T-Belly Gen 4x

What works and what doesn't. Share design ideas, references and contacts for paipo board builders.
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Re: T-Belly Gen 4x

Unread post by SJB » Sat May 28, 2016 10:56 am

Stealth bomber. A beauty. Price? Also interested in your analysis carbon fiber vs epoxy.

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Re: T-Belly Gen 4x

Unread post by nomastomas » Sat May 28, 2016 11:36 am

Carbon fiber cloth is about 5X the cost of E-cloth, but with that said, it only adds about $25 to the cost of a TBG4 (depending upon length, of course). Like many things, labor is the tall pole in the tent for glassing cost. CF is lighter and definitely more durable than regular e-cloth. Those Aramid fibers are tough. Laps have to be trimmed as soon as the epoxy starts to gel, or a razor won't cut it. Very stiff, although all the TBG4 are stiff (meaning no discernable flex) which I believe is one of the reasons they are so fast. My next G4 will be CF...maybe just on the rails...
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Re: T-Belly Gen 4x

Unread post by SJB » Sat May 28, 2016 12:47 pm

Hmmm.....so am to understand that CF makes for a more "ding proof" board? Are there any downsides to CF?
I guess what I am trying to get to....at only a $25 up charge.....is there any downside to going CF?

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Re: T-Belly Gen 4x

Unread post by nomastomas » Mon May 30, 2016 10:51 pm

Well, I've only surfed my Manta on head-high or bigger days, when crowds aren't an issue. So, I don't know how it (carbon fiber) will hold up to the typical rail-banging that occurs at a crowded break (haven't lost I on the rocks yet either!).
as for downsides, it is black, which may not be your favorite color.Some guys prefer a different color than black, which would call for painting over the hot-coat. My glasser does that all the time with SUPs, but it adds cost ($25 a side) on a TBG4. And of course, there are those who are convinced that flex is essential for "good" performance in a prone-board, so CF would be of no interest to them. Likewise if a board with some heft to it is preferred, the CF wouldn't fit in that category. Bu, I think those are pretty much the downsides.
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Re: T-Belly Gen 4x

Unread post by krusher74 » Tue May 31, 2016 5:34 pm

This isnt directed at your use of CF

But I find many people these days seem to think CF is the magic fix all material, when for many applications its awful.

Many of the bit/strips of CF used on many stand up boards these days the usage is all gimmick.

I think years back they made hollow CF surfboards which never took hold.

I'm trying epoxy over PU on my latest board to see how that feels/holds up. :?

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Re: T-Belly Gen 4x

Unread post by nomastomas » Tue May 31, 2016 9:43 pm

All of the SUPs my glasser builds are either CF deck and rails, or all CF. This is the standard for hand-laminated SUPs in California. They are frequently painted so that the CF is only visible on the rails. One exception are the down-wind racing SUPs being glassed for Jeff Clark, noted Maverick's pioneer. Jeff's SUP blanks are stringerless with CF on the rails for (1) protection against paddle strikes and (2) to add some strength to the 1.5PCF EPS. The flexiness of a 14' x 30" x 4.74" 1.5PCF EPS blank that is seen when on the glassing racks goes away almost completely as soon as the resin kicks. But your point is well taken. I once heard a well-known shaper remark, when asked about the function of the small carbon fiber rail patches on his shortboards reply, "I'm not sure, but I can't sell them without it."
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Re: T-Belly Gen 4x

Unread post by Daryl D » Thu Jun 02, 2016 10:14 am

I've worked with carbon fiber products for years in racing. It's tough, it's stiff, it's light, and it's pretty affordable. For years, I "didn't like" EPS epoxy stand up boards, too corky. My last stand up was a PU epoxy and I loved it. I still have an EPS epoxy long board for those small days! Legs were giving out and moved to wooden paipos. I really wanted a board that surfed rather than slide so I ended up with a T-Belly 2, EPS epoxy. too corky, but it would turn on a dime. The more I've surfed it over the last couple of years, the better I like it. Point being light and floaty isn't really bad and can be real good as you learn to deal with it. Also, I kind of like stiff. My next board is going to be CF and Thomas will shape it. Still deciding fins or not. What I expect from my CF experience is a tough board, not unrealistically so, but still more ding resistant, light, stiff and really cool looking, all for $25! Best yet, I still have the wood boards and surf them regularly as well. It's truly about the surf.

