K4 Ezzy Asymmetrical fins

I cant fault the production fins that came with my new board. For me focusing on technique in turns is the answer rather than playing around with toe and flex, only my opinion though.

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R1DER said..

Al I should have said "which actual reputable model boards have toe in"
So far
Fanatic quad ?just front fins
and Simmer quad ?just front fins
can you confirm or anyone else that JP and Starboard do a quad with toe in?

Not sure but I think most have started putting toe in. The F2 Barracuda even has toe on the back fins.

Possibly with a quad if you lose 2 fins out of the water, less toe may help not losing the tail since the AoA is bigger so the give more lift (but also more drag and only untill the max AoA is reached). It still gives a strange effect when this happens though which takes getting used to. Especially when going fast and making a classical front foot turn.

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Al McLeod said...

dan berry said..

So they need additional toe in to turn properly?

........ No it's like having crap tyres on a Ferrari.... Geez you are getting argumentative these days aren't you?

Pretty sure a Ferrari comes with damn good tyres straight out the box al.
And yes, I'm gettin old. Been off the water for a few weeks with a sore neck so it's grom hassling time

What, everyone too old to be out on a Saturday night, rather be talking fins!!

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OESaustralia said..

KISS [ KEEP IT SIMPLE STUPID!] we are building sailboards not surfboards. Toe in only adds one thing, drag! This slows the board down in turns making it feel like the fin has more grip and turning power, but the turn is slower and more stalled. Then when you want to plane up quickly or go back up wind against the current that drag is still there!
We want maxium controlled speed for all turning and straight line sailing with a small as possible in line symmetrical fins with a small amount of cant to reduce drag as much as possible in combination with a bottom shape, plan shape and rail profile that all work together to give better onwater performance in a broader range of conditions.Been there and done that before.

I think there are a lot more similarities with surfing. It still is water.
Actually, I was making trifin boards from 1997 up to 2004 with paralel fins (no toe) thinking like you. Then I made a board with the 4wfs. This allows you to turn the fins and change cant as well in minutes. Within a day it was obvious that a certain amount of toe (about 2 deg) was faster and turned better. The biggest difference was DTL, up wind there was not that much difference but toe in was still faster. The testing was partly in WA.

Also the underwater fin footage shows clearly the flow deflection under the board, even going fast DTL. I did put some more tell tales under the board in other footage. And it also shows how the flow deflection changes over the depth so pretwisted fins do make another jump in reducing drag. But just toe in is allready better then no toe at all. Talking about stupid. Why do you think wind turbines (or any propellor or a windsurf sail) have twisted foil? Are they stupid for making it complicated?

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Al McLeod said..

dan berry said..

So they need additional toe in to turn properly?

........ No it's like having crap tyres on a Ferrari.... Geez you are getting argumentative these days aren't you?

Ha ha I've tried K4 fins years ago (16 and 17cm) and it was like having crap tyres on a Ferrari They're fat and slow and the foils were lumpy and wavey. Maybe they've improved them over the last few years.

Hmmm interesting. The k4 fins don't do that though, they just change the angle. It's good to see people experiment though. What's the theory with the pretwisted one? Wouldn't that slow you down during the times when your not actually turning?

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Witchcraft said..

northy1 said..

FYI the Fanatic Quad 2014 are measured and confirmed @ 0.7 toe....so ive bought 2 degree offset...will see / might be too much?

My rough guess looking at those fins is that around 3 to 3.5 deg would be ideal.

....just curious....Why do you say that Bouke?

Do they have additional flex under load or are they locked in at that twist?

Total happy with the speed and control of small in line quad fins [ 6 cm fronts 13 cm back ]

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dan berry said..

Does that show it twist straight at speed??

Look at the "horizon" of the water. Port tack conditions. So the first pic is a top turn. I had to take care not to sail through foam in the water so was sailing more on the shoulder to get better images and the wind was light, non planing so could not put a lot of power in the top turn. The second pic is going straight without load on the fin.

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OESaustralia said..

we are building sailboards not surfboards. Toe in only adds one thing, drag! This slows the board down in turns making it feel like the fin has more grip and turning power, but the turn is slower and more stalled. Then when you want to plane up quickly or go back up wind against the current that drag is still there!

Yep this is what I have found with quads.

Why is it twisted under load and straightens when not loaded? Shouldn't it stay twisted when there is no load as it's shaped to do?

Finns are good. The sweedes are hotter