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Home made fin

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Created by Imax1 3 months ago, 25 Jan 2022
Imax1
QLD, 3706 posts
25 Jan 2022 7:32PM
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My idea is a cross between a much loved Fangy and a more upright fin .
30 cm high and 17mm at its thickest 5cm up.
Starting with 10mm G10 plate and bogging up to desired thickness .
Covered with 2 layers 4oz glass .
No weed where I sail but it does get shallow .















Shifu
QLD, 1657 posts
25 Jan 2022 8:29PM
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Very thick. Won't that be draggy?

Imax1
QLD, 3706 posts
25 Jan 2022 8:50PM
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Shifu said..
Very thick. Won't that be draggy?



Much thinner than a Fangy , and they work great for a shallow water fin .
I have no idea on how well it will work .

Tardy
4343 posts
25 Jan 2022 6:56PM
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LOOKS good max ..my delta is a similar thickness ..and very slippery and nicer after i filleted it ,seems more grip .
kato thinned the fillet out mid section in another GPS thread ,said it made it better ,Faster i think where his words .

decrepit
WA, 11079 posts
25 Jan 2022 8:06PM
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If you've experienced fangy fins, your whole idea about thickness changes.
It's probably not a speed fin, but otherwise I bet it performs great.

Thickness allows a greater angle of attack, and so a smaller fin. Thin fins have higher drag at greater angles of attack, so you need a bigger fin.
It's all swings and roundabouts, depends just what and where you want the fin for.

kato
VIC, 3117 posts
26 Jan 2022 8:59AM
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Tardy said..

kato thinned the fillet out mid section in another GPS thread ,said it made it better ,Faster i think where his words .


Nah, I just give ''em a polish and drive them. I'll leave the shaping stuff to Fangy and Martin.

fangman
WA, 1075 posts
26 Jan 2022 9:27AM
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Oh snap Imax. I have been toying with the idea of a less rake for when the weed is not an issue as well. I am very keen to see how you go, and if it's a winner I can just copy yours. Just a note on the thickness, the more upright rake will far more efficient in generating lift versus drag, so you might find you can loose some of the beef if the fin is generating enough lift in the conditions in which you are sailing. In the meantime, I am really looking forward to the next progress report.

Basher
410 posts
26 Jan 2022 10:27AM
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decrepit said..
If you've experienced fangy fins, your whole idea about thickness changes.
It's probably not a speed fin, but otherwise I bet it performs great.

Thickness allows a greater angle of attack, and so a smaller fin. Thin fins have higher drag at greater angles of attack, so you need a bigger fin.
It's all swings and roundabouts, depends just what and where you want the fin for.




That's actually not correct.
Fat fins are really slow and are only really of any benefit to beginners with poor technique.

LeeD
3939 posts
26 Jan 2022 11:02AM
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Are we talking about low aspect weed fins here?
Or high aspect blades?
The former needs to be thicker than PB and Tuttle boxes, if they're for lighter winds.

Mark _australia
WA, 21342 posts
26 Jan 2022 11:29AM
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Basher said..

decrepit said..
If you've experienced fangy fins, your whole idea about thickness changes.
It's probably not a speed fin, but otherwise I bet it performs great.

Thickness allows a greater angle of attack, and so a smaller fin. Thin fins have higher drag at greater angles of attack, so you need a bigger fin.
It's all swings and roundabouts, depends just what and where you want the fin for.





That's actually not correct.
Fat fins are really slow and are only really of any benefit to beginners with poor technique.


decrepit said..
If you've experienced fangy fins, your whole idea about thickness changes.


