Finless T-Belly

What works and what doesn't. Share design ideas, references and contacts for paipo board builders.
User avatar
bgreen
Big Wave Charger
Posts: 1232
Joined: Fri Aug 19, 2011 5:17 pm
City: Brisbane
State or Province: Qld
Country: Oz
Contact:

Re: Finless T-Belly

#11

Unread post by bgreen »

Nomas,

Going back to your finless drawings/design.

What does the volume look like if you reduce width to 21"? 23 litres is a lot from my perspective.

From your description, I take it there is no chine between rail and bottom? Is this correct?

How much nose rocker does your design have? You'd lose your nose point forward but would more parallel rails be an option to add more nose rocker?

Bob
User avatar
nomastomas
Big Wave Charger
Posts: 597
Joined: Thu Nov 17, 2011 2:30 am
City: Ojai
State or Province: CA
Country: USA
Interests: Surfing, cycling and fishing
Location: Ojai, CA
Contact:

Re: Finless T-Belly

#12

Unread post by nomastomas »

Its been over a year since the original post, and at that time I said I'd have one built "in a month". Best laid plans...but I'm now revisiting the concept, especially since my "edge-bottom" design begs for a finless approach. More on that later.

To answer your questions Bob: I've found that with the TB design and my body-weight-with-wetsuit of 200lb/91kg (my Patagucci R3 is a good 10lb wet), 23L is perfect for me for conditions up to 6ft face. My earlier p-boards were huge in comparison, and as the TB design evolved, it became smaller and smaller, volume-wise, at one point dropping to 21L. While ride-able, the 21L board felt slower to paddle and slower to rise up on plane, so 23L became my preferred volume. While the formula I use to determine board volume for a customer is based upon my preference, it seems to work for others as well. I do make concessions for experience, water-time and customer preference, and make adjustments accordingly. I have spent a lot of time riding this design, in a wide variety of conditions. I try to encourage my customers to "test drive" one of the TBs I have, whenever possible, to allow them the opportunity to get a "feel" for the design. I've built 10-15 of the G4s using this formula and haven't yet received a complaint that the board was too floaty or corky. With regard to volume, it important to consider the volume distribution and not just the raw number. Most prone-riders equate low volume with ease of duck-diving and rail-sensitivity. Typically (but not always) thinner boards are better in both categories than thicker boards. Looking at a side profile of the G4, you can see that most of the volume is in the rear-half of the board, with a very thin and narrow nose. That wedge-shaped profile is very easy to push under water. Likewise, a cross-section view reveals how the "sloped-rail" of the G4 minimizes rail thickness where the rail meets the water, allowing more penetration than a thick, 50/50 rail.

Correct, no chine on that design, rather the opposite. The use of a concave bottom and a 60/40 tucked-edge rail creates a bit of a hook, a downward angle. Again, when viewed in cross-section you can see how this shape would hold into a wave face better than flat (rail-to-rail) and way better than convex or "V". The double concave in the tail allows for a more extreme angle, while simultaneously managing water flow.

The 48" TBG4 has 2-3/4" of nose rocker and 3/4" tail-rocker, as measured in the traditional manner, i.e. placing a straight edge parallel to the centerline at a point on the bottom, equidistant from the nose and the tail. Typically, for any given design, rocker is increased as length is increased, and vice versa. This curve from nose to tail is commonly referred to as "centerline rocker". But there is also a curve from nose to tail out at the rail. This is called "rail-line rocker", and can be the same or different than the centerline rocker. For example, a flat-bottomed shape like the typical foam bodyboard has the same curve, both at the centerline and the rail-line. A shape with V or concave bottom (or both) will have a different curve at the rail than at the centerline. Outline shape doesn't affect rocker at the centerline, but it does alter the rail-line rocker as the board is rolled over on its rail. This is an important concept to grasp. Surfcraft are complex shapes with a plethora of compound curves. The rider can vary the shape of the surface presented to the water, and therefore its performance, by shifting his weight side to side or front to back. Bob, I'm not sure how to answer your question at this point other than to say I can increase the amount of curve at either end without changing outline curve.
"This is a paipo site...isn't it?"
www.tp4surf.com
User avatar
bgreen
Big Wave Charger
Posts: 1232
Joined: Fri Aug 19, 2011 5:17 pm
City: Brisbane
State or Province: Qld
Country: Oz
Contact:

Re: Finless T-Belly

#13

Unread post by bgreen »

Nomas,

Thanks.

I also started out with one of Larry Goddard's boards and have had four made based on the same design. The first one used Larry's specified thickness. It was a good board but I wanted thinner the latest versions range between 21-23 litre. My bonzer is almost 26.

