Saturday, August 11, 2012

Career setbacks

I have quoted Beth Winkler's "Jibing is a career" here before, and I'm afraid I'm in the middle of a career setback. For a while, I was able to blame the wind for my poor jibing - it is hard to plane through jibes when you are just barely powered, and there just is not enough wind to get planing after a jibe. But we recently had several sessions with decent wind, where other windsurfers showed that planing through jibes was possible. Here is a list of the GPS data from my best jibes in the last session:
In the best jibe of the day, I slowed down from 24.9 knots at the entry to 6.8 knots at the slowest point of the jibe. That's not really planed through anymore, despite plenty of entry speed! I went back to my database and old GPS files to see what a decent day should look like:
These data are from the same spot (Fogland, RI) with similar winds (18-25 mph southerlies). Despite entering the jibes with less speed, the minimum speeds in the jibes were a lot higher, and I planed through about 4 jibes in this much shorter session. What am I doing wrong?

Well, I did not really have a clew. The GoPro is already packed for moving and in storage, so I have not been able to see myself for I while. I focused on a couple of things I often forget (keeping the front arm straight and pointing the back foot forward), so I was pretty sure that was not the problem. Maybe I had picked up some bad habits by often going for really tight jibes because going upwind in marginal conditions is so hard? Well, a few movies that my friend Dani made from shore last time gave me some pointers:
The board is pointing skyward just as I step and flip the sail. It's not supposed to do that, it's supposed to be flat! If here had been any chop, I would have surely wiped out a second later. Even in flat water, pointing the board like this will kill speed. I'd love to blame the board, but since I have done great jibes on it before, I had to see what I am doing wrong.

The first thing that comes to mind is that I am not putting enough pressure on the mast foot. Well, I have heard that mast foot pressure cures just about anything; it is indeed easy to imagine that somehow pushing down on the mast foot would keep the board flatter. My problem with "mast foot pressure" is that it does not really tell me what to do with my body. Perhaps I could pull downward on the front arm, but that does not really work from me when I am flipping the sail in the middle of the jibe. So let's instead look at what is happening a bit earlier in the jibe:
I'm carving, perhaps a second or two before initiating the sail flip. One obvious problem is that the sail is not sheeted in enough. Here's what it should look like:
In this Power Jibe from the Tricktionary, Rossi has sheeted in at least 20-30 degrees more than I have. Therefore, he does not have any pressure in the sail, but I still do. Rossi's upper body is bent forward towards the nose of the board; I am hanging back a bit, still countering the pull of the sail. Here's a picture of another windsurfer from last weekend who seems to have the same bad habits:
He has already stepped, but you can see from the angle of this body that he is leaning back, bringing the nose of the board far out of the water. Compare this to Andy Brandt just before he starts stepping and flipping the sail:
He has pushed the sailed behind him with an extended front arm. His head is above the mast foot, and the board is nice and flat.

So ok, I should oversheet the sail - I knew that. But maybe I never really understood why. I have heard "to disrupt the laminar flow of air over the sail" - not convincing. I have also heard "to turn the motor off" - but I never knew why I should turn it off. Looking at the pictures above, some possible reasons come to mind:

  • If you keep power in the sail during the turn, you need to counter that power by pulling in the other direction. When you are almost downwind and the sail is wide open, your body weight will be moving towards the back of the board, sinking the tail.
  • But if you oversheet and remove any pressure from the sail, you will have to move your body forward, assuming a neutral, forward-oriented stance on the board. It is also easier to let the rig lean towards the water as in the last picture above, which drives the rail in for more control.
So far, so good - sheet in and carve, let the sail power accelerate you into the turn and pull you up over the board, keep sheeted in and carving so that the sail looses power. With a neutral "surfing" stance on the board, any bounces over chop will not affect your balance.

The next thing to look at is the sail flip and stepping. We'll only consider a step jibe here, where the feet move at the same time as the sail. In the jibe above, I started leaning backwards, so even after stepping with both feet, my weight was still too far back:
Again, the nose of the board is pointing up, the tail is sinking, and my speed is going down rapidly. Because my weight was to far back earlier, it stays back even after the forward step - basically, I am off balance.

One of the things about jibes that has always puzzled me is the pushing of the sail behind you, as Andy does in the picture above (and the video below). I have done it a few times, mostly during ABK camps, and it usually resulted in very nice jibes. But I never really understood why it works. Well, one thing it probably does is that it makes sure that you really oversheet the sail to the point of stalling, and before you are all the way downwind. But I think this is only part of the story. From doing plenty of dry jibes in my kitchen and basement, I think there is a more dynamic aspect to the "push behind": it is a way of winding up for the subsequent sail flip and foot switch. If you do a "Power Jibe" were you open the sail gradually, the step back with the old front foot and the step forward with the old back foot are "static": your overall body position and balance does not change much; if it does, your weight shifts towards the back of the board first, sinking the tail. This will be less noticeable on boards with footstraps that are forward and close to the center like freestyle boards, and more pronounced on slalom or freeride gear.

But if you first push the sail behind you for a second, and then throw your arms and the rig forward, while stepping back with the old front foot, the entire movement becomes much more dynamic. Through the "untwisting", the old back foot will naturally follow the boom end of the sail forward, and the body weight naturally shifts onto the front foot, flattening out the board. With more weight on the front foot, the rig can fall back a bit during the flip without sinking the tail and slowing you down. Then, as you pull the sail forward towards the nose of the board, you naturally move your weight back onto the back foot, and get ready to re-accelerate in bow-and arrow position. Instead of having several separate parts that seem independent from each other, you end up with one fluid, dance-like movement from oversheeting to re-accelerating. Just watch Andy demonstrate:
If you like what you see and you live anywhere close to Cape Cod, make sure to sign up for the ABK Clinic in Hyannis next month! The wind already is picking up, and my bet is that this will be a great fall season on Cape Cod. See you there!

4 comments:

  1. You might want to check the position of the new back foot. It probably needs to farther forward to keep weight forward and off the tail. I normally concentrate on putting the heel of the new back foot into the insole of the other foot before moving it up to the mast. That also helps keeps weight on the heel to continue the carve.

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  2. Thanks, vikingsail! That makes sense. This is much less a problem on freestyle boards, were I can just turn the foot out of the straps, and the back foot remains forward. To the contrary, I sometimes end up with my weight too much forward after stepping.

    But on slalom gear, I have to take a step backward. I usually try to put the old back foot far forward, and then have to put the new back foot one behind it. I'll try leaving the old back foot a bit further back so new back foot can stay in front of it. When I then lift the old back foot, the weight will be more forward.

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  3. Two words: "Back hand"

    It is too far forward, it needs to be further back on the boom.

    Change your feet as early as you can, long before you flip the rig.

    Keep your arms straight, don't bend them and crowd the rig.

    Bend the knees and get low!

    Roo, 27 knot alpha jiber!

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  4. In lighter winds your board speed is much faster than the wind.So when you head down wind and your sail is sheeted out it acts like a break.
    Over sheet look over your mast in the direction you want to go and lean in to the turn.This should put mast base pressure on by it self,it will also keep the board flat.
    I just got my Angulo 85 Magnum and the 8.7 sail from Josh last year. It took my a while to throw he sail at the right time so it wouldn't slow down the jibe. Anything below 10kts and I stall out.

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