6,054
113
33.8N - 118.4W
Can we see a pic of the rail curve with your hand wrapped around it (thumb and forefinger)?


Also, when I rode his flat 5 fin, I had a Maurice Cole at the time (massive concave). I told Greg that they both felt similar (couldn't feel the difference). More than one way to accomplish similar goal.
You talking to me?

If so, no can do. Board is in the bag-
IMG_6623.JPG
 

One-Off

Tom Curren status
Jul 28, 2005
11,201
6,054
113
33.8N - 118.4W
how'd it turn out?
Skin went on perfectly. I finally learned after almost 20 years of vaccum bagging, to put the breather cloth on the side opposite the skin I'm attaching. That way I can see all the bumps and bubbles. There would have been two bubbles related to the grain (one on each side, bookmatched) that I could nurseas the resin set (when the resin got really sticky I could press them down).

I normally like lighter woods, but this walnut was a deal. Usually the leaves are 9 to 12 feet long and so you're always paying for an extra 12 feet of veneer (4 leaves per board). But these leaves were just over 6 feet so I paid no extra.

I'm afraid the board is going to be about 1.5 pounds heavier due to using a stringered polyurethane blank vs a stringerless 1.5 lb EPS....

The whole time I'm thinking about some of Greg's ideas.

I remember Oneula talking about how Greg had him run his hands down the rail the see what rolling the edge in the tail felt like as opposed to how having a pure squared rail produces two competing outlines...I lightly rolled the edge in the back.

Greg saying how the flat bottom release after the rocker apex as opposed to a concave. I was wondering why he never(?) put vee in the tail (maybe he did?) because as I flet the board it seemed the vee after the fins would increase the release/low pressure.

Someone should collect all his design teachings and make a book, or at least a thread...

ps his fins will become like the work of a famous artist...now a limited supply, they will increase in value over time...
 
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000

Duke status
Feb 20, 2003
24,484
4,287
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So, in interest of keeping the GG shapes convo alive... what did GG feel about convex bottoms. Not V's, like described above, but full rolled hulls?

:shrug:

Single fins, of course.
i recall him saying hes done lots of bottoms but is convinced flat is the best, fastest planing, easiest releasing, most predictable responding bottom of all

my surfing and boards got better when concaves came into fashion, but since greg, ive been contemplating flat bottoms again.
i think for flatter waves theyre probably better
 
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misterhat

Billy Hamilton status
Dec 21, 2007
1,622
51
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I still have the 5'8" 5 fin modfish I bought from the 2008(?) AB3 event. I lost the fins in several moves, but thankfully I ordered a new set in 2019. It's the easiest board to generate speed I've ever had.

I always wanted to order another board from him but never got around to it.

If anyone has a 5'6"-5'8" 5 fin modfish they'd like to get rid of please let me know.
 

One-Off

Tom Curren status
Jul 28, 2005
11,201
6,054
113
33.8N - 118.4W
I still have the 5'8" 5 fin modfish I bought from the 2008(?) AB3 event. I lost the fins in several moves, but thankfully I ordered a new set in 2019. It's the easiest board to generate speed I've ever had.

I always wanted to order another board from him but never got around to it.

If anyone has a 5'6"-5'8" 5 fin modfish they'd like to get rid of please let me know.
The bidding wars begin...
 

Mr J

Michael Peterson status
Aug 18, 2003
1,911
1,132
113
Regional Vic, Australia
... Greg saying how the flat bottom release after the rocker apex as opposed to a concave. I was wondering why he never(?) put vee in the tail (maybe he did?) because as I flet the board it seemed the vee after the fins would increase the release/low pressure.
... .
You have the correct interpretation of what Greg meant by "release". He used to confuse me for a while because "release" is normally refers to the point at which water leaves the planing surface as it fails to turn a corner - either right at a hard edge or after partially wrapping a softer curve. We also use the term for breaking the rear fin out of its holding track during a tight turn - I think we are stalling the fin with the angle of attack reaching the point that the low pressure surface loses its laminar flow and becomes turbulent - which means we lose nearly all the hold from the low pressure surface.

What Greg meant by release I would call "pressure relief". The hull surface should fall away from the diagonally placed straight edge. He demonstrated that this curve away from the diagonal straight edge could be achieved with tail rocker alone. If we look at the many rocker shots he posts (all taken from a consistent angle) his tail rocker looks sort of staged. Not some clear point at which the tail rocker has accelerated bend, but more bend in the tail. Therefore his tail section was indeed flat I believe.

