TBG5

What works and what doesn't. Share design ideas, references and contacts for paipo board builders.
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nomastomas
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Re: TBG5

#11

Unread post by nomastomas »

Yeah, I boosted the nose to 3" and the tail to 7/8" at the stringer, but the V in the tail adding another 1/8" to the rail rocker. I also added more curve throughout the bottom, instead of the original, staged rocker. Intent here is to increase turning performance with a more continuous curve, since the board is already plenty fast. I think it will pay off more in larger surf. Although, I'd settle for some chest-high mush right about now.
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nomastomas
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Re: TBG5

#12

Unread post by nomastomas »

So...while I'm waiting for some decent waves to test this thing on, I thought I'd mention something I recently learned about carbon fiber. CF is about 5 times stiffer than S-cloth and 30% lighter. S-cloth actually has a slightly (6%) higher tensile strength-to-weight ratio and a slightly higher compression-strength-to-weight ratio. So, if you're looking for superior stiffness and lightest weight, carbon fiber is the way to go. But, if your looking for general toughness, S-cloth is the choice. S-cloth also cost about 60% less per yd. But, the "curb appeal" of carbon fiber is undeniable.
Here are some definitions:
Tensile Strength - Ability to resist a force before breaking
Elongation - Ability to stretch before breaking
Stiffness - Ability to resist deflection or deformation before breaking.
Density - weight/volume
"Toughness" - a combination of the first two stated above.

Here's a great video on a comparison between fiberglass, carbon fiber and kevlar https://www.youtube.com/watch?v=KHXVf0SaJpA
Last edited by nomastomas on Sat Sep 23, 2017 9:08 am, edited 1 time in total.
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Re: TBG5

#13

Unread post by belly rider »

Wow another beauty
FERRARI red that is. :lol: :lol: :lol:
See you soon
its all about the ride
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nomastomas
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Re: TBG5

#14

Unread post by nomastomas »

EXACTLY!
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Re: TBG5

#15

Unread post by krusher74 »

Very exciting design, Would love to try that finless. (maybe try again this winter :? )
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nomastomas
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Re: TBG5

#16

Unread post by nomastomas »

After sitting in its new bag for over a month, I finally got a chance to ride my ne G5. Here are my first impressions:

Conditions: Glassy, 4ft-5ft beach break, mid-tide rising. SW groundswell, with a touch of NW windswell. Just a little crowded, with a dozen shortboarders of various skill levels competing for waves across two A-frame peaks about 50yds apart.
Performance: Almost identical to the G4 in paddling and duck-diving. Take-offs are the late drop-in variety, again similar to the G4. I thinned the tail on the G5 by moving the thick point forward, which allows the tail to sink more at the tail, providing a more forgiving take-off. (The G5 remains more parallel to the surface regardless of how steep the face on take-off.) Again, like the G4, the G5 immediately engages the wave face and holds. But unlike the G4 where the rider can feel this engagement primarily in the rear ¼ of the tail where the fins are, on the G5, the rider can feel the entire “wetted” rail engaged in the wave face. The G5 rail feels much more engaged to the point that I believe I can reduce fin area, perhaps significantly. (less fin area=less drag=more speed) While as tested (with my favorite quad fin set FCS H2) there was no significant increase in speed noted, but no loss of speed either, despite the fact that the G5 has more rocker on both ends. I did notice that turns were easier on the G5, which I attribute to the continuous rocker of the G5 compared to the staged-rocker of the G4. The ultimate test of the rail performance would be to ride the shape finless.

Summary: The G5 equals or exceed the performance of the G4 in every category. I need to do continued research to optimize ideal fin area for a given wave size.
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Re: TBG5

#17

Unread post by bgreen »

Hello Nomas,

I was interested in your comment: "I thinned the tail on the G5 by moving the thick point forward".

Do you have a comparative photo of the respective G4 and G5 foils? How far forward is the new version?

Bob
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nomastomas
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Re: TBG5

#18

Unread post by nomastomas »

Comparing foils is difficult because the thickness of the rail masks the centerline thickness. And rail thickness is oftentimes what I use to add or subtract overall volume, so there is no consistent rail thickness shape to shape. I had a 49" G4, but it was 1/2" wider at 22" and 1/4" less thick at 1.75". On this G4, max thickness starts at 15.82" up from the tail and ends at 27.5", while max thickness on the G5 starts at 17.67" up from the tail and ends at 25.81" up. So, about a 3" shift forward.
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Re: TBG5

#19

Unread post by bgreen »

Nomas,

Thanks. It's interesting to see the shift forward from the original Goddard models which had the thickness way back - now more like a modern standard board foil.
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Re: TBG5

#20

Unread post by nomastomas »

tb1.jpg
tb1.jpg (187.61 KiB) Viewed 374610 times
This was my first T-Belly based entirely upon Goddard's work. It was 51" long and almost 3" thick. I found it hard to catch waves and prone to pearling on steep take-offs. I also found that it was not very good at holding into the wave face. It essentially felt too big for me in every dimension. A heavier rider might have had a much different opinion.

