MyPaipoBoards Forums

Its been 18 mo. since I built the first G4 and I'm still riding it. It has a couple of battle scars (rail dings from being dropped-in on!) but otherwise has held up really well. I've built 15-16 of these, and except for variations in length and volume to accommodate rider height and weight, the design has remained un-changed. The shape has received excellent reviews from its owners, particularly the perceived speed and responsiveness of the shape. I've received so many inquires about the shape that I finally sat down and constructed a drawing explaining some of the design features. I thought that a few of the readers might be interested seeing it, although there a few who may consider my ideas rubbish. To the former I say "If you see something that makes sense to you, don't hesitate to use it on your next build." and to the latter I say "Don't waste your time looking at it." I've already gone into great detail on this forum explaining the design of the G4, and feel no need to regurgitate it here. But I think many, if not most, of the builders on this forum are "visual thinkers", and the diagram below is a good summary of the essential features of this shape. The board in the drawing was built for rider 6-2/230lb, so it is larger than the G4 built for the average 5-10/180lb rider. (Interesting that most of my customers for the G4, both men and women are over 40yr of age)

Nomas,

Thanks for taking the time to share your ideas.

My recent surftrip highlighted for me, that no one design is suitable for all conditions; and what works for one person may be a dog for another.

Bob

Bob...you're just gonna have to ride a G4 sometime

Nomas,

I'll post some photos on my new board thread. There is a new board in the thinking phase that may move a bit closer to the ideal board (for me at least). A quiver of boards isn't a bad thing.

Bob

nomastomas wrote:Its been 18 mo. since I built the first G4 and I'm still riding it. It has a couple of battle scars (rail dings from being dropped-in on!) but otherwise has held up really well. I've built 15-16 of these, and except for variations in length and volume to accommodate rider height and weight, the design has remained un-changed. The shape has received excellent reviews from its owners, particularly the perceived speed and responsiveness of the shape. I've received so many inquires about the shape that I finally sat down and constructed a drawing explaining some of the design features. I thought that a few of the readers might be interested seeing it, although there a few who may consider my ideas rubbish. To the former I say "If you see something that makes sense to you, don't hesitate to use it on your next build." and to the latter I say "Don't waste your time looking at it." I've already gone into great detail on this forum explaining the design of the G4, and feel no need to regurgitate it here. But I think many, if not most, of the builders on this forum are "visual thinkers", and the diagram below is a good summary of the essential features of this shape. The board in the drawing was built for rider 6-2/230lb, so it is larger than the G4 built for the average 5-10/180lb rider. (Interesting that most of my customers for the G4, both men and women are over 40yr of age)

Thanks for sharing the pdf info, i bet it would go well finless if the rail bottom edge stayed soft.

Yep, funny that many people falsely believe that hard edge holds better than soft edge, when in fact it doesn't. Hard edge encourages water to break off/release. Water wraps around soft, round edge creating better hold (but more drag). The "tucked" edge, an egg-y rail shape with a defined edge where rail meets a flat bottom, offers the best of both worlds. Water wraps around the rail until it encounters the edge, where it breaks off. The much marketed "Vacuum rail" of the Morey Boogie is an artifact of the manufacturing process. A CNC hot-wire cannot cut curves in the "Z" axis, only straights. The resulting dual-faceted rail is a gross approximation of a curve, and performs much better than a square block. So why the down rail on the rear of most modern surfcraft? With the fins providing hold at the rear, the rear rail can be designed to release water for max speed.
...and yes the G4 does work well without fins, just not as well

nomastomas wrote:Yep, funny that many people falsely believe that hard edge holds better than soft edge, when in fact it doesn't. Hard edge encourages water to break off/release. Water wraps around soft, round edge creating better hold (but more drag). The "tucked" edge, an egg-y rail shape with a defined edge where rail meets a flat bottom, offers the best of both worlds. Water wraps around the rail until it encounters the edge, where it breaks off. The much marketed "Vacuum rail" of the Morey Boogie is an artifact of the manufacturing process. A CNC hot-wire cannot cut curves in the "Z" axis, only straights. The resulting dual-faceted rail is a gross approximation of a curve, and performs much better than a square block. So why the down rail on the rear of most modern surfcraft? With the fins providing hold at the rear, the rear rail can be designed to release water for max speed.
...and yes the G4 does work well without fins, just not as well

I still dont understand the physics of whats happening with a flat chine, but after trying a normal surfboard rail on one of my paipos as an experiment (without hard edge) it does not have the positive locked in feeling and hold i get when i give that area a lower flat chine.

Keith,

Do you still have the board? Make a thin resin edge and add some sharpness and see what difference it makes.

With the blue board - the SDF no4 (US blanks green Pu 5.10RP) thread, you wrote "Well today I was looking at the board and it had a hard edge on the back 3rd of the rail and a faint hard edge as far as two 3rds up, so I got the sandpaper out and sanded all off.

Result hold and drive is back! totally changed the board >,

So how d the rails of the two boards compare?

