My new finless board

What works and what doesn't. Share design ideas, references and contacts for paipo board builders.
soulglider
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Re: My new finless board

Unread post by soulglider » Wed Apr 01, 2015 9:24 am

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STOP! with the fvking vacuum rail! this is getting stupid.

i meant the square rail not the 1" fat boogie rail, sheeesh. but, obviously whatever you call the "vacuum rail" it works. but, on a different note, certain rails and concaves do grab onto the water or feel like they grab onto the water. grab feels like suction. is the runner fast? quick? flying? maaaaaan! try dropping straight in on a 24" totally flat paipo and pull up on a rail, you have to be a monster strong guy, it feels like its suctioned to the face of a wave.

Now dig this errrrrrrr modern surfcraft; "Tom Wegener has taken the "less fin argument" a few steps forward in his almost finless chined vacuum creation.

Tom Wegener, shaper of the year in Australia, says he got the idea from the rails on a boogie board with "chined vacuum rails."
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SURFFOILS
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Re: My new finless board

Unread post by SURFFOILS » Wed Apr 01, 2015 8:49 pm

There's no need to be rude to me, you made a sweeping statement about all Surfcraft and I responded with a clear and sensible explanation from various aspects.
You tell me to stop talking about Vacuum Rails and then you immediately post a pic of....Chined Vacuum Rails.
Bizarre !

These are a few of the finless board I ride, the totally flat paipo I rode yesterday doesn't suck to the water as it has no concave or effective rail, it sticks to the water becuase it is very flat and very wide. There's no suction or vacuum with thin rails, people used to think that thin rails ' cut' into the wave and created grip but that theory was debunked in the early 70's.
The best part about the Wegener I ride is the chined hull like on Bobs board, combined with the rolled deck it allows the rider to apply body weight During a turn and the reduced volume due to the deck roll and hull chine allows the board to roll smoothly into the wave , displacing water, giving even control and creates drag on that side as the board continues to displace water. The further you lean the deeper the rail sinks and the greater the drag on that side.
The tucked rail on the Wegener assists that by further reducing the volume along the rails.
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Re: My new finless board

Unread post by CHRISPI » Thu Apr 02, 2015 5:59 am

To get a better understanding of water flow around rails, concaves and so-called vacuum rails, check out (images for Coanda effect) on Google, Urban legens like vac rails seem to pass into our vocablery with no scientific bases

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Re: My new finless board

Unread post by Atlantasurfer » Thu Apr 02, 2015 6:10 pm

Surffoils,

What is the story on that thick blue green board? I don't think I have ever seen anything quite like it.

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Re: My new finless board

Unread post by SURFFOILS » Fri Apr 03, 2015 5:17 am

Just an experiment to see how a radical change in thickness/ bouyancy would affect performance.
100mm thick in the middle dropping to 10 mm around the perimeter.
Paddled well, caught waves well but when you tilted the thin rail into the wave it sank too quickly, bogged.
The pressure gradient is a line where the weight/ forces from the rider are focussed under the board.
E.g. stand evenly on two feet and both feet carry the weight evenly but lean to one side and you can feel the pressure has shifted to that side even though everything else is the same.
Same with that board. The loss of volume around the perimeter allowed the rail to sink very quickly. Too quickly.
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Re: My new finless board

Unread post by nomastomas » Fri Apr 03, 2015 12:07 pm

Does that "too thin a rail" apply to plywood paipos?
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OG-AZN
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Re: My new finless board

Unread post by OG-AZN » Fri Apr 03, 2015 1:14 pm

^ Good point & question. In my experience, "too thin a rail" def doesn't apply to ply paipos. My boards are 1/2-5/8" thick ply to start and I like angled "knifey" rails. I make my rails extremely thin near the tail. Even though lots of people say rail shape makes no difference on a ply paipo, I find it's easier to spin and maneuver a board with thin angled rails vs square, reverse, rounded, etc. I've tried them all.

I suppose you could argue whether the thin edge of a ply paipo is acting more like a rail or a fin (skeg). I think that old letter from John Kelly made reference to the rear third of the paipo that usually contacts the wave face being like a fin.

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Re: My new finless board

Unread post by bgreen » Fri Apr 10, 2015 5:55 am

To go onto a related tangent.

Chine or not to chine. The current board has a chine. I'm toying with doing away with the chine or reducing the angle, so it is a bit flatter.

I surfed the board in a variety of conditions and am thinking of a making it an 1" wider (for planning speed) and slightly thicker rails (largely to add some stability when in the tube). It's not that it can't hold an edge but I think generally, there is more stability in such situations.

In shorter period waves, it was harder to paddle into the waves unless there was a nice peak to add some launch. It definitely shined more when there was some power.

I used finned boards with more float for longer paddles or when I thought it would be harder to get into the waves.

Bob

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Re: My new finless board

Unread post by krusher74 » Fri Apr 10, 2015 12:44 pm

bgreen wrote:To go onto a related tangent.

Chine or not to chine. The current board has a chine. I'm toying with doing away with the chine or reducing the angle, so it is a bit flatter.

I surfed the board in a variety of conditions and am thinking of a making it an 1" wider (for planning speed) and slightly thicker rails (largely to add some stability when in the tube). It's not that it can't hold an edge but I think generally, there is more stability in such situations.

In shorter period waves, it was harder to paddle into the waves unless there was a nice peak to add some launch. It definitely shined more when there was some power.

I used finned boards with more float for longer paddles or when I thought it would be harder to get into the waves.

Bob
Do you have a pic of the tail of the board end on would like to see the rails and hull exit shape/concave ?

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Re: My new finless board

Unread post by Uncle Grumpy » Fri Apr 10, 2015 7:15 pm

krusher74 wrote:
Do you have a pic of the tail of the board end on would like to see the rails and hull exit shape/concave ?
Yes please. And maybe a length wise rail shot as well.
Paipo surfer in repose,
Nose on the nose,
No grunting he-man pose.
See how fast he goes!
What is it he knows?

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bgreen
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Re: My new finless board

Unread post by bgreen » Sat Apr 11, 2015 3:28 am

Krusher & Uncle G,

if this isn't what you wanted let me know. You need to scroll down the first photo to get the full view.

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Looking Downthe Tail
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Bob
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Tail
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krusher74
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Re: My new finless board

Unread post by krusher74 » Sun Apr 12, 2015 4:14 am

cool 8-) , have they used some of that vector carbon on the rails? and if so what was the thinking behind that?

I was really interested in an tail end on shot like this
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bgreen
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Re: My new finless board

Unread post by bgreen » Sun Apr 12, 2015 4:35 pm

Krusher,

Is this clear enough? Due to thinness and some reflection it may not be clear enough to make out the details. The build was a bit of a mystery. I was told it was built in 4 stages, with the rails done last. Epoxy infused wood. The basic aim was thin but strong.
Tailend.jpg
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Bob

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