However, the NoFin I rode for years in all sorts of conditions is 13 litres.
Bells_07_2.jpg
Bells_07_2.jpg (42.29 KiB) Viewed 6727 times
The third photo isn't this board but one similar
NoFin_profile_edited2.jpg
NoFin_profile_edited2.jpg (10.03 KiB) Viewed 6727 times
NoFin_profile_edited.jpg
NoFin_profile_edited.jpg (15.38 KiB) Viewed 6727 times
my board -

They are sturdy boards with solid glass jobs, mine survived a trip over some serious rocks with me attached (not going to use that jump off spot again in a hurry)
NoFin_survives.jpg
NoFin_survives.jpg (55.08 KiB) Viewed 6727 times
These are obviously a very different style of board to yours and those ridden by many others. Everytime you log onto the forum you see that photo of John Galera riding a board just like this. They ride solid, hollow waves. I'm thinking about a smaller wave version that will have more planning speed, without losing too much of that underwater glide that these boards allow. That quest continues.

Bob
User avatar
nomastomas
Big Wave Charger
Posts: 597
Joined: Thu Nov 17, 2011 2:30 am
City: Ojai
State or Province: CA
Country: USA
Interests: Surfing, cycling and fishing
Location: Ojai, CA
Contact:

Re: Finless T-Belly

#14

Unread post by nomastomas »

Yes, very different: Planing hull (G4) vs displacement hull (NoFin). I bet that thing flies! Notice how flat the rear 3/4 of the bottom is. I'm guessing that shortening the length of a board like the NoFin would lessen the planing surface and reduce max speed. My Manta has a tri-plane bottom, and while its fast, it tends to drift more in turns (even with 4.6" fins) than the G4.

Out of curiosity, can that board take the path of the solid arrow in the photo below? I can make that turn on the G4, but not on the Manta.
Attachments
Bells2.jpg
Bells2.jpg (42.38 KiB) Viewed 6724 times
"This is a paipo site...isn't it?"
www.tp4surf.com
User avatar
nomastomas
Big Wave Charger
Posts: 597
Joined: Thu Nov 17, 2011 2:30 am
City: Ojai
State or Province: CA
Country: USA
Interests: Surfing, cycling and fishing
Location: Ojai, CA
Contact:

Re: Finless T-Belly

#15

Unread post by nomastomas »

Here's my take on how bottom contours work, based upon Dick Brewer's thinking.
Attachments
RailProfiles.pdf
(2.52 KiB) Downloaded 215 times
"This is a paipo site...isn't it?"
www.tp4surf.com
User avatar
bgreen
Big Wave Charger
Posts: 1232
Joined: Fri Aug 19, 2011 5:17 pm
City: Brisbane
State or Province: Qld
Country: Oz
Contact:

Re: Finless T-Belly

#16

Unread post by bgreen »

Nomas,

The line that is possible is generally between the two but depends on the wave.

The wave is a lot of fun but not ideal for showing how either board typically rides (the NoFin looking for the hollows and the Goddard a long wall), The tide was lower when I took the Goddard board out, so the waves were a bit better lined up and there wasn't as much turbulence off the rocks.

The NoFin
https://www.youtube.com/watch?v=vTSsxx0CU6g

The first Goddard finless
https://www.youtube.com/watch?v=nbcseXmkYkA

Using fins would have made for more control but I did knock all of John's fins out when he loaned me his three finned board.

Generally, the NoFin gains speed (assisted by momentum) whereas the Goddard has speed off the mark. In waves with more power the waves power gives the NoFin added boost on take-off.

Thanks for the Railprofile doc. With the diagrams, what do the arrows in the wave face indicate?

Bob
User avatar
nomastomas
Big Wave Charger
Posts: 597
Joined: Thu Nov 17, 2011 2:30 am
City: Ojai
State or Province: CA
Country: USA
Interests: Surfing, cycling and fishing
Location: Ojai, CA
Contact:

Re: Finless T-Belly

#17

Unread post by nomastomas »

Great videos! Same rider, same spot, same day (I'm guessing), but different boards...amazing how subtle the differences between the two shapes "appear" vs. how they are experienced. All of our discussions/debates over intricacies of prone-board design would probably baffle the casual observer.