An advantage I can see with Greg's approach Vs vee is that water will have to travel up and over the stringer line ridge on a vee bottom with unequal pressure each side of the stringer - more drag. Whereas the GG water flow line would have an unhindered and even fall away from the diagonal straight line.
 
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One-Off

Tom Curren status
Jul 28, 2005
11,201
6,054
113
33.8N - 118.4W
We also use the term for breaking the rear fin out of its holding track during a tight turn - I think we are stalling the fin with the angle of attack reaching the point that the low pressure surface loses its laminar flow and becomes turbulent - which means we lose nearly all the hold from the low pressure surface.
Canards baby, canards!

What Greg meant by release I would call "pressure relief". The hull surface should fall away from the diagonally placed straight edge. He demonstrated that this curve away from the diagonal straight edge could be achieved with tail rocker alone. If we look at the many rocker shots he posts (all taken from a consistent angle) his tail rocker looks sort of staged. Not some clear point at which the tail rocker has accelerated bend, but more bend in the tail. Therefore his tail section was indeed flat I believe.
I think Greg might have said something about rocker, area reduction due to plan shape and fins all working synergistically. or something to that effect

An advantage I can see with Greg's approach Vs vee is that water will have to travel up and over the stringer line ridge on a vee bottom with unequal pressure each side of the stringer - more drag. Whereas the GG water flow line would have an unhindered and even fall away from the diagonal straight line.
That's assuming water is moving across the stringer. In those underwater shots the water over the stringer was going pretty parallel to the stringer. I rewatched the video too. The streamers on the stringer almost never veer away from straight. And what's missing from this photo and the video is the section after the fins, which is where I (and a lot of shapers) put my vee.

Screen Shot 2022-07-26 at 7.35.22 PM.png
 
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Mr J

Michael Peterson status
Aug 18, 2003
1,911
1,132
113
Regional Vic, Australia
Canards baby, canards!
...
That's for the front fins. One of the reasons the thruster is the standard used in competition is the ability to break free that rear fin and allow tight snaps. Quads tend to produce a more rounded turn, canards either side of the rear fin would (I guess) tend to produce a rounded turn instead of tight snap.
 
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One-Off

Tom Curren status
Jul 28, 2005
11,201
6,054
113
33.8N - 118.4W
That's for the front fins. One of the reasons the thruster is the standard used in competition is the ability to break free that rear fin and allow tight snaps. Quads tend to produce a more rounded turn, canards either side of the rear fin would (I guess) tend to produce a rounded turn instead of tight snap.
I guess I have twinzer brain right now because when you said rear fin, I was thinking the mains and the canard are the forward fins.

I do like carves more than snaps. I always use the comparison between slalom skiing and giant slalom (or super G) turns. The bigger turns are more satisfying for me.

This has nothing to do with surfboard dynamics or surfing technique but it's just fun to watch-
 

oneula

Miki Dora status
Jun 3, 2004
4,252
2,398
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Although I was schooled as a physical oceanographer with a minor in cultural anthropology, I've been a treasury services banker for the past 44 years. So I don't profess to know anything about the physics of surfboards although when I got out of high school in the early 70's I toyed around the idea of making surfboards (I wanted to tape pin lines and sand) on the northshore with my KS classmates Brian Higa and Jules Kaluna or with my cousin Brian Hamilton. George Ku followed that path along with being a fireman, which was pretty common for us KS grads.

But the way Greg explained it to me was to think I was a drop of water as I looked at all the contours of his boards especially the bottom. And that the ultimate goal of his boards from rail to profile to rocker to outline to bottom contour was all built to make water leave the surface of of the board faster than it's entry speed. To "speed it along with the least resistance" as he would say. In that aspect his designs made allot of sense to me. And also that his fins were the engine of the boards which is why the need for the ultra stiff G10, because they could be foiled correctly and tabs setup off center but still have all the drive and push you needed against the water flow. That's why they felt like they were providing "lift" when in fact they were providing higher than average drive. In the end none of the explanations mattered as along as it worked and it did especially for weaker waves.
Now in the country when there is so much power in the wave, it's more about control management than generating speed. But in most places you need speed to be in control. Concaves, channels and vee are all about control than speed. But in the end its what ever works. Kind of like the pitchfork and assyms everyone laughed at until ryan made them popular off of Jeff's spiderman board I left at george's shop.

Good luck with the walnut
The two I did in Koa veneer do not do well in the hawaiian sun. I did a copy of a flyer and a stubbvector
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