TBG5 Step Up

[CHRISPI]

Nice board how did you get that gorges satin black finish ? Great logo .The only thing I don’t get is dragging all those non lifting foils through the water ?

[Cuttlefish]

Phfooaaar!
Darth paipo indeed!

[nomastomas]

Chrispi - the board was constructed with carbon fiber cloth which is black. After sanding the gloss coat to 320g, he finishes up with a fine grit scrub pad. End result in this case is a stealthy looking satin finish. On clear, non CF cloth, the board looks almost polished.

"The only thing I don’t get is dragging all those non lifting foils through the water?"
Why would I, a production shaper, attempt to add a "lifting foil" to a simple prone-board? Hydrofoil application in marine design has been around for years, but there has never been public demand for it. A quick trip to your local marina or surf break proves my point. IMHO, for all the great science involved, hydrofoils are simply "not ready for prime time." Better left to the laboratory and/or the hobbyist to work out the bugs. While I admire your engineering and craftsmanship, to me its just interesting science, but not relevant to my world.

[Poobah]

I've read that the rear fins can be more vertical in this kind of set up, and it looks that way in the photos. Do you have measured numbers on the difference in cant?

I imagine this fin arrangement has been done on kneeboards. Are there any previous examples of it on a paipo or sponge?

[nomastomas]

Bruce McKee has done a ton of research on quad fins, both fin placement and fin shapes. ( http://www.mckeesurf.com/) If you want to go quad, you owe it to yourself to study everything he has to say on the subject. IMHO, he's "the guy" when it comes to quads. In a nutshell, the first quads had the rear fins set the same distance of the rail as the front fins. This gave the board a decidedly "twinnie" feel. McKee systematically moved the rear fins closer and closer to the stringer and found that at a certain position, the board had the best characteristics of a twin and a thruster. When using the McKee formula, he specifies the distance between the rear fins based upon tail width at 12" up. He also specifies cant and toe-in. I'm really oversimplifying here, but I use his "formula" on all my quads and I've never been disappointed in the results.

Regarding the rear fins, he recommends that they be set at about 2deg cant. He has a close working relationship with FCS and his recommendations fit quite easily with FCS hardware. FCS boxes come with 0, 5 and 9-deg of cant. I use FCS center fin boxes for my rear fins, so they have zero cant. (Note: "a number of shapers will take their cant relative to an imaginary plane perpendicular to the stringer at the center of the side fins. If you make your cant relative to the bottom of the board, boards with vee will have a greater angle of cant relative to horizontal and a board with concave will have less."-Tom Daum - See more at: http://www.swaylocks.com/swaylopedia/te ... qWf34.dpuf) Since I usually also have some V back where the rear fins sit, in most cases I have 1-2Deg of cant in the rear fin. Which is the case with the Manta. For front fins, I use FCS 5deg boxes, and again with Vee, this comes out to about 7deg cant relative to an imaginary plane set perpendicular to the bottom. If I wanted more speed and less responsiveness I'd go with less cant, how much less would be determined by bottom contour where fin is to be placed. Yeah, not very "exact". There's a lot of just "eyeballing it" with a fin and fin box, keeping in mind what McKee recommends and that the glasser has to install the box relatively flat to the bottom contour. In the end Build it, take it out, make mental notes, modify next iteration, repeat.

And, yes, McKee has a formula worked out for kneeboards, but as far as I know, I'm the only one building quad prone-boards other than the occasional one-offs here and there. The Manta is my first p-board utilizing a heavily McKee influenced quad configuration. The previous G3s and G4s were setup with the more traditional close-to-the-rail rear fin placement using 5deg boxes and 0deg boxes. This was largely because of the double-concave bottom contour, and now that I think about it, may have more to do with that shapes "twitchiness". Choosing a V-panel tail for the Manta open the way to using the McKee formula.

[CHRISPI]

Thomas I am trying to be as respectfully as I can but this multi fin craze is out of control . They seem to be a blinge fashion accessory like jewellery or fancy shoes , the cost of mould made brand name fins is ridicules , and are sold more for their flashy inlays and colures than performance improvements . Basic fine design hasn’t changed in 20 years ?I have seen boards with up to 6 fins !, if it pays the bills you have to go with the flow. The FCS marketers are brilliant. RANT over

[soulglider]

"but as far as I know, I'm the only one building quad prone-boards other than the occasional one-offs here and there." how many paipos/prone boards have you made? I SAY, anyone making paipos can be considered "making occasional one-offs here and there." no one guy has down THEE formula or is THEE fin guru! Just "IMHO" is the correct opinion - Chrispi is right-hype hype hype! ALL Fin combos work! there is NOTHING DEFINITIVE IN SURFBOARD DESIGN! otherwise we would all be riding the same thing. the right combination all shaped elements + fin(s) makes for magic and one time magic at that! even with errrr expert shapers using shaping machines with the same "exact" blank etc, wont be able to duplicate. trippy deal.