The arrows in my over-simplified drawing indicate the flow of water up the wave face, and the effect of bottom contours on that flow. I intended to add an explanatory caption to the drawing, but never got around to it. The drawing was inspired by a similar drawing in the book "The Surfboard Book: How design drives performance" by Sean McCagh, with input from Dick Brewer, Simon Anderson, Steve Lis and Bob McTavish. Anyone interested in surfcraft design should read this book.
"This is a paipo site...isn't it?"
www.tp4surf.com
User avatar
bgreen
Big Wave Charger
Posts: 1232
Joined: Fri Aug 19, 2011 5:17 pm
City: Brisbane
State or Province: Qld
Country: Oz
Contact:

Re: Finless T-Belly

#18

Unread post by bgreen »

Nomas,

The NoFin & Larry's design vary in a lot of ways, but feel quite different. Here is another of my finless boards:

https://www.youtube.com/watch?v=WlvHCGMeh8U

I'm getting a finbox put in so will be able to ride it finned and finless. It will be board # 3 which I have the choice to ride either finned or finless.

Here is something else. Looks like one of Gus Acosta's boards - but finless: https://www.youtube.com/watch?v=LQzulsVOjII

Bob
User avatar
nomastomas
Big Wave Charger
Posts: 597
Joined: Thu Nov 17, 2011 2:30 am
City: Ojai
State or Province: CA
Country: USA
Interests: Surfing, cycling and fishing
Location: Ojai, CA
Contact:

Re: Finless T-Belly

#19

Unread post by nomastomas »

For me, convex and tri-plane bottoms don't offer the "bite" of a flat or concave bottom, with or without fins. Sure, they go fast and turn, but I don't make as many steep sections with them. And, by "make steep sections" I mean staying high on the face and actually crossing the section, instead of sliding down and then going around the whitewater and back onto the face. You end up in the same place, just a different path. I prefer the high-line, where the speed is found.
"This is a paipo site...isn't it?"
www.tp4surf.com
User avatar
bgreen
Big Wave Charger
Posts: 1232
Joined: Fri Aug 19, 2011 5:17 pm
City: Brisbane
State or Province: Qld
Country: Oz
Contact:

Re: Finless T-Belly

#20

Unread post by bgreen »

Interestingly some wooden boards handle whitewater better because they have less volume. my foam boards get stuck there because they can't project around it well and one just has no bite in such a situation (the 5 fin bonzer ploughs through). These boards generally don't have any real problems with a higher line, it is the flats that can see them lose speed. With a finless board, especially a wooden one I often am more surfing the wave's energy rather than surfing a board which carves a wave face. The surfing as an extension of bodysurfing comes to mind here.
User avatar
nomastomas
Big Wave Charger
Posts: 597
Joined: Thu Nov 17, 2011 2:30 am
City: Ojai
State or Province: CA
Country: USA
Interests: Surfing, cycling and fishing
Location: Ojai, CA
Contact:

Re: Finless T-Belly

#21

Unread post by nomastomas »

After 3yr of playing around with different concepts, I finally pulled the trigger on a couple finless T-Bellys. Dubbed the TBFX, one is round nose and the other a flat nose. Both are wide-point forward, traditional crescent-tail, body board outlines. Bottom contours include concave rail bevel and four-channel V-bottom tail. Should have them glassed and in hand in a couple of weeks. Who knows...there might even be some surf?!
"This is a paipo site...isn't it?"
www.tp4surf.com
flojo
Big Wave Charger
Posts: 101
Joined: Mon May 14, 2012 1:54 am
City: Ventura County
State or Province: california
Country: usa
Interests: bike riding, surfing, music
Location: Oak View, Ca

Re: Finless T-Belly

#22

Unread post by flojo »

Photos please when they come back—look forward to seeing them
User avatar
nomastomas
Big Wave Charger
Posts: 597
Joined: Thu Nov 17, 2011 2:30 am
City: Ojai
State or Province: CA
Country: USA
Interests: Surfing, cycling and fishing
Location: Ojai, CA
Contact:

Re: Finless T-Belly

#23

Unread post by nomastomas »

Just gloss-coated and ready for final sanding. This one is a "Demo" board...wink, wink, nod, nod. Can't wait to get it in the water.
Attachments
Deck view showing outline but not the full-length concave.
Deck view showing outline but not the full-length concave.
TBFX_2Small.jpeg (68.12 KiB) Viewed 5301 times
Bottom showing rail concave-bevel and channels.
Bottom showing rail concave-bevel and channels.
TBFX_1Small.jpeg (57.91 KiB) Viewed 5301 times
"This is a paipo site...isn't it?"
www.tp4surf.com
belly rider
Big Wave Charger
Posts: 111
Joined: Thu Jul 31, 2014 5:33 pm
City: Florence
State or Province: Tuscany
Country: Italy
Interests: A True Passion for Paipo & Kneeboards
Location: Italy

Re: Finless T-Belly

#24

Unread post by belly rider »

