Fins of a New Generation.

A forum for discussing paipo board gear such as swim fins, leashes, skegs (board fins) and other related wave riding gear.
SURFFOILS
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Fins of a New Generation.

Unread post by SURFFOILS » Sun Nov 06, 2016 5:28 am

Fins interrupt the flow under the craft to create drive and drag. You can live without them but they bring their own joy too.
There are many fin designs but they all fall within certain parameters that suit surfing so any new design has to be aware that going 'too far' will make it unworkable or just not enjoyable.
There are some similarities with Aero and Hydro Dynamics and an interesting one is that planes use a thin slat along the leading edge to direct flow over the wing, as the wing increases in angle the slat allows the wing to maintain lift at higher angles.
Translate this to surf fins and you get a two slim fins that overlap. The result is that when you turn the fin doesn't start to drag -it keeps projecting, on a paipo it gets you further down the line like a shortboard, on a shortboard you go further with less effort.
It's still in development but here's a few versions....
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Last edited by SURFFOILS on Sun Nov 06, 2016 5:39 am, edited 1 time in total.
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SURFFOILS
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Re: Fins of a New Generation.

Unread post by SURFFOILS » Sun Nov 06, 2016 5:37 am

And a few more versions. Subtle variations in glass or carbon or 3-D printed.
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Re: Fins of a New Generation.

Unread post by krusher74 » Sun Nov 06, 2016 9:37 am

interesting stuff,

how does a blunt leading and trailing edge effect water flow?

there also appears to be no foil on them? :?

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Re: Fins of a New Generation.

Unread post by SURFFOILS » Sun Nov 06, 2016 2:40 pm

Hi Krusher, I did a lot of easy experiments with flat 3mm aluminium and I would say that performs about Eighty per cent of the function of a fin. For fins under three inches high the Three mm Al is fine. And with no foil every fin is an exact copy and at three mm the leading edge is easily rounded.

Now I'm making more of them I'm moving to six mm marine ply and I'll glass them and start foiling. I sold a few to begin with but now choose to wait until I've got the design worked out fully, the design is so new every version bring new ideas.
They're a bit like F-1 front wings where they layer thin foils over one another to get a strong grip affect.
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Re: Fins of a New Generation.

Unread post by SURFFOILS » Tue Nov 08, 2016 5:43 am

New 6 mm fins, easy to fit into the FCS plugs and they only need leading and trailing edge foil.
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Re: Fins of a New Generation.

Unread post by SURFFOILS » Sun Nov 13, 2016 6:02 am

The best way to test fins is in the surf but I'm building a Flume or a hydrodynamic water channel to test how water flow interacts with fins. It's 8 feet long and uses a pump to provide a smooth but fast flow to see how different fins interact at different angles.
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krusher74
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Re: Fins of a New Generation.

Unread post by krusher74 » Wed Nov 16, 2016 4:54 pm

It would be interesting to see with a flume how concaves, v's and channels effect water flow. (i guess that's what simmons was up to)

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Re: Fins of a New Generation.

Unread post by SURFFOILS » Wed Nov 16, 2016 8:32 pm

The biggest problem is dealing with the massive volume of water coming out of the pump. I stood it in a bucket and flicked the switch and it shot a geyser about 20 feet in the air. Hmmmm....
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Re: Fins of a New Generation.

Unread post by belly rider » Sun Nov 27, 2016 1:07 pm

I am totally stocked on your work
I firmly believe that the future lies in FOILS for fins
I have a collection dating as far back as the Dale Velzy "V" model, to the Ben Laxan design for Cheyen, as well as FCS 3D, the Quantum fin, etc etc
It appears as if the OZ's are ahead in this game and new ideas and developments are coming out from Down Under -- great work
After having tried various options I am Currently surfing with the Quantum fin and the older Ben Laxan model with great results
Not only do they provide some lift that might offset my weight 220 lbs (with 5mm wetsuit) but they just keep you hooked on the wave
In those late takeoffs where you think you just wont make the section these fins just stay HOOKED in the face of the wave and give you the power and drive to make it
where the ordinary fin just appears as it is SLIPPING from under you and loosing grip in critical situations
I might add that in my opinion the foiled fins work out perfect in foamy sloppy conditions where the ordinary fin might not preform as well
Count me in on buying one to try out when you go in production and or are ready to sell me a set to try out
CONTACT david.rigo@email.com
looking forward to hearing from you soon
its all about the ride

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Re: Fins of a New Generation.

