seabreezer said..

Bouke-Witchcraft said..

DunkO said..
I'll be dammed if I'm reading any of this fin sci-fi dribble. witchcaft boards go bloody good, the whole package, rail rocker and fins. Definitely better than the production boards I've sailed. Planes quicker and rail turns so good. Cross- Onshore was where it was super obvious, and I can't sail onshore at all.

the fancy witchcraft fins in my Quatro do some weird stuff bottom turn at speed on big waves, like eat some major sh!t weird. But turn sick in small slower stuff

assy have to be the go, wavesailors want to surf, no surfboard has straight symmetrical fins.
i recon Bourke is on to something, just felt right on his board, and haven't felt that on my own gear.
you can knock it but it works, but may not be Isolated to fins though.

I was wondering how you were getting on with them. More recently I realised I place the fins closer to the rail (to make more use of the drive effect when the outer fin leaves the water so you can crank it through a turn harder and also to keep grip better when you are hanging in the wall) and that for boards with the fins more in board, maybe could use a 0.2 or 0.3 degrees less. I will change that next time. But as you say, in smaller waves they work well and that is what most people have.But if the wave goes too steep at some point you will lose the tail though:

Bouke ..... bit more CANT ? .... ( i love it - know you would sooner leave vertical forces alone )

I am hesitant to use cant. Around 28 years ago one of the first boards I made here was a single fin for a friend and after a few months he said: There is one thing I dont get, when I sail port tack, sometimes I feel the tail slide out when sailing out but when I sail starboard tack, I get that when coming in. Which is weird so I checked the board and the tip of the 19cm fin was leaning over 3-4mm. Like it had one degree cant. So I replaced the box and everything was fine. From that experience, I prefer to not mix things up. The board is for vertical lift and the fins for horizontal lift (90 degrees to eachother). I think in this video, the crash is because he is getting sucked up the wall because he is trying to get out side ways. Hard to say whether he would have made it dropping down first to get speed and then get out of the way. I think that when the video starts, he is already too far on the bottom and does not get speed from the wave whilst the wave was not too steep yet to do so. In such conditions you have to read the wave well and plan your line ahead, which is not easy and takes a lot of experience and knowing the wave. But, like I said, hard to say whether that would have avoided the crash. Actually my team rider Andy Fawcett from Cornwall wrote me after this video that he had this happen to him as well. This is what he said last week:Hi Bouke Going back to the conversation about the board "slipping" and the clip of the lad in Ireland getting drilled after the board slips I believe that I have cracked it. Or to be more accurate you have cracked it and I have just caught up. I have been using the smallest fins possible. However I have now moved over to 11.5 side fins. At first I went with a bigger center fin. However, I have now switched back to a 12.5 center fin moved fairly far back in the box. It doesn't slip.....not yet anyway. I also have the mast foot further back. So everything is set further back, bigger side fins which seems to give more reliable grip in the bottom turn but still that lose feeling in the top turn. All of this is on the 73 ltr board. Regards Andrew.Hi Andrew, Thanks indeed, you could be right by moving the mast track back. I hadn?t thought of it but if you are going in an angle down the wave and the front rail catches too much, it may want to turn back up the steep wave before you have reached the bottom and until you are really going back up the wave, there will be a moment where the tail could slip. And indeed a bigger side fin helps to keep grip to hang in the wave and help to go down first before you make the bottom. Some images of Andrew from a few years ago:

Doggerland said..
Cant ..
Would be interested in other perspectives/experiences

I have many of the same fins with the same toe bit different cant, which I achieve by moulding fcs base fins into slotbox basees. Standard fcs flat inside fins with between 2 and 6 degrees cant. I prefer around 4 degrees cant on most of my boards.

Effectively, cant does similar things as toe, ie detuning the turn entry. But cant affects how the board reacts to edging, ie putting the board in rail, while toe reacts more to rail engagement, ie how much the board has actually started to turn. With more cant you can run a bit more powerful fin and retain a loose turn entry but access a more powerful grippy turn. So in essence, just as you would predict, more cant shifts the grip towards being generated at higher board angulation angles.