Thomas in that second photo showing the underside of the board-- am I seeing those "channels" Greenough style similar to the ones you integrated on my last Plaining Hull kneeboard or is this something different?? Love those channels on the Plaining Hull board you built for me :mrgreen: :mrgreen:
its all about the ride
User avatar
nomastomas
Big Wave Charger
Posts: 597
Joined: Thu Nov 17, 2011 2:30 am
City: Ojai
State or Province: CA
Country: USA
Interests: Surfing, cycling and fishing
Location: Ojai, CA
Contact:

Re: Finless T-Belly

#25

Unread post by nomastomas »

I'm calling that feature "concave-bevel" (CB), and yes, I used it on your kneeboard and on the TBG5. The only difference is that, on the TBFX, I extended it the entire length of the board. That CB really holds in the wave face. On finned shapes, I only use it in the front half of the board, since the fins will provide hold in the rear (and the CB doesn't fit with the rail shape created by the double concave tail) All of these shapes have tail-V, which I find to be essential for turning these wide outlines. BTW, the MPH SUP-turned-mid-shape-MPH that your kneeboard is based on, was last seen in Northern California where its being used as a... kneeboard!! I spoke with the new owner who told me it is working quite well for him, despite that fact that the fin cluster is set too far back for a kneeboard.
"This is a paipo site...isn't it?"
www.tp4surf.com
belly rider
Big Wave Charger
Posts: 111
Joined: Thu Jul 31, 2014 5:33 pm
City: Florence
State or Province: Tuscany
Country: Italy
Interests: A True Passion for Paipo & Kneeboards
Location: Italy

Re: Finless T-Belly

#26

Unread post by belly rider »

Wow so they are using in Northern California a hybrid surfboard as a kneeboard??- no wonder he has a hard time turning it with fin boxes set up for surfboards
Those Australians from the land of Oz have all moved those fin boxes way up front to facilitate turning-- they evolved modern designs to gain maneuverability this way
I am all into that Oz stuff --and especially into your deep V's build into my boards and those owseome channels -- the combo provides just amazing results
its all about the ride
User avatar
nomastomas
Big Wave Charger
Posts: 597
Joined: Thu Nov 17, 2011 2:30 am
City: Ojai
State or Province: CA
Country: USA
Interests: Surfing, cycling and fishing
Location: Ojai, CA
Contact:

Re: Finless T-Belly

#27

Unread post by nomastomas »

Just completed a mixed batch of T-Bellies

Left to right TBFX Round Nose, TBFX Flat Nose, TBG5, TBG5, TBG4
Attachments
Big5DeckSmall.JPG
Big5DeckSmall.JPG (120.22 KiB) Viewed 5278 times
Big5BottomSmall.JPG
Big5BottomSmall.JPG (122.14 KiB) Viewed 5278 times
"This is a paipo site...isn't it?"
www.tp4surf.com
belly rider
Big Wave Charger
Posts: 111
Joined: Thu Jul 31, 2014 5:33 pm
City: Florence
State or Province: Tuscany
Country: Italy
Interests: A True Passion for Paipo & Kneeboards
Location: Italy

Re: Finless T-Belly

#28

Unread post by belly rider »

what a line-up of beautiful paipo's congrats
its all about the ride
User avatar
nomastomas
Big Wave Charger
Posts: 597
Joined: Thu Nov 17, 2011 2:30 am
City: Ojai
State or Province: CA
Country: USA
Interests: Surfing, cycling and fishing
Location: Ojai, CA
Contact:

Re: Finless T-Belly

#29

Unread post by nomastomas »

Going south tomorrow morning to look for some waves to try out the FX. Snapped a couple of photos tonight to show some better views of the FX. I'm really happy with how this shape turned out, despite the absence of fins. I'm eager to see how the channels work (or if they work!)...
Attachments
TBFX_deck_nose view.JPG
TBFX_deck_nose view.JPG (186.88 KiB) Viewed 5266 times
TBFX_foil.JPG
TBFX_foil.JPG (174.71 KiB) Viewed 5266 times
TBFX_Channels_tailView.JPG
TBFX_Channels_tailView.JPG (163.42 KiB) Viewed 5266 times
TBFX_channels from nose.JPG
TBFX_channels from nose.JPG (88 KiB) Viewed 5266 times
"This is a paipo site...isn't it?"
www.tp4surf.com
User avatar
bgreen
Big Wave Charger
Posts: 1232
Joined: Fri Aug 19, 2011 5:17 pm
City: Brisbane
State or Province: Qld
Country: Oz
Contact:

Re: Finless T-Belly

#30

Unread post by bgreen »

Good to see it has materialised. It may take a bit getting used to. If it's like my finless boards, it goes better when it's hollow.

The finless feeling can be a lot of fun.
Post Reply

Who is online

Users browsing this forum: No registered users and 40 guests