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Re: T-Belly Gen 4x

Unread post by krusher74 » Sun Jun 05, 2016 2:55 am

Daryl D wrote:I've worked with carbon fiber products for years in racing. It's tough, it's stiff, it's light, and it's pretty affordable. For years, I "didn't like" EPS epoxy stand up boards, too corky. My last stand up was a PU epoxy and I loved it. I still have an EPS epoxy long board for those small days! Legs were giving out and moved to wooden paipos. I really wanted a board that surfed rather than slide so I ended up with a T-Belly 2, EPS epoxy. too corky, but it would turn on a dime. The more I've surfed it over the last couple of years, the better I like it. Point being light and floaty isn't really bad and can be real good as you learn to deal with it. Also, I kind of like stiff. My next board is going to be CF and Thomas will shape it. Still deciding fins or not. What I expect from my CF experience is a tough board, not unrealistically so, but still more ding resistant, light, stiff and really cool looking, all for $25! Best yet, I still have the wood boards and surf them regularly as well. It's truly about the surf.
I have tried a couple of EPS epoxy boards and did not like them, but i think its down to there spring, they cant be "corky" as a 25L pu and 25L eps will float the same. I think the stringer/brittle poly glass stops the spring.

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Re: T-Belly Gen 4x

Unread post by nomastomas » Mon Jun 06, 2016 7:22 pm

krusher74 wrote:
Daryl D wrote:they cant be "corky" as a 25L pu and 25L eps will float the same.
Only if the PU foam and the EPS foam are the same density. Standard "Blue" density PU foam (US Blanks) is about 2.5-2.6PCF (pounds per cubic foot), with "Red" desnity 5%-7% lighter. Most surfboards using Marko Foam EPS blanks are 1.5PCF to 1.9PCF (aka "2lb"). making them liter-for-liter more buoyant. Similarly a liter of lead is less buoyant than a liter of cork. Bottomline, less dense more buoyant at any given volume.
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Re: T-Belly Gen 4x

Unread post by Cuttlefish » Wed Jun 22, 2016 5:07 pm

I am a fan of cf having owned a few cf boards from DVS and would like to know what dims you'd shape a board in cf with me being 6'1" and 85kgs? I was 92-95kgs but lost weight and also enthusiasm for surfing in general so need a board to explore some less ridden places.
I sold my trusty paipo as it had far too much foam for me and would like another board.
Could you pm with price and a shipping price to Sunshine coast (or Gold coast) thanks?
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Re: T-Belly Gen 4x

Unread post by nomastomas » Fri Oct 14, 2016 2:13 am

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)
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Re: T-Belly Gen 4x

Unread post by bgreen » Fri Oct 14, 2016 6:37 am

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

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Re: T-Belly Gen 4x

Unread post by nomastomas » Fri Oct 14, 2016 11:13 am

Bob...you're just gonna have to ride a G4 sometime :D
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Re: T-Belly Gen 4x

Unread post by bgreen » Fri Oct 14, 2016 4:30 pm

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

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Re: T-Belly Gen 4x

Unread post by krusher74 » Sun Oct 23, 2016 11:36 am

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. ;)

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Re: T-Belly Gen 4x

Unread post by nomastomas » Sun Oct 23, 2016 12:09 pm

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 :D
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Re: T-Belly Gen 4x

Unread post by krusher74 » Wed Oct 26, 2016 8:43 pm

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 :D

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. :?
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Re: T-Belly Gen 4x

Unread post by bgreen » Thu Oct 27, 2016 4:27 pm

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

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Re: T-Belly Gen 4x

Unread post by krusher74 » Fri Oct 28, 2016 8:51 am

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.

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Re: T-Belly Gen 4x

Unread post by rodndtube » Fri Oct 28, 2016 9:52 am

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/
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