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mchaco1
Joined: 08 Sep 2010
Posts: 620
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 Posted: Tue Jul 10, 2012 10:51 pm Post subject: |
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Well it was a good conversation and accomplished the main goal of avoiding working 
Im certainly an early windsurfer and dont claim to be much good at it. I am good at physics and arguing though  Unfortunately windsurfing isnt a sport where knowledge of theory counts for a whole lot when it comes to practice. The thing that drew me to windsurfing is that you can know HOW to do something, but take months to actually do it and decades to perfect it. |
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Sailboarder
Joined: 10 Apr 2011
Posts: 168
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| Posted: Wed Jul 11, 2012 5:20 am Post subject: |
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| mchaco1 wrote: | | But right before planing, the longer the waterline the better, if youre in displacement mode then a longer waterline will go faster with less effort and pushing up over that bow wave from displacement to planing will take less effort. |
Well, I disagree too on this one. Technically you are right, but let me explain further. BTW, I am an engineer (a nerdy one I guess), and an intermediate windsurfer. I'm in the phase where I love to think about the physics of windsurfing since I haven't cracked it enough for my taste.
I used to agree. Since I have a longboard and sail in flaky lake conditions, I would use the long waterline to pick up speed. When a gust comes in, I slowly move back on the board and eventually smoothly go up on the plane.
This approach has a few issues. First, I had trouble getting in the straps. When ready for the straps, I would be going full speed allready. I learned how to get in the front stap rather quickly but the backstrap eluded me for a while. I had to read about it and try many things. My position was right, but to lift the foot, or to wiggle it in place at full speed seemed impossible and is still not always easy for me.
The second issue is linked to my Kona One shape. I would get planing in front of the straps, but the board would not release completely. Hard pull without much speed. It was caused by the fact that my board has a banana shape. I was planing on the mid-section of the board. In this setup, the back of the board is raked slightly down, not up. Water release is not good at all. In fact, I heard a few time a strong sucking noise coming from the back. I enventually figured that I need my weight back to make sure that the flat planing area at the back is positionned accurately.
Now, what about pushing over the bow-wave? If the wind is good when starting, I don't even bother with trying to move well in displacement mode. I quickly put my front foot in the strap followed asap by the back one. One good pump and I'm over the bow wave, planing. If the wind is marginal, I will pump once to get planing with front foot only, because the back foot needs to be on the centerline to keep the board level. It is now easy to put the back foot in since I'm planing slowly (but accelerating).
In summary, even if I can get on the plane very passively by using the long waterline of my board, I now prefer to get much faster on the plane by getting actively over the bow wave. A bit more energy involved to get over it, but much less energy spent messing around on the board. |
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mchaco1
Joined: 08 Sep 2010
Posts: 620
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| Posted: Wed Jul 11, 2012 4:29 pm Post subject: |
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| I think its still true if not always the most practical way, my main point was that increasing the waterline is a positive and not a negative thing.There are other dynamics though when the sailor weighs 5-10 times more than the vessel. I think the vectoring of a flat board turns the forces much more towards the vertical and helps lift it up and over , whereas if you try to raise the nose some of the forces will push the board back and take away from the vertical lift. That pump that you give probably also puts a surge of pressure on the mast foot and drives the board flatter as well as forward to overcome that hump. The sinking hard into the harness is similar, flattens the board, drives it forward. For those of us that sail in the gorge, getting on a plane before the straps is like trying to dial a phone while bullriding, but on flat water its fine. |
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