This will be fun

Imax1
QLD, 3706 posts
26 Jan 2022 3:02PM
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Talking about thickness, I got to my 17 mm by fudging averages .
Measured 5cm from base.
A average pointer is around 11 mm thick
Fangy 24cm is around 22mm thick,
Fangy 28cm is around 25mm thick.
Fangys are around 50 deg swept back from vertical. Mine is 30 deg.
Foil section shape is about halfway between a pointer and Fangy.
Putting all this info into my super computer , I came up with this fin , which may or may not be a complete dog .
The love child if a Fangy fu..ed a pointer.

fangman
WA, 1075 posts
26 Jan 2022 1:48PM
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Imax1 said..
Talking about thickness, I got to my 17 mm by fudging averages .
Measured 5cm from base.
A average pointer is around 11 mm thick
Fangy 24cm is around 22mm thick,
Fangy 28cm is around 25mm thick.
Fangys are around 50 deg swept back from vertical. Mine is 30 deg.
Foil section shape is about halfway between a pointer and Fangy.
Putting all this info into my super computer , I came up with this fin , which may or may not be a complete dog .
The love child if a Fangy fu..ed a pointer.


Imax have you got a guesstimate of surface area? 300cm^2 ish perhaps?

Imax1
QLD, 3706 posts
26 Jan 2022 4:21PM
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^^^
closer to 430.

decrepit
WA, 11079 posts
26 Jan 2022 2:23PM
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Basher said.. >>>>That's actually not correct.
Fat fins are really slow and are only really of any benefit to beginners with poor technique.



Yes fat fins at a low angle of attack are slow, but so are thin fins at a high angle of attack.

And when talking thickness, we should really be talking about thickness to chord ratio.
Just thickness doesn't mean much without knowing the chord. That gives an idea of the shape of the foil.
So by fat, I'm not talking about anything over 10%, that's very fat.
So a full on downwind speed fin may be 6 to 7% but it will be slow upwind. A more general fin probably works better around 9%.

It's hard to say what Imax's fin is, but the leading edge front on shot can be very misleading.

Also common concepts change once you get in shallow/weedy water, not only is the water flatter there's also a certain amount of ground effect going on. So you can actually go faster with a less efficient shorter, wider, thicker fin.

Imax1
QLD, 3706 posts
26 Jan 2022 6:14PM
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^^^
Its about 10% at it thickest ratio.

fangman
WA, 1075 posts
26 Jan 2022 5:34PM
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Imax1 said..
^^^
closer to 430.


Should lift like the East German Women's Weightlifting team.

Basher
410 posts
27 Jan 2022 5:08AM
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This is a typical road crash of a thread, where most of the contributors really don't know what they are talking about.
I don't know how to correct this, because my own foil making career was not in windsurfing - although my foils did win a world championship.

On a positive note, anyone can experiment with their own fins and foils, shaping the fin at home, and hopefully you'll learn something.

The real problem comes where you, as a sailor, have poor technique and ability, and then you experiment with home made foils - when really you need to learn to sail better.

This conversation about fat foils being better at low speeds or for a 'higher angle of attack' is a great cover up for poor technique.
Just saying.
There's a really good fin brand who also sell 'fat fins' on the basis that they 'will not spinout'. And those fins are absolute rubbish. (Which is a shame because the rest of their fins are quite good. )

Once you have reasonable ability, on a wave board or on a slalom board, you soon realise that fat fins are really draggy. Our focus is not on spinout or on angle of attack.
We also only use a lot of rake in a fin - for the leading edge - when we are dealing with seaweed or for a down the line waveboard.


My top tip when shaping a fin is to go and see what shape and profile the top guys are already using.

Imax1
QLD, 3706 posts
27 Jan 2022 7:30AM
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^^^
What if your not a " top guy " , and just want to use a big sail in shallow water ?
and besides ,
There are guys that go way faster than I could ever hope for , on a fat fin .

Imax1
QLD, 3706 posts
27 Jan 2022 7:35AM
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fangman said..

Imax1 said..
^^^
closer to 430.



Should lift like the East German Women's Weightlifting team.


That's what I'm hoping

kato
VIC, 3117 posts
27 Jan 2022 8:58AM
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Basher said..
This is a typical road crash of a thread, where most of the contributors really don't know what they are talking about.
I don't know how to correct this, because my own foil making career was not in windsurfing - although my foils did win a world championship.

On a positive note, anyone can experiment with their own fins and foils, shaping the fin at home, and hopefully you'll learn something.

The real problem comes where you, as a sailor, have poor technique and ability, and then you experiment with home made foils - when really you need to learn to sail better.