Unread post by SURFFOILS » Sun Nov 27, 2016 2:55 pm

Hi David, I'll certainly contact you when they're ready.
Fins are like anything else , they all provide a different experience.and maybe a different fin won't make you into Slater but it will be interesting to ride and give you a different understanding of how fins work. Here's another of my fin designs -The Floating Fin.
Are you interested in the science ?
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Re: Fins of a New Generation.

Unread post by CHRISPI » Fri Dec 02, 2016 9:29 am

Now run that horizontal to give lift!!

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Re: Fins of a New Generation.

Unread post by SURFFOILS » Fri Dec 02, 2016 3:08 pm

That would be interesting , having standard surfcraft fins that rotate into horizontal hydrofoils. :)
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Re: Fins of a New Generation.

Unread post by bgreen » Sat Dec 03, 2016 4:10 pm

Surffoils,

There will be no stopping you with your own backyard flume. Are you trying the fins standing or prone?

There seem to be a lot of potential directions that you are heading. What feels most promising?

Bob

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Re: Fins of a New Generation.

Unread post by SURFFOILS » Sun Dec 04, 2016 3:28 am

The Flume will be good to visualise how the water flows around each design over a range of angles. They all look smooth at 0 deg, but it's at what angle the flow starts to become turbulent and how it then flows that will bring a lot of insight. And all the specialty fof no like the Starfin, the Superchargers, fins with tubercles, close set twin fins,floating fins, tunnel fins...all those other fins that are interesting.

Personally I like both the Twin blade fins and the Floating fins I make, they're both a different experience to ride and after 50 years of surfing , it's great to have Something really different .
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Re: Fins of a New Generation.

Unread post by SURFFOILS » Thu Dec 08, 2016 5:14 am

I'm really caught between spending ( wasting ) my time building either the twin blade or the Floating fin designs.
The Floating concept is the most interesting so I'm sticking with that until I see something shiny that distracts me.
Here's the latest...
My idea is that if I can get the 'fin' away from the hull it can then be its own design, no longer a dorsal shape it can be any shape t all but probabaly more of a 'stand alone unit ' irrespective of convention.
Hers the basic shape, without the base area for drive I've made it more of a longer shape to offset the loss of base. And with the perimeter free I've folded over the top and bottom edges with a 'wingtip' folded towards the stringer. Convention would have the tips folded towards the rail but similar to a Webber CRV fin, the idea is to hold the flow on the inside of the fin for longer, increasing the drive effect.
Here's the paper plan and the foam block that I will vacbag layers of glass, carbon and veneer over.

It's all open for variation but without the first step it's all conjecture.
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Re: Fins of a New Generation.

Unread post by SURFFOILS » Fri Dec 09, 2016 4:49 am

So I've vacbagged layers of glass and veneer over the foam mold and when it's set, pop it off the mold and it's ready to shape. If you put the same number of layers of glass together it wouldn't be as strong as when you separate them with the veneer.
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Re: Fins of a New Generation.

Unread post by SURFFOILS » Mon Dec 12, 2016 6:35 am

Only 4 mm thick but because of the bends it's not going to break.
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Re: Fins of a New Generation.

Unread post by bgreen » Wed Dec 14, 2016 6:37 am

Brett,

Is this last photo the floating fin? No doubt you've already explained it, but what the idea behind this fin and what difference is there in how a board rides?

Bob

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Re: Fins of a New Generation.

Unread post by SURFFOILS » Wed Dec 14, 2016 7:09 am

Thanks for the question Bob, yes it's a 'Floating' fin, the idea is that the base of any fin constantly interrupts the flow along the hull and it adds massive drag, more drag than is needed because you can turn a surfcraft without a fin but we all have these big base fins. However if you lift the fin away from the hull it allows the flow to slide along the hull contours. The Floating fin area still creates drive but with less drag. It's not a pro/ hardcore fin but more of an " Experience" fin. Because the fin is sitting away from the board it's way more stable.
You ride it and say Oh I get it !
If you wanted to do nothing but race along waves as fast and stable as possible this is the fin. It's not slower, just more stable.
I'll work on making it turn and pivot more in the next version.
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Re: Fins of a New Generation.

Unread post by bgreen » Wed Dec 14, 2016 3:06 pm

Brett,

Thanks. Ok, I think I get it now. I suspect if you surfed rocky places there would be a high risk of snapping the bases (I managed to knock out all three of Malaroo's fins at his home break, which is a rock shelf).

Is there much noticeable sideways movement in the fin or is it pretty subtle? Does fi performance change much as the surf gets bigger/hollower?

Bob

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