Over the next 7 years I made progressive tweaks in the shape, primarily thinning and shortening, but also playing with bottom contours. In each case, these changes were in service of my own biases, creating what I, personally, like to ride. Much of my foil changes have come from observing the shortboarders, with whom I frequently share a peak. Until the moment they stand up, they are essentially prone surfing. So, yes, my foil is now very similar to the common shortboard, albeit in a much shorter length.
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Re: TBG5

#21

Unread post by flojo »

that is a beautiful board-
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bgreen
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Re: TBG5

#22

Unread post by bgreen »

Nomas,

I posted my experiments with Larry's design. The first board was more like his standard board. My next board was a thinner version. No problems with nose diving and it is the fastest board I've ever ridden. It's suited to tube riding but a great board nonetheless.

The guy who shapes my boards is moving more to a standard surfboard type foil. I have a recent board I really like, that I want to go a bit thicker on, but not too much.

I look forward to seeing your further refinements, especially finless.
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Re: TBG5

#23

Unread post by nomastomas »

Every time I consider removing the fins on the G5, this happens: I take off late and deep, actually waay to late and waaay too steep. Getting pitched is inevitable, but...I grab the beach-side rail and with arms extended, falling into the pit, I use the G5 as a hand-plane, and leveraging the wave side rail and fins, I hook into the face and I'm off to the races.
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nomastomas
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Re: TBG5

#24

Unread post by nomastomas »

Well, this Winter was very hit-and-miss (mostly miss) surf wise at my local breaks. Catastrophic fires and floods, didn't help, either. With only a couple days of solid OH waves, I never got a chance to to tune in the fin setup on the G5. Once again I was plagued with the skipping stone phenomenon. It may be that the wide-point-behind-center design of the G5, while generating tremendous speed, generates just too much lift in larger waves. I think that, much like big wave surfboards, there is a need to reduce lift by narrowing the plan shape and reducing the volume in the rear half of the board. This would allow the tail to sink a little more, creating just enough drag to keep the board in contact with the water. I wonder if anyone else has encountered the skipping-stone and how you deal with it?
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Re: TBG5

#25

Unread post by rodndtube »

Over the years I thought about a similar challenge in dealing with skipping stone on larger, fast waves, especially susceptible when there is just a small amount of cross shop on the surface. It was never addressed front on, no pun intended, but what I had wanted to experiment with was adding a fair amount of "V" in the nose. In the end, my decision was to deal with one of my main concerns, my ribs, by buying a pair of lacrosse rib protectors, rather than a highly specialized board for one spot.
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nomastomas
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Re: TBG5

#26

Unread post by nomastomas »

For me, its the reduction in control that accompanies the skipping that is bothersome. In small waves (under 6ft face), lift helps to keep the board loose, by keeping it close to the air-water interface. Just skimming on, but still in contact with the surface is ideal. Less shape drag for max speed, but still enough control surfaces (bottom, rails, fins, etc) in contact with the water to maintain smooth directional control. Applying body weight to surfaces or changing attack angle in the case of fins, produces enough drag to alter course. So, my thinking is to reduce lift by eliminating bottom concave, reducing the overall planing area and reducing buoyancy by reducing the volume. Essentially, becoming more "displacement" hull than "planing" hull, and using different fin shape/sizes to fine-tune the ride. The "Manta" was a tri-hull, displacement design, but it shared the same wide-point back outline and foil, and suffered the same excessive lift problem in larger waves.

That being said, there is a certain thrill that comes from traveling at the speed where you occasionally feel almost the total absence of drag.
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Re: TBG5

#27

Unread post by bgreen »

The old Hawaiian footage shows the surfers skipping along.

Sometimes it is fun, but it can get dangerous. Rod mentioned his ribs, My chin hit the deck one day and my teeth went through my lip.

There are probably ways to reduce it, but if you are going at speed and there is some chop, I think it is hard to avoid. Lower volume, less surface area might be one way to go. But then you won't have a TBG5.
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nomastomas
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Re: TBG5

#28

Unread post by nomastomas »

TBXL!!!! Yes, and those "old Hawaiians" are probably riding the old style, wide-point behind center "guitar pick" shapes. Given that Winter has pretty much passed, I'll probably have another 9 months or so to come up with a testable design and a new name...

BTW, if you hold your board by the rails with hands apart, chances are that your elbows and forearms are off the deck, or at least not under your chest. Holding the board with both hands together on the nose with elbows/forearms on the deck (a la bodyboard) helps to protect upper body from the deck.
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Re: TBG5

#29

Unread post by Nels »

Speaking of "old Hawaiians" and old school paipoboarding and bellyboarding, a lot of guys rode with their heads forward of the nose of their boards and the arm nearest the wave outstretched. Not so good for pearling probably but would give some protection to the old chinbone. Also moved the weight forward for ultimately less friction. I have a couple of magazines with photos...a Surfer from maybe 1971 and the 1972 World Contest program I think had one (relying on memory on that one). I also saw that in Honolulu back in the early 70's.

With my two (finless) wood paipos I would get the bounce but countered that with hanging my lower half off the near-wave tail corner. Felt okay, but intellectually seems like trying to go two cosmic directions at once. I'm trying to cut down on that action...

Nels
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Re: TBG5

#30

Unread post by bgreen »

Nels,

I think the forward riding position was suited to short boards. In an interview (Barry Hutchins I think) it's referred to as a cantilever position.

On a longer board, weighting the tail could lead to nose slapping. An optimal length board, would allow what you suggested, dragging the body but also having some weight forward. The other option is reducing the board area in the wave through more on rail surfing.

Here's hoping there isn't a need to engage in too much chop surfing. It's one of those things worth experimenting with. Easier said than done, because when you're skipping, you are typically hanging for the ride.

Bob
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