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  1. #834
    Senior Member Witchcraft's Avatar
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    Quote Originally Posted by basher View Post
    That is such dodgy science.
    You are sounding like Farage saying: We´ve had enough of experts. Sorry but I´d rather not get into an airplane designed by you nor would I go to see you if I would need a doctor.

    Quote Originally Posted by basher View Post
    For sure, a board 'parts the water' as it moves through it, a bit like a snow plow, when at slogging speeds.
    But we also a) travel at various speeds, b) have a sideways load on the board which means we also crab sideways most of the time.
    Yes, my dear, but these things are just added on. Just like when you´ve got wind and then when you´ve got speed, that is added on to get your apparent wind. So when the board parts the water, this does not stop just because you go faster or because you add a side ways load. These effects are just added on. All fins are mounted in the board so if you push on the board, you push the same on all fins. You are right we are not able to adapt the fin angles during sailing to different speeds but we can take the average speed and set it up the best to that. You can´t just "dismiss it all" because it varies and that complicates things.

    There are ways to decrease the negative effects of not using toe-in or pretwisted fins but that limits your possibilities and does not help us in progression and development. You are like the climate change deniers. Scientists (you know those people who´ve dedicated their lives to research something for the benefit of all) say it is happening and it is pretty clear to most it is happening but still there are people who for whatever reason or agenda will deny it. Off course you can deny it and keep on living but the process keeps on going at some point you are going to run into it.

    Quote Originally Posted by basher View Post
    1) A lot of bullshit is talked about toe in.
    Yes, there are some people who haven´t got much of a clue who keep on giving advice.

    Quote Originally Posted by basher View Post
    2) Windsurf fin sets up are not like surfboard or SUP fin set ups, because our boards are wind-powered before they are wave-powered. The sailor then drives the board, using the power of the rig as leverage.
    3)What works well for turning on the wave face may not work so well when planing out, a the straight line, or for early planing.
    It is very much like a surfboard, the sideways forces are just added on. So you can very much look at surfboards and then just cater for the higher loads and side ways loads.

    Quote Originally Posted by basher View Post
    4) A lot of brands do not in fact use toe in for their fin boxes – nearly ten years on from when this discussion first started – as they have tested their own designs to find that there is no benefit adding toed-in boxes with some shapes.
    4) People continue to argue the benefits or otherwise of toe in and it goes nowhere because what one person finds for his sailing at his local spot is not transferrable to another sailor sailing at another spot.
    5) On the plus side, you can experiment if you want to nowadays, by buying alternative fin sizes and with side fins available which increase toe-in angle. I have a box of them, which I wasted my money on, to no effect.
    Like I said, there are ways to decrease the negative effects of not using toe-in and when you would experiment with toe-in, lots of other things change as well so you have got to rethink-redesign everything. If you give up right there and then because you want instant satisfaction (or instant profit), that is your problem. I wonder what would have become of the world if any scientist had given up after the first experiment. You would not be windsurfing nor in South Africa now. Toe-in development for sure is a very minor development but they did not built the planes we have now right away.

    Quote Originally Posted by basher View Post
    I'm in Cape Town and it's windy and wavey here and you don't see people changing their wave board fins, or worrying about any toe in angle.
    Yes, wind and waves are far more important but it is windy and wavy here too for most of the year and it is a shame to let those conditions go past and not experiment as you need those conditions to experiment. And I bet some people do. But in the end, it should not be their job but the people who designed their boards.
    Last edited by Witchcraft; 11th January 2017 at 01:16 PM.
    Bouke
    Witchcraft Windsurfing Fuerteventura

  2. #835
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    Well done for picking through that Bouke, but I feel you are just not going to change his mind.

  3. #836
    Senior Member Witchcraft's Avatar
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    Quote Originally Posted by Jamie.T View Post
    Well done for picking through that Bouke, but I feel you are just not going to change his mind.
    LOL, no for sure not!! Still I get p*ssed off when someone is so ignorant and especially advertising their ignorance as a virtue. As long as others see that, I am happy.
    Bouke
    Witchcraft Windsurfing Fuerteventura

  4. #837
    Senior Member tooold2dance's Avatar
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    Re: balanced,similar looking , harmonic fins forward and back.

    its pretty to look at fins that are similar, but do you really think that different shapes front and back would upset the water flow, bottom shape?

    just running a water hose towards the fins it's visible what happens, this just the surface area, not the fin part that's deep in the water, the flow between them is going to be disturbed irregardless .
    If all K4s were used, the Rocket shape is pretty well different from say the Stubby, and works well enough for me.