As mentioned though, the adjustment window for me is small. In my typical relatively small wave conditions, I reckon I rail up my boards more than most and yet I tend to stay at or below 4 degrees, even with very large fronts (twin setup)

Back in 2005 with the 4wfs we did do some testing with cant but together with the toe, it becomes quite sensitive to get it right.

This tendency for witchcraft boards to slide down the face in certain conditions really shows the limitations with the fin setup.

a well designed quad is more suited to steep/hollow waves when you dont want to slide down the face and want the choice of a high line.

You want more grip.... quads.. you want the ability to stay attached in high aoa situations... quads

Bouke, I think you have just validated quads in tricky situations.

jontyh said..
Bouke, I think you have just validated quads in tricky situations.

Ah, sorry, I forgot the sarcasm icon after that first phrase.....

Bouke-Witchcraft said..

Let's put this one to bed.

He goes early, doesn't generate any speed, goes back up the face where he catches the clew, this sheets the sail in hard, which means the board can't turn back down the wave and he eats it.
What he could have done is delayed going a second or 2, had more speed, done a proper turn and either aired it or cut back harder with speed.
Or if he insisted on going when he did , he could have pumped his legs to generate the speed he needed to get a turn in, rather than his passive straight legged nothingness getting sucked back up the wave and wasted.
This video has nothing, at all, to do with fins.

( All this said from the comfort of my armchair, you are welcome)

Rango said..
quobbafins.com/pages/technology

Was the twisted fin theory meant to reduce drag, if so these guys say the tip makes little difference , its all in the base.

So, there is a lot of turbulence and drag at the base of the fin? This then is a distinct argument in favour of getting the AOA of the base of the fin correct, so as to minimise the drag.
The twisted fin is then the refinement of the system with toe-in being of primary benefit.
So in fact I would say that your link supports the twisted toe'd in theory not disproves.

sheddweller said..

Rango said..
quobbafins.com/pages/technology

Was the twisted fin theory meant to reduce drag, if so these guys say the tip makes little difference , its all in the base.

So, there is a lot of turbulence and drag at the base of the fin? This then is a distinct argument in favour of getting the AOA of the base of the fin correct, so as to minimise the drag.
The twisted fin is then the refinement of the system with toe-in being of primary benefit.
So in fact I would say that your link supports the twisted toe'd in theory not disproves.

Nope. It doesn't support that at all.

this notion that at 2.1deg or whatever angle, some magic occurs, is ridiculous. I posted the study earlier that showed the angle of attack on the fins swings suddenly + or - 45degrees at the board surface because the water is constantly moving and the board is constantly turning.. That aside, most typical fin foils are comfortable up to 20degrees so 0.1 of a degree will have minimal effect.

The quobba fins study is in reference to the drag that occurs at the fin connection to the board. drag due to the wildly swinging AOA would also be at play. There has also been testing between glass on fins and boxed fins. Glass on fins have fillets which reduce drag where as box fins don't have fillets. Quobba fins have fillets shaped into the fin base. Same reason why some of the delta weed fin makers use fillets on their fins and why planes wings have fillets.

the study into surfboard fins demonstrated the drag difference was low. Off the top of my head 3% or something. Probably not worth worrying about but definitely there. it's addressing drag due to the connection.

toein on fins adds drag. That's the reality of how this works. you guys can argue against that all you want but unfortunately that's how it works. Using asymmetric fins is trying to overcome the drag created by toeing the fins in the first place.

however, toeing fins does improve turning and that's why it's done. A fin has a lift component at 90deg to the meanline of the foil. When the fin is parallel to the board, the lift component is 90deg and holds the board in the wave. By toeing in the fin, it rotates the lift in a direction more towards the nose of the board and that is what makes the board turn better.additionally, by moving the front toed fin more towards the rail and away from the centre fin we increase the pivot. Not sure if fulcrum is the right term. Anyways this is why the relationship of all fins is important. have you noticed wider tails suit multi fin setups.

all of that is not my opinion. I am repeating the findings of many studies into fin design and orientation which are available online. Show me information that counters that and It will change my understanding and from that my opinion.

Gestalt said..

sheddweller said..

Rango said..
quobbafins.com/pages/technology

Was the twisted fin theory meant to reduce drag, if so these guys say the tip makes little difference , its all in the base.

