TBG5

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TBG5

Unread postby nomastomas » Tue Aug 08, 2017 2:14 pm

After months of designing and re-designing, I've come up with the latest iteration of the T-Belly. This one is heavily influenced by a kneeboard I built for BellyRider, which in turn was influenced by a progressive SUP design I did for the guys at Melody Surfboards in Greece, and 7-8 Mid-size shape that I’m now riding. All the above would fall into the "modern planing hull" school of surfcraft design. Nothing that hasn't been done before, just my interpretation, in this case applied to a prone board. The dimensions of this G5 are 49" x 22-1/2” x 2”-2-3/8” 23.5L.
The most obvious (and only) change in the outline is the diamond nose. I normally ride a 48" G4, but for a variety of reasons, I found myself on a 49" G4 for the past several months. I enjoyed the added length of the 49"er but didn't like the stretched reach to the nose when in the paddling position. The diamond shape reduces the reach by a good 1-1/2” at the corners, so we’ll see.
TBG5_web.JPG
TBG5_web.JPG (19.74 KiB) Viewed 1734 times

The bottom has the more obvious changes. Adding a bevel to the rail has a similar effect of adding “V”, namely it changes the rocker curve out at the rail, and assists in getting a relatively wide board over on rail for turning. As I looked at the beveled rail in cross-section, it occurred to me that I might be able to make the rail shape more effective by making that bottom rail-band concave. Looking at the concave bottom rail-band in cross section I could see (in my mind’s eye) not only a better hold into the wave face, but also a means of channeling water flow towards the tail. This concave would also reduce the volume of the rail, producing a thinner rail for better wave-face penetration. (A more effective rail profile may lead to a reduction in the fin area needed to obtain the same hold properties as the G4).
TBG5_Bot01_Web.JPG
TBG5_Bot01_Web.JPG (35.03 KiB) Viewed 1734 times
TBG5_Bot03_web.JPG
TBG5_Bot03_web.JPG (61.3 KiB) Viewed 1734 times

The bottom is otherwise standard G4; convex nose, slight concave in mid-section and dual exhaust tail concaves. I’m starting to thin out the tail of my prone boards a little more. I believe this helps the tail sink on take-off, keeping the board (and rider) more parallel. The board will have quad fin-boxes (of, course) and I designed a small, relatively flat section in the bottom where the fins will be located as a courtesy to my glasser. The board will be finished in 5.7oz carbon fiber, one layer deck and bottom. At this point in the process shaper becomes surfer, and I begin to pester my glasser with “Is my board ready yet?”
Attachments
TBG5_Slices.jpg
TBG5_Rail01_web.JPG
TBG5_Rail01_web.JPG (52.11 KiB) Viewed 1734 times
Last edited by nomastomas on Wed Aug 09, 2017 1:30 am, edited 1 time in total.
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Re: TBG5

Unread postby Pes78 » Wed Aug 09, 2017 12:25 am

That looks like a good time. What blank did you use?
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Re: TBG5

Unread postby nomastomas » Wed Aug 09, 2017 1:28 am

Its 2lb eps from Marko, probably slab cut. Because its stringerless, its just easier to send the file, approximate dimensions and my density requirement, and they do the rest. That way I'm not paying for foam I don't need.
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Re: TBG5

Unread postby bgreen » Wed Aug 09, 2017 4:20 am

Nomas,

When it's glassed I'd be interested to see a shot from the tail looking down.

How wide is the planning area before the concave - 18"?
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Re: TBG5

Unread postby nomastomas » Wed Aug 09, 2017 11:02 am

I presume you mean the single concave that runs down the center. It's 14" wide at the center. The nose belly starts to go concave at 3'4.74" up from the tail. The single starts to go double at the mid-point. All the transitions are very subtle and can be seen best with the CAD software. I forgot to mention that some of the inspiration for the bottom came from George Greenough's "Edge Boards".
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Re: TBG5

Unread postby bgreen » Wed Aug 09, 2017 5:03 pm

Thanks. It was the concave I was referring to.

The raised bottom did remind me of an edge board. Flatter where the single concave is and without the double concave/vee is one of many ideas I had been toying with.
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Re: TBG5

Unread postby nomastomas » Fri Sep 08, 2017 6:08 pm

So...after what seemed like an inordinate amount of waiting (speaking here as a surfer not a shaper ;) ), I picked up the G5 at my glasser's. All I can say is "well worth the wait". I opted for the red accent because the bottom contours, when sheathed in carbon fiber, reminded me of an F1 race car, and the red added to that aesthetic. But red also because I'm growing weary of getting dropped on because people just don't see me coming. The photos below don't do it justice, as the black seems to absorb the shadows necessary to reveal the contours. But, I'm stoked at how the board turned out and can't wait to get it in the water.
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IMG_3058.JPG
IMG_3056.JPG
IMG_3060.JPG
IMG_3064.JPG
IMG_3065.JPG
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Re: TBG5

Unread postby SJB » Fri Sep 08, 2017 8:06 pm

Very cool. If we ever get a swell again let me know where and when. Would love to test drive.
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Re: TBG5

Unread postby CHRISPI » Sat Sep 09, 2017 5:18 am

Very nice love the rails
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Re: TBG5

Unread postby bgreen » Sat Sep 09, 2017 11:37 am

Nomas,

Thanks. The black does make it hard to see the details. It will be interesting to hear how it rides.

Aesthetically, the style of nose doesn't appeal, but if it works, that's the real test. It looks like there is fair amount of rocker in this board.

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