This conversation about fat foils being better at low speeds or for a 'higher angle of attack' is a great cover up for poor technique.
Just saying.
There's a really good fin brand who also sell 'fat fins' on the basis that they 'will not spinout'. And those fins are absolute rubbish. (Which is a shame because the rest of their fins are quite good. )

Once you have reasonable ability, on a wave board or on a slalom board, you soon realise that fat fins are really draggy. Our focus is not on spinout or on angle of attack.
We also only use a lot of rake in a fin - for the leading edge - when we are dealing with seaweed or for a down the line waveboard.


My top tip when shaping a fin is to go and see what shape and profile the top guys are already using.


Interestingly Fangy is making something that doesn't exist . A fat, short, wide fin that gets you going in 6-10 kts and capable of 38 kts. They don't let go and they put a big grin on ya face cos they're just so much fun to use. Good luck to Imax in having a go at making a fin, I did and I'm better at buying one.

sailquik
VIC, 5810 posts
27 Jan 2022 9:08AM
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Select to expand quote
Basher said..
This is a typical road crash of a thread, where most of the contributors really don't know what they are talking about.
I don't know how to correct this, because my own foil making career was not in windsurfing - although my foils did win a world championship.

On a positive note, anyone can experiment with their own fins and foils, shaping the fin at home, and hopefully you'll learn something.

The real problem comes where you, as a sailor, have poor technique and ability, and then you experiment with home made foils - when really you need to learn to sail better.

This conversation about fat foils being better at low speeds or for a 'higher angle of attack' is a great cover up for poor technique.
Just saying.
There's a really good fin brand who also sell 'fat fins' on the basis that they 'will not spinout'. And those fins are absolute rubbish. (Which is a shame because the rest of their fins are quite good. )

Once you have reasonable ability, on a wave board or on a slalom board, you soon realise that fat fins are really draggy. Our focus is not on spinout or on angle of attack.
We also only use a lot of rake in a fin - for the leading edge - when we are dealing with seaweed or for a down the line waveboard.


My top tip when shaping a fin is to go and see what shape and profile the top guys are already using.



And yet, this fellow is a highly skilled, top sailor and got a 38 knots peak from arguably the fattest fin in existence.

After using it for the best part of a year he says:

"I thought that I would do an update as I've been playing with the FF28 for a bit now.
I've now tried polish v unpolished and although there wasn't much speed difference the polished felt slipperier and I would probably continue with the shine.
This fin was designed to get me to 30kts in 8/10 kts which it does but I'm finding the I'm using it more and more in stronger winds. (20Kts with a 7.7) Its opened up some areas that we don't sail cos its just too shallow. Yesterday was a perfect example as I could explore the shallow areas as the rest were still playing on the edge in the chop.
The rake also means that when you hit something its not so brutal. I unfortunately hit a large stingray at 25kts, not so good for the ray but I didn't crash. Hopefully it survived.
No issue with chop either which was a surprise, It reconnects really when bouncing out of the waves, yes I took it for a play into the surf. Small waves.
Look forwards to returning to Lake George and chasing some higher numbers with this fin now that I had some solid sessions with it."


As always, it's horses for courses.

John340
QLD, 2566 posts
27 Jan 2022 9:31AM
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Basher said..
This is a typical road crash of a thread, where most of the contributors really don't know what they are talking about.
I don't know how to correct this, because my own foil making career was not in windsurfing - although my foils did win a world championship.

On a positive note, anyone can experiment with their own fins and foils, shaping the fin at home, and hopefully you'll learn something.

The real problem comes where you, as a sailor, have poor technique and ability, and then you experiment with home made foils - when really you need to learn to sail better.

This conversation about fat foils being better at low speeds or for a 'higher angle of attack' is a great cover up for poor technique.
Just saying.
There's a really good fin brand who also sell 'fat fins' on the basis that they 'will not spinout'. And those fins are absolute rubbish. (Which is a shame because the rest of their fins are quite good. )

Once you have reasonable ability, on a wave board or on a slalom board, you soon realise that fat fins are really draggy. Our focus is not on spinout or on angle of attack.
We also only use a lot of rake in a fin - for the leading edge - when we are dealing with seaweed or for a down the line waveboard.