STILL, its a bitchin' looking experiment, nice job.

[soulglider]

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[soulglider]

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[soulglider]

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[soulglider]

"but as far as I know, I'm the only one building quad prone-boards other than the occasional one-offs here and there."

how many paipos/prone boards have you made? I SAY, anyone making paipos can be considered "making occasional one-offs here and there." no one guy has down THEE formula or is THEE shaper or fin guru! your just "IMHO" is the correct opinion - Chrispi is right too-hype hype hype! ALL Fin combos work! there is NOTHING DEFINITIVE IN SURFBOARD DESIGN! the right combination all shaped elements + fin(s) makes for magic and one time magic at that! even with errrr expert shapers using shaping machines with the same "exact" blank etc, we wont be able to duplicate. trippy deal, but true.

STILL, its a bitchin' looking experiment, nice job.

[nomastomas]

Chrispi – The effectiveness of a quad-fin configuration is undeniable. If the quad were not effective, just mere “blinge fashion accessory like jewellery or fancy shoes” as it seems to you, then I doubt that it would be ridden at places like Mavericks or Jaws. In waves of consequence, there’s more on the line than looking hip with the latest fad or endorsement money, namely the survival of the rider. If quads didn’t work as well or better than any other fin configuration, you wouldn’t see them at these venues. And, yes, there is a lot of marketing hype surrounding all surf equipment, and manufactured fins have a high profit margin. The same can be said for just about any massed-produced product. That doesn’t detract from the effectiveness of the product. It either works or it doesn’t, regardless of “bling” factor. I like quads but most of my p-board customers prefer a twin fin configuration. With two additional fin boxes and two additional fins, quads are more expensive. And, while they offer a greater opportunity to fine tune the board-fin-wave matrix, they also require more tinkering. Some people like to tinker, others don’t. To say that multi-fin set-ups are all hype is simply unsupportable.

[nomastomas]

SG – I see you’re back, with both guns blazin’. Its kinda cute how you posted the same comment in triplicate to sort of emphasize your point…just not sure what your point is? Beating the old “everything works, they just work differently” drum has really become boring to me. Some designs actually work better than other designs. You could just skin and glass a blank, stick an fin on it and it would "work". But a blank shaped by Wayne Rich or Jim Phillips would "work" better by any definition. Besides, your mantra appears to be a bit out of place in this thread, since I’ve made no claim that the Manta or quad fins are better than (you-fill-in-the-blank). However, I can see you’re anxious to participate in this thread, and I was actually hoping that you would pick up on the tri-plane design of the Manta and relate your own experiences with its near-cousin the “hull” design, which you’re so fond of. Perhaps that approach wouldn’t be adversarial enough for your taste? That’s unfortunate…

Actually, I haven’t built any paipos, but would like to some day. But, I have built a few prone-boards, in fact 13 just this year, 10 of which were custom orders (three are demos). Over the last 7 years or so, I think I’ve built around 30, probably 2/3 twin-fin and 1/3 quad-fin, mostly custom orders but a few “demo” boards as well. My first T-Belly was a one-off, and the next 5 or 6 were also what I would call one-offs. That all changed for me about 3 years ago with the TBG2, and my annual p-board production has increased continuously since then. At this time I’m pretty sure that I’m the only shaper on the West Coast that not only routinely builds quad p-boards in numbers greater than 1 or 2 every year (and not just for personal consumption), but who actually rides them as well. And before you fire off 4 identical responses to the effect that no one is better than anyone else, note that I did not say I was the “best” quad-fin p-board shaper, just the only quad-fin p-board shaper. Please post the name of any shaper on the West Coast who does more than 10, no make it 5 p-boards a year. I'd really like to see what they are doing. This year I had requests from as far away as Italy, Florida and the Pacific Northwest, not to mention Nor-Cal and So-Cal. The reason, I’ve been told consistently, is because I’m the only shaper building p-boards on a production basis, and just as importantly, I don’t consider P-boards a novelty. I consider them a legitimate alternative surfcraft, and my production numbers and my commitment to furthering the design show just that.

Lastly, while I hate to disagree with your egalitarian point of view, there are in fact some who are more knowledgeable, more “expert” in some areas than others. Bruce McKee is just such an expert with regard to quad fins. And that is not just in "my humble opinion", but in the opinion of most shapers, pro or amateur.

