T-Belly Generation 2

What works and what doesn't. Share design ideas, references and contacts for paipo board builders.
Poobah
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Re: T-Belly Generation 2

#41

Unread post by Poobah »

Soulglider, what blanks have you been using? What does Austin use on his bellyboards?

I was looking at the US Blanks catalog. This 8'8" EPS looks like it could make two boards with room to spare.

http://www.usblanks.com/catalog/?tid=8& ... ightbox/0/
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Re: T-Belly Generation 2

#42

Unread post by rodndtube »

Austin uses Poly, definitely not EPS. Not because EPS is bad, rather he specializes in retro-feel style surfboards with heavier glass and resin and he also is known for his artistic color resin work and patterns... EPS/epoxy are not as "art friendly." For example, the Checkered RPMs color patterns are all raised colored resin, not air brush. The first ever Austin paipo, the Orange Matter, is a swirl resin design. Austin also does some very nice woodwork including tail blocks, stringers, etc.
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Re: T-Belly Generation 2

#43

Unread post by jbw4600 »

I made my board out of a sheet 3 inch x 4 feet x 8 feet EPS construction foam. I got it at White Cap construction supply. (many in California). for $48.00. I can make 3 boards out of it. So there is no rocker and no stringer. I had to shape the rocker and everything else. I am getting ready to build another one.
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Re: T-Belly Generation 2

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Unread post by soulglider »

rod: sorry about that Part 2 was about rails and things, Part one ( http://surfmatters.blogspot.com/2014/05 ... 4-law.html ) included width among other things. I like a lot of other folks (we're all lemmings of some sort i guess) just followed along thinking thinner, more hold, not necessarily true.

poohbah: i use the poly U.S. Blanks 5' 9A blue blank for my boards. Say hi to micro red!
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Re: T-Belly Generation 2

#45

Unread post by krusher74 »

jbw4600 wrote:My board is made from 2lb EPS. I think that EPS is 15-20% more bouyant. I guess the increased bouancy with less volume and lightness makes it feel lively.

Ok that's a good starting point, in poor waves literage/flotation does not bother me so much, but in good waves I despise a board with to much flotation :(
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Re: T-Belly Generation 2

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Unread post by krusher74 »

soulglider wrote:check this out if you dare. design theory made fact through one guy as close to the little yellow haired surf idol, GG. its why my boards are under 21" wide, more interesting things too.http://surfmatters.blogspot.com/2014/05 ... aw_26.html
So are you saying your boards are under 21" wide because of the optimum 2:1 ratio mentioned in this article? Arnt they taking about a rectangular board for straight line speed.

Would that thinking not need a 10f longboard to be 5ft wide? :?
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Re: T-Belly Generation 2

#47

Unread post by rodndtube »

Yes... for the optimum!!! Lindsay Lord also cited a range within the optimum planning. Obviously, we wasn't going to build high speed smuggling interceptor boats that were 40 ft by 20 ft ;)

Many people think that the original boogie board was somewhat accidental but Tom Morey actually brought some thinking man knowledge to the design. The 42x21 boogies board or 40x20 is the ideal. 50x20 in barely within the range of optimum aspect ratio. Chamberlain's ultra large paipos are probably approaching the optimum range simply because they are so wide (~29 inches).
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Re: T-Belly Generation 2

#48

Unread post by soulglider »

"Misconceptions about round rails came about in the late 60’s, when stand up surfboards suddenly dropped in width from over 22” wide to under 19” wide…a huge difference. Experimental low rails accompanied that shift in thinking, and because the new narrow miniguns held in better, most people concluded that low rails were the reason why. In truth, it was the severe reduction in width that was providing the added hold that was so exciting to everyone at the time...but the myth that low rails were the deciding factor in this improvement persists to this day."

tomas was talking about getting his boards to ride higher and tighter in the wave and in the barrel-this is why i stick with under 21inches. all my wider boards slip to some degree but the ones over 21" slip side slide but, narrower with full but sharp hull rails hold like a mother in the toob with plenty of release for maneuvers.
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Re: T-Belly Generation 2

#49

Unread post by Nels »

Many people think that the original boogie board was somewhat accidental but Tom Morey actually brought some thinking man knowledge to the design. The 42x21 boogies board or 40x20 is the ideal. 50x20 in barely within the range of optimum aspect ratio. .
Tom Morey took a USC math degree in 1957, earned while being one of the top Malibu surfers of the era, into aerospace engineering with McDonnell-Douglas during the late 50's-early 60's. While he (probably) wouldn't have known Simmons, he certainly was in contact with many who did. Morey and early partner Karl Pope have to be among the most material and process- focused builders of surfcraft in surf history.

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Re: T-Belly Generation 2

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Unread post by nomastomas »

I fully agree with Rod, that its important to look at the interaction of all design features on any given performance outcome, be it turning, paddling, wave-face-hold, etc and not just one design feature. Wide-tailed single-fin boards don't hold-in as well as narrow-tailed single-fin boards. But, wide-tailed boards with rail fins, e.g. quads, twins, do.