So, there is a lot of turbulence and drag at the base of the fin? This then is a distinct argument in favour of getting the AOA of the base of the fin correct, so as to minimise the drag.
The twisted fin is then the refinement of the system with toe-in being of primary benefit.
So in fact I would say that your link supports the twisted toe'd in theory not disproves.

Nope. It doesn't support that at all.

this notion that at 2.1deg or whatever angle, some magic occurs, is ridiculous. I posted the study earlier that showed the angle of attack on the fins swings suddenly + or - 45degrees at the board surface because the water is constantly moving and the board is constantly turning.. That aside, most typical fin foils are comfortable up to 20degrees so 0.1 of a degree will have minimal effect.

The quobba fins study is in reference to the drag that occurs at the fin connection to the board. drag due to the wildly swinging AOA would also be at play. There has also been testing between glass on fins and boxed fins. Glass on fins have fillets which reduce drag where as box fins don't have fillets. Quobba fins have fillets shaped into the fin base. Same reason why some of the delta weed fin makers use fillets on their fins and why planes wings have fillets.

the study into surfboard fins demonstrated the drag difference was low. Off the top of my head 3% or something. Probably not worth worrying about but definitely there. it's addressing drag due to the connection.

toein on fins adds drag. That's the reality of how this works. you guys can argue against that all you want but unfortunately that's how it works. Using asymmetric fins is trying to overcome the drag created by toeing the fins in the first place.

however, toeing fins does improve turning and that's why it's done. A fin has a lift component at 90deg to the meanline of the foil. When the fin is parallel to the board, the lift component is 90deg and holds the board in the wave. By toeing in the fin, it rotates the lift in a direction more towards the nose of the board and that is what makes the board turn better.additionally, by moving the front toed fin more towards the rail and away from the centre fin we increase the pivot. Not sure if fulcrum is the right term. Anyways this is why the relationship of all fins is important. have you noticed wider tails suit multi fin setups.

all of that is not my opinion. I am repeating the findings of many studies into fin design and orientation which are available online. Show me information that counters that and It will change my understanding and from that my opinion.

Hang on you say toeing fins add drag? why would it do that? It would do that because it is not aligned with the flow aoa. But you also say that the flow aoa swings wildly all of the time, and that 2.1 degree toe angle is meaningless because of that. So which is it? You cannot argue both those things.

sheddweller said..

Gestalt said..

sheddweller said..

Rango said..
quobbafins.com/pages/technology

Was the twisted fin theory meant to reduce drag, if so these guys say the tip makes little difference , its all in the base.

So, there is a lot of turbulence and drag at the base of the fin? This then is a distinct argument in favour of getting the AOA of the base of the fin correct, so as to minimise the drag.
The twisted fin is then the refinement of the system with toe-in being of primary benefit.
So in fact I would say that your link supports the twisted toe'd in theory not disproves.

Nope. It doesn't support that at all.

this notion that at 2.1deg or whatever angle, some magic occurs, is ridiculous. I posted the study earlier that showed the angle of attack on the fins swings suddenly + or - 45degrees at the board surface because the water is constantly moving and the board is constantly turning.. That aside, most typical fin foils are comfortable up to 20degrees so 0.1 of a degree will have minimal effect.

The quobba fins study is in reference to the drag that occurs at the fin connection to the board. drag due to the wildly swinging AOA would also be at play. There has also been testing between glass on fins and boxed fins. Glass on fins have fillets which reduce drag where as box fins don't have fillets. Quobba fins have fillets shaped into the fin base. Same reason why some of the delta weed fin makers use fillets on their fins and why planes wings have fillets.

the study into surfboard fins demonstrated the drag difference was low. Off the top of my head 3% or something. Probably not worth worrying about but definitely there. it's addressing drag due to the connection.

toein on fins adds drag. That's the reality of how this works. you guys can argue against that all you want but unfortunately that's how it works. Using asymmetric fins is trying to overcome the drag created by toeing the fins in the first place.

however, toeing fins does improve turning and that's why it's done. A fin has a lift component at 90deg to the meanline of the foil. When the fin is parallel to the board, the lift component is 90deg and holds the board in the wave. By toeing in the fin, it rotates the lift in a direction more towards the nose of the board and that is what makes the board turn better.additionally, by moving the front toed fin more towards the rail and away from the centre fin we increase the pivot. Not sure if fulcrum is the right term. Anyways this is why the relationship of all fins is important. have you noticed wider tails suit multi fin setups.

all of that is not my opinion. I am repeating the findings of many studies into fin design and orientation which are available online. Show me information that counters that and It will change my understanding and from that my opinion.