My top tip when shaping a fin is to go and see what shape and profile the top guys are already using.



Or try and develop something new. The basis of Imax1's proto is the Fangy fin. Fangy fin's design is based on an application of hydrodynamics to solve a shallow water / thick weed windsurfing problem. The following is Fangy's own dissertation on the theory behind his design.

www.seabreeze.com.au/forums/Windsurfing/Gps/FangyFin-MkII-Theory-for-insomniacs?page=1

GPS windsurfers at weedy shallow locations in Australia have achieved around 40kts 2 sec speeds on these fins, so they work.

decrepit
WA, 11079 posts
27 Jan 2022 10:42AM
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Basher said..
This is a typical road crash of a thread, where most of the contributors really don't know what they are talking about.


As I initially said, once you use a fangy fin in shallow weedy water, your whole idea of thickness changes.

Your, ideas are obviously correct for deeper water, when a high aspect ratio fin works very well even if it's raked to 45 deg. But a low aspect 50 to 55 deg fin is a different matter, especially when you sail it fast in chop!
And a lot of our shallow weedy areas, have to be accessed through choppy water.

When I say shallow weedy, I mean WEEEDY! Fangyland can almost look like a bowling green, with long weed growing on the bottom, all the way to the surface. There's no way a "normal" fin will work there.
As sailquick says, it's horses for courses.
You have to have tried a fangy fin in these conditions to be able to comment on them.

fangman
WA, 1075 posts
27 Jan 2022 11:26AM
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Basher said..
This is a typical road crash of a thread, where most of the contributors really don't know what they are talking about.
I don't know how to correct this, because my own foil making career was not in windsurfing - although my foils did win a world championship.





Hey Basher I think I have the solution to correct all the contributors. Can you please:
1) Out of respect to the OP open a new thread.
2) Use your foil making experience to further the sport by posting your design, preferably a proven one that is out in the wild, that satisfies the criteria of:
- be safe to use in water that is say 40 cm deep.
- be safe to use in chop.
- be safe to use in very heavy weed growth that is both bottom growing and surface wrack/debris/macroalgae.
- be strong enough to cope will inadvertent impacts, touch downs and weed abrasion.
- behave predictably in all water states.
- be able to generate enough lift at relatively slow speed to counteract the lateral forces generated by a sail of say 8.0m.
- and thereby allow a sailor of say 100kgs on a 120 litre board to be up and planing, with good upwind ability and at least twice wind speed capability downhill in light conditions.

As a community with the aim of enjoying waters that present the above challenges, and have in the past built on each others ideas, I am sure I speak for us all when I say that your knowledge will be gratefully received and used by all of us to improve our designs. Thanks in advance for sharing and helping improve everyone's experience on the water.

firiebob
WA, 3063 posts
27 Jan 2022 11:44AM
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Nice work Imax1, should be a nice safe shallow water fin

Fangy fin playground

decrepit
WA, 11079 posts
27 Jan 2022 7:54PM
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YES!!! Nice one Bob, that's what fangy fins are all about.

Subsonic
WA, 2560 posts
27 Jan 2022 9:14PM
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Basher said..
This is a typical road crash of a thread, where most of the contributors really don't know what they are talking about.
I don't know how to correct this, because my own foil making career was not in windsurfing - although my foils did win a world championship.

On a positive note, anyone can experiment with their own fins and foils, shaping the fin at home, and hopefully you'll learn something.

The real problem comes where you, as a sailor, have poor technique and ability, and then you experiment with home made foils - when really you need to learn to sail better.

This conversation about fat foils being better at low speeds or for a 'higher angle of attack' is a great cover up for poor technique.
Just saying.
There's a really good fin brand who also sell 'fat fins' on the basis that they 'will not spinout'. And those fins are absolute rubbish. (Which is a shame because the rest of their fins are quite good. )

Once you have reasonable ability, on a wave board or on a slalom board, you soon realise that fat fins are really draggy. Our focus is not on spinout or on angle of attack.
We also only use a lot of rake in a fin - for the leading edge - when we are dealing with seaweed or for a down the line waveboard.


