TBG5 Step Up

[nomastomas]

With bigger waves theres always the issue of too much speed. A smaller board generates more drag than a bigger board. It has less planing area and is more susceptible to leg drag. The added drag counters the extra speed generated by more powerful waves. Most experienced p-board riders have experienced the skipping stone phenomenon where speed and planing surface combine to generate excessive lift. I'm very concerned about this with the TBX and hope that I can modulate max speed by increasing fin size. The quad-fin set up is very helpful in accomplishing this.

I agree with the wax assessment. I use a little on the back third of my board and an inch or so across the nose for hand grip. Use less in cold water when wearing a wetsuit.

[Cuttlefish]

Let me know when you want to sell it.
Look forward to hearing the ride reports first of course.

[nomastomas]

FedEx just delivered my new logos, so off to the shop. Just a few more days and I'll have a ride report. Surf has been great this month, with more NW on the way.

[nomastomas]

Bob - here's a good shot of the bottom contours before lamination, and a screen grab of the foil from Aku. The bottom contours a more subtle than what appears in the photo due to the shaping room lights. There's also some distortion from the iPhone camera making the bottom look more curved, front-to-back, but you can see the progressive change in bottom contours from belly, to tri-plane to "V". Not easy to do in such a short shape. The foil picture shows the profile along the centerline (Black line) and the profile out at the rail (Red Line). Notice the difference in the rocker curve between centerline and rail. This design provides a flatter speed-rocker when paddling or going across the face, with much more curve when on rail to facilitate turning. The board is 1-5/8" thick at centerline and 2" thick at the rail. This is truly a shape that has to be held to appreciate all the nuances of contour.

[nomastomas]

"Something wicked this way comes" Introducing the "Manta" a.k.a TBX. I'm really pleased with how this design turned out, but you be the judge...

[nomastomas]

More pix...

[flojo]

Hey Thomas...cool looking shape! Ride report when u get a chance

[soulglider]

rad, looks like a devils purse...

[Uncle Grumpy]

DARTH PAIPO

[nomastomas]

Took it out today in lumpy, 2'-3' leftover groundswell (couldn't wait for decent waves). Bottom makes for fluid, buttery smooth turns, but needs deeper fins to get the best traction. Started with 4" asym-foiled front and 3.8" 50/50 foiled rears, but finished with 4.7" fronts and same 3.8 50/50 rears. The Manta paddles well and at 26L, is still very easy to duck-dive. Compared to the G4, the Manta turns smoother, not as twitchy. Just the feel I want in bigger waves, nice smooth carves. I need to try using asym-foiled rear fins to determine how much of the "smoothness" is attributed to the fins and the fin set-up, and how much to the tri-plane-to-V bottom. Finally, extra length didn't seem to make significant improvement in leg drag reduction. But, I could feel improvement in glide, especially in the larger set waves. Bottomline: so far, so good. Need some 5'-6' surf to really see what she's got...

[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]

.

[soulglider]

.

[soulglider]

.