If I understood Brett’s discussion correctly, the turbulence at the base of the fin renders that area of the fin ineffective – reducing actual useable fin area by the thickness/height of the turbulence layer, 25-35 mm up from the base of the fin.
In my experience surfing these waves this does not exist and the opposite exists .
The Falcon
Foil file: http://hrobeers.be/finfoil/foil/faad13b8d25b3cc3821ba548f9c3c0cf8b9490f0_falcon.foil
STL file: http://hrobeers.be/finfoil/stl/faad13b8d25b3cc3821ba548f9c3c0cf8b9490f0.stl
OpenSCAD code:
translate([20, -20, 0])
scale([300,300,300])
import(“C:\Path\To\File\faad13b8d25b3cc3821ba548f9c3c0cf8b9490f0.stl”, convexity=3);
Tools:
eefett
Tguhhiu…hung
Every thread an adventure
With a template like this sized and placed correctly you will have a well controlled lifting body effect below your board .
A very interesting feel and could see these being very sucessful in the market after developing them fully .
Surffoils, I think if you do the whole thing out of a piece of 1/4" G10, you won’t have to worry about when to attach the posts.
fun project you have going there!
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these fins looks realy nice and I love the idea!!
Can you (or anyone else ;-)) please give some hints how do you vacbag them? One work step? Several work steps? Do you use peel ply?..?
Regards, Andi
Has anyone done anything with this shape?
I made a couple years and years ago, as a single on a longboard. They both snapped (rather inevitably), but had an exciting flex and twang.
I’ll bite; could you please tell us/explain to us a little more about that comment Greg?
What position do they drag? And why? What kind of a drag is it? Is it a bunch of different kinds?
Is it all of the fins, or only just one or a maybe few of them (e.g. have heard/read about the effect of the shockwave from the forward rail fins on the centre trailing fin if it’s positioned in the wrong spot).
And why is it that the most efficient position is only a teeny bit forward of where they start to “drag”.
What about the sizing? What is it that causes a slight increase in “size” to change these fins from “drag-free” to “dragging”? Why are they “drag-free” in the first place? Is it a particular aspect of size? E.g. total surface area? positioning of surface area? foil thickness? foil shape? etc.
Cheers.
I’m interested in Greg’s theory too.
Shockwaves only appear in supersonic flow. Since the speed of sound in water is higher than in air, imagine the speed you need. So don’t believe that theory.
However, a bow wave while planing is mathematically equivalent to a shock wave. (Planing is mathematically equivalent to supersonic flying). But that has to do with the speed of surface waves, not sound waves.
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Thank you very much for this detailed description of your process!
Do you also vacbag the outer sides when the fins are foiled?
After foiling, With the veneer laminated fins I just give them a single resin coat , light sand , polish a bit.
They’re plenty strong and don’t need extra glass.
Chew on this one boyz…
All the variants of templates, foils, cant, and toe-in count big time so does graduated flex modulus.
We all have theories to persue. So many variables we’ll never get it all done but the journey is certainly worth it.
A final note: The canard is big time performance asset. The Trailkill secret fin is a gem IMHO.
Stay Stoked, Rich
Www…goid
What’s next indeed. I’m going to build what’s next, as a personal board, that will also be used as a demo. 7’ x 22’’ NOT a duck diver! Also not for groms, though it can easily be scaled down. I’m considering a fin configuration that allows 2, 4, or 6 fins in use. The ‘‘cluster’’ will NOT look like any grouping now in use. At least to my limited knowledge. Do you find something like that interesting? No need to answer, I’m not trying to hijack the thread, or topic. You, Surffoils, are doing something very interesting. Many parties are watching. So, charge on !
There’s two main reasons to make fins…for better performance or to make money… it’s not either/or , it’s usually a combination of both . Making a really nice one-of fin(or set of fins) is not so hard , if you have some understanding , and can sand a good foil . Producing a good production fin , that’s viable in the market is another ball game. Through necessity , I have been confronted with creating a system to produce wooden fins that are viable to produce regularly with the use of CNC foiling…I know the required outcome , but the process is throwing me some unexpected curves that I didn’t see coming…(lol)… a good set of hand made fins is absolute gold… if you get the chance , grab them , regardless of the price.
+1
Good seeing you posting again, Rich. Hope you’re doing well.