    K4 Fins 4Boards TRI-sails Sailrepair




  5. #838
    Senior Member Witchcraft's Avatar
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    Quote Originally Posted by tooold2dance View Post
    Re: balanced,similar looking , harmonic fins forward and back.

    its pretty to look at fins that are similar, but do you really think that different shapes front and back would upset the water flow, bottom shape?
    It is not that, it is how they handle being under pressure, how do they flex and at what point they stall. If one fin is flexy and the other is stiff, the stiff one will have to a proportionally bigger amount of the work and would break out sooner. Also different profiles will have different optimal speeds and AoA´s. If they all work similar/the same, they can handle things better.

    There is also the difference between flex and twist. Twist lets a fin adapt to the flow so the fin can handle more AoA. See Ola´s comments on the cut off fin tip earlier on. You need flex to get twist, which can only be achieved by giving the fin rake/bend but flex alone in an upright fin, not resulting in twist, is of not much use or even worse as it gives less grip. Some 20 years ago I had a single fin board which with a 19cm G10 fin which was not straight, the fin was leaning over to one side, the tip was 4mm out of the centre. This caused the board to have lots more grip on one tack and lots less grip on the other tack.




    .
    Bouke
    Witchcraft Windsurfing Fuerteventura

  6. #839
    Quote Originally Posted by Witchcraft View Post
    I agree with Dkarl that all fins should work together and as such be similar. No one would put a couple of slicks together with off road tires under a car. They may not be as unsimilar as it looks being of different materials but that makes that they could never work any more similar either. A long time ago I found that working with all fins have similar shapes and twist works best so normally when I change something, I change it on all 3. There are also differences due to their individual positions and flow.
    I agree you want the fin cluster as a whole to work together and that it is probably the easiest to have similar shapes and materials because you can take that part of the matching out of the equation. But even when material nor shape is the same, they still _might_ work well together. Here fx, actual flex might be similar between front and rear because the back fins have a flexier design while the front fins have a flexier material. In the board I sail the most, the cut off back fins in fact work very well with the FCS fronts.



    Quote Originally Posted by LDC View Post
    Quote Originally Posted by chrispavlo View Post
    if you would increase finsize of the frontfins, you could tell - there is a reason why most mainstream production trifin/quads using small frontfins..
    There is a reason ...... - your right - but you havn't worked it out yet ...
    Big front fins vs small front fins in quads is simply two completely different styles. For me, it has always been the hardest to get the setups with relatively similar front and back front to work well. This requires the most fine tuning. When one of the sets is more dominating it's easier to set the system up. In particular it is easier with small fronts, because then you almost have a twin set and twin fin boards are overall the most forgiving, and adding small fronts is like adding training wheels.

    Personally I from the start loved Starboards setup with super large fronts, but gradually moved to more equal sized setups to get more all round qualities. But my next quest for my personal riding, I think, will be moving back towards larger fronts again.
    Ola H.

    – Simmer Style Boards and Sails –

  7. #840
    Senior Member Witchcraft's Avatar
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    Quote Originally Posted by Ola H. View Post
    I agree you want the fin cluster as a whole to work together and that it is probably the easiest to have similar shapes and materials because you can take that part of the matching out of the equation. But even when material nor shape is the same, they still _might_ work well together. Here fx, actual flex might be similar between front and rear because the back fins have a flexier design while the front fins have a flexier material. In the board I sail the most, the cut off back fins in fact work very well with the FCS fronts.
    Yes, that is what I said (or meant to say...):

    Quote Originally Posted by Witchcraft View Post
    They may not be as unsimilar as it looks, being of different materials but that makes that they could never work completely similar either.
    Quote Originally Posted by Ola H. View Post
    Big front fins vs small front fins in quads is simply two completely different styles. For me, it has always been the hardest to get the setups with relatively similar front and back front to work well. This requires the most fine tuning. When one of the sets is more dominating it's easier to set the system up. In particular it is easier with small fronts, because then you almost have a twin set and twin fin boards are overall the most forgiving, and adding small fronts is like adding training wheels.

    Personally I from the start loved Starboards setup with super large fronts, but gradually moved to more equal sized setups to get more all round qualities. But my next quest for my personal riding, I think, will be moving back towards larger fronts again.
    Yes, the further away from the centre line, the more flow deflection at the fin base so the more the fin angle and pretwist it should have. Which is hard to figure out. CFD simulation gives a good indication. And the bigger the side fins, the more important this gets to get right. If you have don´t, you are limiting yourself to using small side fins. This can be what suits best for certain boards/styles but perhaps not for others. With testing our new Chakra shape with 10.5 (toe-ed in and pretwisted) and 20.0 trifin set up against a known fast freewave board in a 25cm single fin mode, the Chakra was faster on all points of sail. And having less leverage was easier to control and turn.
    Bouke
    Witchcraft Windsurfing Fuerteventura

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