With that in mind, I think I've discovered the cause of my wave-face hold problem, and I don't believe it was the width, per se. Rather, it was the location of the fins relative to the wide-point. All LB and SB outlines (plan shapes) have a wide-point (WP), and some have a spot at the tail where the outline curve rapidly accelerates, i.e. hip or bump/wing. The rail-length of the G2 is so short, that the WP actually serves as a "hip" as well. I had this in mind when I picked the fin location. Then I got caught up in mimicking the Bonzer fin stuff, where the smaller/shorter fin is placed in the front and the larger/taller in the rear. This is the opposite of how most shapers set their quad fins. On my second session with the G2 I replaced the Bonzer side-runners with the front fins from a "split-keel" quad set I have.

I placed them in the rear position and had a go. Waves were chest-high and inconsistent, so there was a bit of a wait between good waves. Board speed was pretty much unchanged, as was turning response. When I attempted to trim to a higher line across the inside section, I got about half-way up the face (improvement over the Bonzer fins) but then suddenly I felt the fin pull out, and the tail start to slide down the face about a foot, at which point the fin re-engaged. This happened a couple of times, when in that same steep inside section. This was about 5 days ago, and we're into the summer doldrums around here so there has been no ride-able surf since then. But, I've been mulling over fins, fin placement and the like when it suddenly occurred to me what was going on. Looking at he G2's outline, it seems embarrassingly obvious that the larger/taller fin needs to be in the front fin position for optimum hold. The front fin position is closer to the WP/hip and closer to the rail than the rear fin. On the G2, the rear fin position puts the fin too far away from the rail due to the curve in the outline and the location of the the fin box further from the rail. I haven't had the opportunity to confirm this hypothesis, but I'm convinced it will be proven true. Another approach would be to move the WP back even further and/or flatten the outline curve behind the WP by increasing the width of the tailblock. This would also increase the drive out of a turn, but would widen the turning radius. May be a better shape for larger waves, where you want/need maximum projection out of the bottom turn. Hmmm....
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Re: T-Belly Generation 2

#51

Unread post by krusher74 »

In the picture of your board above it is obviously a very blunt nose.

The bodyboard I used as a template for my paipo was a 41.75" but for cosmetic reasons more than anything (did not want my paipo to look like a fiberglass bodyboard) carried the rail curve forward to a point. making it measure 44", so just point out the board length in simple measurements can be misleading.

I would say if were looking for a 2:1 ratio then most paipos are pretty close if you start looking at 6f by 19" short stand up boards your getting in the 4:1 range and they seem to work pretty well for the likes of kelly slater. (although he is going shorter these days!)

I pretty glad I don't have to worry about fins and there placement it sounds very hard to get right. :?

I have tried 3 finned paipos and struggled with all of them, I find they either track in a straight line and are very hard to turn, or to turn them i have to move to get my weight and pivot point over the fin/s
I found in a forward position for speed with the fins behind my balance point the board will track, so to then turn i have to move back then the board will turn, but I then have also slowed the board by moving back, I found this to be worst on the longest board I tired. It was like a gymnastic work out trying to move around fast enough to make critical turns, once back on my finless these movements are smaller and effortless
Maybe this is why you finned paipo rider seems to prefer the wide point further back nearer the fins, riding with most of your weight on the rear of the board?

Is the difficulty in riding high and tight, or trimming back up the wave because the fins are driving you down the wave face? :?

As an experiment have you though of trying the board with just 2 fins in either the front or back position, or even finless?

My friends paipoglide that tracked horribly for me with a small twin fin set up, went I tried it finless was much, much better and even with a rail not designed for finless riding I can break the rail free for a 360 and easily get it to grab once round for forward traction.
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Re: T-Belly Generation 2

#52

Unread post by bgreen »

Thomas,

It will be interesting to hear how the changed fin configuration rides. Would you try this with or without the centrefin?

Soulglider,

Interesting posts from Paul Gross. I tried to find # 1 of his tinkering series.

Bob
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Re: T-Belly Generation 2

#53

Unread post by nomastomas »

I only used the two larger front fins, but I placed them in the rear boxes. So, it was a twin-fin set-up.

Tracking on finned surfcraft usually comes from lack of fin toe-in. On the G2, I set the toe-in at 1/8" on both front and rear, again following the Bonzer set-up (but 1/8" instead of 1/4"). I set my typical quad boards at 1/4" toe-in front and 1/8" toe-in rear. Pretty much industry standard. More toe means less "go", which is why traditional fish (surfboards and/or kneeboards) with double-keel fins set straight (no toe-in) are extremely fast but a little stiff.

I don't think center fins are necessary on a multi-finned board, unless the rider doesn't like the feel of slight drifting when transitioning from one rail to the other. There is a point during the rail-to-rail transition when neither rail is fully engaged, and there is a slight, momentary drift to the outside of the turn until the inside rail and fin fully engage. I believe this is more pronounced on a stand-up board Some people don't like twinnies for this reason, or they add a small center fin to smooth out the transition.