Bob

bgreen wrote:Keith,

Do you still have the board? Make a thin resin edge and add some sharpness and see what difference it makes.

With the blue board - the SDF no4 (US blanks green Pu 5.10RP) thread, you wrote "Well today I was looking at the board and it had a hard edge on the back 3rd of the rail and a faint hard edge as far as two 3rds up, so I got the sandpaper out and sanded all off.

Result hold and drive is back! totally changed the board >,

So how d the rails of the two boards compare?

Bob

I was comparing a chine rail and a normal surfboard rail (no hard edges) and the chine has the more positive locked in feel, can turn hard both off the top and off the bottom with the chine rail. never tried the chine with a hard edge but i would just expect that to make it slip and slide more.

Not sure what is meant by a normal surfboard rail and where along the rail line from nose to tail.

A summary discussion of rails here:
https://essentialsurfing.com/rail/

Rod, I don't want to put words in someone else's mouth but I think he meant to compare all 3 of your diagrams as "normal rail" to this i.e. "chine rail"

My read was inconclusive as to the "standard" rail type being compared and whether or not that standard was throughout the entire length of the rail. The behaviors of the "standard" rail types vary widely.
P. S. The chine is also in the figure I posted but need to scroll down.

I don’t understand Slab sided boards, in nature and in engineering nothing that works in water finishes without a taper??The explanation I get is to slid a wing profile side ways ??

GeoffreyLevens wrote:Rod, I don't want to put words in someone else's mouth but I think he meant to compare all 3 of your diagrams as "normal rail" to this i.e. "chine rail"

Yes, that's basically what I meant. (i'm only talking about the back 3rd of the rail as this is what i'm bottom turning of and finding the loose vs locked in difference.

My "normal rail" is a tucked performance shortboard rail (although maybe of a higher volume for the boards size)

And my chine rail is an extreme bottom chine, just round over into deck of board.

Here is a pic , (my scale is off thought so the bottom rail is drawn to big try to imagine them at the same board thickness)

Bodyboards having hard edges everywhere should release water and have poor hold, but they dont so what's going on there? Maybe I should e-mail tom morey.

If I am reading you correctly the rail holding issue is with turning and not holding a line on a steep wave face. Maybe that has something to do with the geometry of the rail to the wave face if you are turning on the rail (on a finless board) which would become more exaggerated for a thick rail board with lots of float. If I am visualizing this correctly a hard rail turn with a hard surfboard rail on the steep wave face a person is virtually turning on the top side of the board and not the "hard" edge of the rail whereas the 50-50 rail would have an edge in the wave face.

rodndtube wrote:If I am reading you correctly the rail holding issue is with turning and not holding a line on a steep wave face. Maybe that has something to do with the geometry of the rail to the wave face if you are turning on the rail (on a finless board) which would become more exaggerated for a thick rail board with lots of float. If I am visualizing this correctly a hard rail turn with a hard surfboard rail on the steep wave face a person is virtually turning on the top side of the board and not the "hard" edge of the rail whereas the 50-50 rail would have an edge in the wave face.

just holding a line you can't feel much difference, but once bottom turning hard,(on take off or along the wave) you ask the rail for grip and that's when the difference is apparent. Mayye you are right and what happening is it's using the top edge of the rail.
So its not a chine rail, it a flat faced up rail.

Here's a photo of one of my New England customers getting the most out of his G4. This one is a twin-fin, but he just ordered a G4 3" shorter and with Quad-fins. This is a prime example of one the values of CNC shaping. I was able to shorten the length, while keeping the same outline in the rear-half of the board. The shortened length required a 1-1/2" wider nose than the 46 in order to maintain a similar outline curve. I added 1/8" thickness to maintain the same volume (19L), but retained all of the same bottom contours.

It will be interesting to hear what the guy thinks of the twin vs the quad.

The single, most frequent comment I get from new G4 riders is how fast the board is compared to whatever else they have ridden. I believe that this speed (in most cases) comes from being able to harness the power of the wave that exists in the upper third of the wave face',i.e. maintaining a high line. As I have often stated, I believe that maintaining a high line is directly related to the use of fins, with fin size as the defining variable. I always recommend a quad set-up because it allows a wide range of fin area that can be adjusted to match rider weight and specific wave size. But often times, my customers are convinced that they only need a twin-fin board. And, choosing standard LB side-bites doesn't help. This particular customer is a case in point. He started with 3.7x3.5 side-bites and found that he was side-slipping a bit in critical parts of the wave. I encourage him to increase the fin size to 4.5 deep which helped a lot. Then, after gaining some experience with the shape, he decided to move to a shorter length, and a quad set-up. I recommended 4" front fins and 3.7" rear fins for his weight (165lb in wetsuit) and for waves like the one pictured above. A rider whose weight is under 150lb can get away with a twin-fin G4, as long as they use fins that are 4' or bigger. I have a few female customers that fall into this category.

Nomatomas,

I'll try to start a new thread on what I reckon some of my boards do best I haven't had a problem keeping a high line with finless boards, I have had some issues with low volume boards having less stability when there is turbulence or push from white water.


Bob