My top tip when shaping a fin is to go and see what shape and profile the top guys are already using.


Ah yes, i see.
Once we've all reached PWA status, we can start discussing fin shape with our scientifically based opinions and proven experiences carrying some sort of weight.


but by then we'll all be on thin profile fins with 36 inch harness lines, and be capable of holding a perfect stance 100% of the time, so we'll all be in agreement about fin profile anyway.


carry on.

LeeD
3939 posts
28 Jan 2022 12:35AM
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Old daze, even the thickest weed fins would stress fracture along the base after part of a season of use. Hence thickness at base.

Tardy
4343 posts
28 Jan 2022 3:01AM
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Subsonic said..

Basher said..
This is a typical road crash of a thread, where most of the contributors really don't know what they are talking about.
I don't know how to correct this, because my own foil making career was not in windsurfing - although my foils did win a world championship.

On a positive note, anyone can experiment with their own fins and foils, shaping the fin at home, and hopefully you'll learn something.

The real problem comes where you, as a sailor, have poor technique and ability, and then you experiment with home made foils - when really you need to learn to sail better.

This conversation about fat foils being better at low speeds or for a 'higher angle of attack' is a great cover up for poor technique.
Just saying.
There's a really good fin brand who also sell 'fat fins' on the basis that they 'will not spinout'. And those fins are absolute rubbish. (Which is a shame because the rest of their fins are quite good. )

Once you have reasonable ability, on a wave board or on a slalom board, you soon realise that fat fins are really draggy. Our focus is not on spinout or on angle of attack.
We also only use a lot of rake in a fin - for the leading edge - when we are dealing with seaweed or for a down the line waveboard.


My top tip when shaping a fin is to go and see what shape and profile the top guys are already using.



Ah yes, i see.
Once we've all reached PWA status, we can start discussing fin shape with our scientifically based opinions and proven experiences carrying some sort of weight.


but by then we'll all be on thin profile fins with 36 inch harness lines, and be capable of holding a perfect stance 100% of the time, so we'll all be in agreement about fin profile anyway.


carry on.


My slalom boards have PWA on them ,does that count i wonder how much over -all thickness a foil would have ,that seem to kick arse vs a fin in moderate winds ,

LeeD
3939 posts
28 Jan 2022 4:04AM
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Once coveted Third World Reasearch weed fin by Steve Roger are exactly 11mm thick, same as Meritex box.
Yes,they show signs of stress factor after maybe 40 days.
My Tetonics Phoenix 32 is fine at 8 days, but it's 35 sibling shows delam at around 30 days of use on a '18 Tabou Speedster.

Basher
410 posts
28 Jan 2022 5:20AM
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kato said..


Interestingly Fangy is making something that doesn't exist . A fat, short, wide fin that gets you going in 6-10 kts and capable of 38 kts. They don't let go and they put a big grin on ya face cos they're just so much fun to use. Good luck to Imax in having a go at making a fin, I did and I'm better at buying one.






It would indeed be great if that were actually true. Obviously, it's not the fin that gets you going on a windsurfer, it's the right combination of power, float and rockerline, directed by sailor technique..
Presumably, if it were true that a fin can get you going in 6-10knots AND speed you to 38knots, then we'd see similar gear being raced at top levels. Most good gear or innovation gets copied immediately.

I thoroughly support the idea of anyone making their own fins, or re-shaping old fins to up-cycle them to a new use.

But fat fins are slow and will feel so to anyone with ability to gybe. Intermediates who aren't at that level might find that thicker fins are forgiving for spinout - when better technique is really the answer to spinout issues.

It is true that a raked back fin helps a lot in ditching weed - and may be essential kit for weedy waters. But the performance of any weed fin sucks in normal conditions.


A fin does not have to be fat at the base for better strength. If your fin is breaking in a standard box, then it's usually the laminate at fault.


Thanks for all the comments in response to my casual remark added to this thread earlier. I just feel it's important to tell the truth about stuff on a forum where newbies come to pick up ideas, and to learn.



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"Home made fin" started by Imax1