Perspective is an interesting phenomena. I would say that the side-slip, tail slip I experienced reminds me of what I dislike about finless boogie boards. Not a big fan of 360s either, which to me seems like what a finless rider does when the inevitable happens and they start to tail-slip down the wave face. Making lemonade from lemons perhaps?
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Re: T-Belly Generation 2

#54

Unread post by bgreen »

Hello Thomas,

I thought you were going to move the big keels to the forward position. On fat waves waves/in the white water I found 4 fins can slip but were otherwise fine. I was looking into a 4 -5" centre fin. Unlike your fins, the bonzer keel fins are quite angled. I should try some straight fins.

Bob
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Re: T-Belly Generation 2

#55

Unread post by nomastomas »

yes, I plan to move them forward, but haven't had a chance to try that out yet.

My FCS Fusion boxes have 5-deg of cant and my Bonzer side runners have 19-deg of cant built into the fin. That yields a total of 24-deg of cant, which is typical for Bonzer surfboards. Most fin set-ups benefit from 3-deg to 5-deg of cant. Actual fin Cant varies according to cant manufactured into fin, fin boxes and bottom contour (amount of V, concave, etc) in bottom.

My plans for fin testing (depending upon wave conditions, of course) are:
1. Split-keel front fins in the front box as twin-fin - I just like the size and template of these fins.
2. Bonzer quad side-runners in reverse position, with larger fins in front and smaller in back - The low-profile Bonzers SRs are speedy as hell!
3. T. Patterson quad-set, 4.35"Hx4.3"B front, 3.95"Hx3.85""B rears - Typical shortboard quad set-up, in terms of size and template.
4. TA Side-Bites quad-set, 3.7"Hx3.55"B Front, 3.25"Hx3.25"B Rear - This is smallest quad set that I know. They should be fast, but will they hold?
5. TA Side-Bites as Twin set in front boxes. - May be all the fin required in the small stuff.

I've never experienced a slipping problem with quads with the right fins in the right position, the right fins for rider-size (bigger riders need bigger fins) and/or the right fins for wave conditions (bigger/steeper waves need more rake and more height). On the other hand, I normally go from a quad to a tri-fin or twin-fin set-up in smaller waves to reduce drag.
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Re: T-Belly Generation 2

#56

Unread post by soulglider »

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Re: T-Belly Generation 2

#57

Unread post by GeoffreyLevens »

krusher74 wrote:The bodyboard I used as a template for my paipo was a 41.75" but for cosmetic reasons more than anything (did not want my paipo to look like a fiberglass bodyboard) carried the rail curve forward to a point. making it measure 44", so just point out the board length in simple measurements can be misleading.

I would say if were looking for a 2:1 ratio then most paipos are pretty close if you start looking at 6f by 19" short stand up boards your getting in the 4:1 range and they seem to work pretty well for the likes of kelly slater.
I think this points to something quite important in terms of that 2:1 ratio and what it means in practice. We really need to be comparing actual functional dimensions, that parts that are working in/with the water. The "given" dimensions of the chopped off looking wake style surfboards that are now the fad, similar to the shape bodyboards have always had, is really the essence of that i.e. only the useful/functional part is there and the visual appeal parts removed. I do like prefer the look of the extended but round nose vs the chopped off square. But then, for packing and getting it in a small transport case, cutting down is good.
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Re: T-Belly Generation 2

#58

Unread post by nomastomas »

Form should always follow function...
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krusher74
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Re: T-Belly Generation 2

#59

Unread post by krusher74 »

nomastomas wrote:

Perspective is an interesting phenomena. I would say that the side-slip, tail slip I experienced reminds me of what I dislike about finless boogie boards. Not a big fan of 360s either, which to me seems like what a finless rider does when the inevitable happens and they start to tail-slip down the wave face. Making lemonade from lemons perhaps?
If your slipping the rail on a bodyboard your not driving properly through your inside rail hip bone and elbow and not pulling up with your outside on the rail hand towards the tail of the board. Tail slipping inn not inevitable.

A 360 sliding down the face is not the way its done, you either for a forward spin turn up the face hard, move you bodyweight forward to the center of the board, lift and fling your legs to break rail traction and slide he 360 on the flat of the board, when you get round you lean back on the rail to make it bite again

To do a reverse 360, for off the lip 360 blow tail like a stand-up surfer would and spin as above, or cut back and perform the spin back to he pocket.

have a look at these videos

forward 360 https://www.youtube.com/watch?v=chfyJthGGL0

reverse 360 https://www.youtube.com/watch?v=-X0aCjoZm3o
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Re: T-Belly Generation 2

#60

Unread post by nomastomas »

All very instructive, but still not very interesting. To me, regardless of the specific technique, such "tricks" are simply a creative use of a finless board's tendency to loose traction on the wave face. Your argument that a finless board hold as well as a finned board is contrary to what I have experienced and/or observed. We'll just have to agree to disagree.
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