Hang on you say toeing fins add drag? why would it do that? It would do that because it is not aligned with the flow aoa. But you also say that the flow aoa swings wildly all of the time, and that 2.1 degree toe angle is meaningless because of that. So which is it? You cannot argue both those things.

I cannot help you further

I could have chosen different diagrams?

ah so just rude now?
nice.
Stay classy Gestalt.

I'm very hesitant to even participate in this thread as it seems to be a kind of ridiculous. But I recently experimented myself and feel like it may help someone else thinking about toe in.

I have recently gotten back into wave sailing after kite surfing for the last 20 years. I've surfed my whole life as well, so I have surfed a million boards of all designs. I want to emphasize that windsurfing to me is purely about ridding waves and not speed.
That said, I bought a 2015 JP Single Thruster a year ago and started riding it in the standard thruster set up. I liked it, but it felt a bit dead in the turns. Nothing bad, but nothing exciting either. A friend suggested I try the K4 Ezzys. Being cheap, I kept not ordering a pair. I also kept reading this thread and to be honest made me want to quite reading forums. But I finally threw down on the Ezzy 3 degree toe fins.

My first time out: "holy ****". They gave the board sooo much more grip. But way more importantly they made the board an actual "thruster"! Remember the reason why we call tri fin boards thrusters is because the excellerate out of the turn. The board felt so much more alive. Again, I can't speak to straight line speed. But I did not notice a degradation in speed on the wave at least. It almost felt like I was surfing faster because I could pump the board better.

So....
I really hope this helps someone thinking about adding toe to a straight box board.
I came home that night and told my wife: "that was the best 50 bucks I've ever spent on windsurfing."
My point would be just throw 50 bucks and see if you like it. If you don't, go back to straight. No big deal.

Masthead said..
I'm very hesitant to even participate in this thread as it seems to be a kind of ridiculous. But I recently experimented myself and feel like it may help someone else thinking about toe in.

I have recently gotten back into wave sailing after kite surfing for the last 20 years. I've surfed my whole life as well, so I have surfed a million boards of all designs. I want to emphasize that windsurfing to me is purely about ridding waves and not speed.
That said, I bought a 2015 JP Single Thruster a year ago and started riding it in the standard thruster set up. I liked it, but it felt a bit dead in the turns. Nothing bad, but nothing exciting either. A friend suggested I try the K4 Ezzys. Being cheap, I kept not ordering a pair. I also kept reading this thread and to be honest made me want to quite reading forums. But I finally threw down on the Ezzy 3 degree toe fins.

My first time out: "holy ****". They gave the board sooo much more grip. But way more importantly they made the board an actual "thruster"! Remember the reason why we call tri fin boards thrusters is because the excellerate out of the turn. The board felt so much more alive. Again, I can't speak to straight line speed. But I did not notice a degradation in speed on the wave at least. It almost felt like I was surfing faster because I could pump the board better.

So....
I really hope this helps someone thinking about adding toe to a straight box board.
I came home that night and told my wife: "that was the best 50 bucks I've ever spent on windsurfing."
My point would be just throw 50 bucks and see if you like it. If you don't, go back to straight. No big deal.

in a NUTSHELL fellas .... thumbs up post .... made my day -

and - sounds like youve just thrown them in and theyve worked way better .... without even shifting fwd / back in box , (if jp prob a mini tutt and fixed position ) , BUT aslo , once you start tweaking (in boards with slot ) - and tweaking in relation with your back strap etc - even more gold to tap into ... good you didnt pay tooooo much attn to some of the opinions on here .... WHat we out there for after all .... ooooh , Im going soooooo fast ..... or ..........FAAAAARK .... I just lamped a lip more vert / harder / faster than ever before ...