[CHRISPI]

Thomas on a lighter note I posted that reply in a OMG what has he done responce.By not following the post thoroughly I thought that it was going to be finless board .I had envisioned this gorgeous sleek finless stepped hulled beauty. With thus sponsens or horns ? that give it that aggressive look. And then to find her dressed in that tawdry FCS jewellery was a big let down ?

[nomastomas]

"...In the eye of the beholder" LOL.

[SJB]

Well it all makes me chuckle.
As the proud owner of both a T2 and T4 this Manta experiment has me scratching my head. My preference is less volume and just enough fin to avoid slip and slide. Twin fins delivers stability while affording agility.
This Death star T5 with quad fins looks like a super tanker that will not be turning or carving on a half dollar let alone on a dime.
Color me a Doubting Tomas.
Even so....as a TB fan....I say keep on experimenting Nomas.

[Poobah]

Five times Soulglider wrote:

STILL, its a bitchin' looking experiment, nice job.

I don't think that was intentional. Maybe he was just face down on the keyboard there for a while.

Tomas, back to the McKee style set up on the Manta...are the rear fins farther forward then Bruce's formula? Did you move any of the fins farther up from the tail, because it's a prone board?

[nomastomas]

Poobah - McKee doesn't give fin specs for a p-board, so I had to extrapolate a little. WARNING: What I'm about to say holds true for the TB, and may not be applicable to other p-boards. Also, I'm going to assume that the reader has read McKee's stuff and is familiar with his ideas.

On the TBG4, the wide-point is located where the rider's hips are when in riding position. I tailor the outline for each individual rider according to the rider's height. I learned from the early generation TBs that the shape worked best when the fins were located just behind the wide-point of the outline. When I designed the Manta, I added 4" to the overall length of the G4 and moved the WP up 4" as well. Stretching the outline flattened the curve at the WP, which on the G4 serves as both the WP and as a "hip" or pivot point. So I added a second "bump" in the outline about 12-1/2"" up from the tail. This is where I located the trailing edge of the front fin. (12-1/2" up & 1-1/4" in from rail) (note: McKee's front fin placements are intended for stand-up surfboards and are therefore not applicable to the prone rider).

Next I narrowed the tailblock, since on the longer Manta it only has to be as wide as the distance across the rider's leg at mid-thigh, and not the width of the hips. I flattened the outline curve between the new bump and the tailblock to promote less resistance to turning when on rail. A widely accepted method for placing quad rear fins is to halve the distance of the front fin from the tail. So half of 12-1/2" is 6-1/4". McKee places the rear fins about halfway between the stringer and the rail. On the Manta, the tail is 19" wide at 6-1/4" up from the tail. Half of 19" is 9-1/2" and half of that distance is 4-3/4". Rear fins are set a 6-1/2" up and 4-3/4" in from rail.

Some shapers set fin toe-in by projecting an imaginary line from the fin trailing edge point to a point on the nose. Others set toe-in measuring distance from leading edge to stringer. McKee likes the former, but I like the much simpler latter method. Common practice with quads is to set the front fins at 1/4" toe-in and the rear fins at 1/8". Given that I want more speed an projection from this shape, I set the front fins at approximately 3/16" toe-in and the rears at 1/16". "Approximately" because the margin of error of the measuring tool (Foam-EZ shaper's Square) and the fin box jig is probably 1/16". What I was hoping to end up with is something between 1/4" and 1/8" toe-in front, and 1/8" and 0" toe-in rear. I already knew that I'd be using either a 50/50 foil or a 60/40 rear fin, so the small rear toe-in will fit well.

It is important for me to stress that McKee's formulas are applicable to stand-up surf board, where the rider has his rear foot over the fin array. This, of course, is very different for both the kneeboarder and the p-boarder. The key to fin placement is to understand the location of where the rider applies pressure relative to the craft being ridden. McKee's kneeboard formula does locate the fin cluster further up (in the Australian kneeboard tradition). If you choose to use the McKee formula for a p-board, you will have to do your homework. I should add the McKee formula is more than just fin placements. He goes into great detail discussing fin templates for different conditions and different sized riders, as well as asymmetric fin combinations for riders wanting to fine tune their board for a particular break.

[nomastomas]

SJB - Remember that the Manta is designed for larger waves. Turning on a dime or half-dollar is not near as important as speed, drive and projection down the line. That being said, my preliminary go-out suggested that the board is not "stiff" by any means despite its mini-"mega-platter" proportions. Time will tell...

[soulglider]

hahaha! poohbah is correct.