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  1. #1
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    A microwave study

    I guess it's hard to escape a piece of advice or three if you're the son of the most winning windsurfer ever. So let's just assume that junior did something right when he frontsided the smallest imaginable wavelet in very onshore conditions at "Sideshore" (Playa Įguila) today. As the whole top-bottom-top combination probably happened within a circle with a diameter of less than fifteen meters and the distance from my camera was easily seven times that, it seems fair to assume that any difference in sheeting angle as it appears in the pictures (will hopefully be posted with friendly help) is mostly due to actual changes in the angle of sail relative to wind rather than just relative to my lense.

    Relative to the wind, juniors sail stays sheeted to almost the same angle all through most of the ride. To make this happen he does of course have to twist his body and make best use of elbows and shoulder joints but exactly how is not my focus here. My focus is on how the sail is sheeted to the wind. And it's almost unchanged through the ride as the board turns around more than 180 degree.

    There are two exceptions:

    The first is the little sheeting in he does to turn off the wind down the wave.

    The second is more pronounced and happens as he turns back up the wave for the front side top turn. Rather than open up the clew or twist his body to the maximum to avoid back winding, he allows the clew to swing further into the wind. By comparing his sheeting angle to the outgoing sailor in the background, you can see that it's very similar. My guess is that at this point he actually reverses the sail power and gets a little drive clew first up the wavelet before he (as expected) pushes the clew open again for the top turn.

    As I see it this microwave study on a slow onshore wave where the difference between apparent and true wind speed and direction is modest, illustrates how sail power is reversed for a split moment in the "vertical part of the ride". And that this isn't achieved by twisting and shouting to the max. It's rather the opposite!

    The moral is I believe that being overly concerned with the risk of back winding is unproductive. People who keep opening the clew all the way through the turn will effectively choke the sail and stall. Note too that with a faster wave the risk of backwinding is even smaller.

    I think that many windsurfers are like scolded cats. Just like walks of shames can produce permanent far outers and catapults produce hang backers, backwinding on frontside attempts produces sail chokers that stall before the top turn. Been there done that.
    Last edited by boards_Tomas; 5th February 2017 at 08:55 AM.
    The infamous wavewriter

  2. #2
    Senior Member Mark D's Avatar
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    Click image for larger version. 

Name:	junior wave.jpg 
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ID:	14833
    Photos from text above.
    Had to put them together then reduce it as a jpeg to small size.
    (Hence Low quality)
    Used Mac 'Preview' program to open PNG of image.
    Chose select on Macbook and exported as a Jpeg
    Moved the slider till it was around 1MB in size. (Original was 3.8MB)
    I can see why folk just post stuff on Facebook now as it is a faff reducing size to such low quality.

    I suppose other options would be to link to an album or photos uploaded to an external site e.g. Flikkr, a blog type site or a specific Facebook page (open to Public...so not without issues)

    Edit: I think image 2 and 3 are the same! It was difficult to see on the iPad.

    M
    Last edited by Mark D; 5th February 2017 at 10:27 AM.
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  3. #3
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    Thanks Mark, next time I will publish on an open FB forum and just link. I'll get over the shame of writing in foreign language on a Norwegian forum.

    There was actually a longer sequence of pictures that illustrated how the sail is mostly sheeted to an almost identical angle. Which allows for the interpretation that the sailor actually holds the sail still while "simply" turning the board around under it.

    But then as shown in picture 4 above he suddenly lets the clew point much further into the wind (effectively copying the sheeting angle of the outgoing sailor but clew first) before the top turn when he proceeds to push it way out again to exit as in picture 6.

    But enough wave writing for now, I'm going waveriding!
    Last edited by boards_Tomas; 5th February 2017 at 10:59 AM.
    The infamous wavewriter

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