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Sailboarder
Joined: 10 Apr 2011
Posts: 656
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 Posted: Wed Sep 10, 2014 5:36 pm Post subject: |
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| isobars wrote: | | Yes ... but I can't emphasize enough how much of that hassle can be avoided with bigger parts. I'd rather plane easily than futz with a smaller sail. The exceptions include already being on the biggest gear I'm willing to use and being in a temporary lull. |
It was maybe not clear but I fully subscribe to this. I think I had the biggest sail and fin, but was probably one of the heaviest guy too. What I describe was in a sustained lull. Still other were planing around me... |
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Sailboarder
Joined: 10 Apr 2011
Posts: 656
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| Posted: Wed Sep 10, 2014 8:44 pm Post subject: |
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| DanWeiss wrote: | | On the other hand, pushing the front of the board down may actually slam it into the next chop, so we must somehow counteract the fin's power by raising the booms and moving the mast foot forward. Thus balanced, the board will ride more freely and ultimately faster in chop because it now presents itself to the waves in a lower drag position. Power/drag. Simply changing boom/base settings often does the trick to raise the nose and reduce drag enough to not require a more powerful fin. |
Dan,
I knew that riding with a low nose was slowing me down (more wetted area), but didn't think about the adverse effect on getting on plane.
Also, I trust your advice but I'm confused about moving the mast foot forward or backward. If I move it by itself, I know that moving the mast foot forward brings the nose down.
I also think that if I move the boom up alone (and adjust the lines if required), I will have to stand more on the back foot, which raises the nose. I guess since there is less fulcrum advantage for the sail COE, this reduces MFP and also raises the nose.
If I interpret your advice: I bring up the boom, and move forward the mast foot to bring back equal pressure on the feet. The net result should be a higher riding nose. Makes sense? |
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windward1
Joined: 18 Jun 2000
Posts: 1400
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| Posted: Wed Sep 10, 2014 10:26 pm Post subject: |
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Sailborder, I think I see your problem. You wrote: "one of the heaviest guy..."
If you are the heaviest guy out there in a sustained lull, the lightweights will plane right by you. Just about no matter what. All the advice given may help, but being the heaviest in light winds is not to your advantage. |
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jingebritsen
Joined: 21 Aug 2002
Posts: 3371
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| Posted: Thu Sep 11, 2014 5:43 am Post subject: |
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apparent wind is stronger as one pinches upwind toward a peak in onshore conditions. there will be an advantage in planing when going from the downwind shoulder toward the peak, typically in the direction of downwind to upwind. the added vectors of forces from increasing apparent wind and gravity/push from the swell combines. to do so the opposite requires much more power from either the wind or the kit. once one opens the angle of attack well off the wind to try to grab the wave, one loses lots of apparent wind.
trick here is to plane in the advantageous side and jibe without losing a plane going to the opposite way. use the down slope of the swell to assist in those turns.
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DanWeiss
Joined: 24 Jun 2008
Posts: 2296
Location: Connecticut, USA
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| Posted: Thu Sep 11, 2014 9:35 am Post subject: |
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| Sailboarder wrote: | | DanWeiss wrote: | | On the other hand, pushing the front of the board down may actually slam it into the next chop, so we must somehow counteract the fin's power by raising the booms and moving the mast foot forward. Thus balanced, the board will ride more freely and ultimately faster in chop because it now presents itself to the waves in a lower drag position. Power/drag. Simply changing boom/base settings often does the trick to raise the nose and reduce drag enough to not require a more powerful fin. |
Dan,
I knew that riding with a low nose was slowing me down (more wetted area), but didn't think about the adverse effect on getting on plane.
Also, I trust your advice but I'm confused about moving the mast foot forward or backward. If I move it by itself, I know that moving the mast foot forward brings the nose down.
I also think that if I move the boom up alone (and adjust the lines if required), I will have to stand more on the back foot, which raises the nose. I guess since there is less fulcrum advantage for the sail COE, this reduces MFP and also raises the nose.
If I interpret your advice: I bring up the boom, and move forward the mast foot to bring back equal pressure on the feet. The net result should be a higher riding nose. Makes sense? |
Summary of Facts:
Moving mast foot forward only will bring nose down, tail up. Moving mast foot back only brings nose up, tail down.
A more powerful fin only brings tail up, nose down. A less powerful fin brings tail down, nose up.
A higher boom will put more pressure on the back foot.
Analysis:
Combining a more powerful fin with a forward mast foot would logically seem to bring the nose down twice as much, right? However, raising the boom along with the other two (sometimes just one) results in the board's nose floating higher and the board sail flatter more of the time. I can't explain the physics of the larger "triangle" precisely, but it's been a solid concept since windsurfers began to plane.
For example, I raced a AHD's second FW designed for Antoine Albeau, a guy much taller and heavier than me. The board was dog slow upwind and loaded the rig more than I could bear. Exhausting. I moved the mast foot far forward and raise my booms to overhead, to mimic Albeau's geometry. The board suddenly un-wetted, went blazing upwind and, to your concern, became a dream to sail in chop when underpowered. The lower drag on the board allowed me to tune the rig with increased downhaul, reducing rotational lift aka back-hand pull and created a much lighter feel.
A higher boom tends to load the back foot. This in turn should compliment the fin's torque if the fin generates enough, and this is the key! The fin will power-up with increased board speed and/or with proper resistance from your back foot. Floating the nose and raising the tail allows the board to plane higher on the water and more flat, all the while making it easier for you to adjust its pitch while sailing by bending both legs to absorb chop without a significant loss of power.
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Sailboarder
Joined: 10 Apr 2011
Posts: 656
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| Posted: Thu Sep 11, 2014 6:28 pm Post subject: |
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| jingebritsen wrote: | apparent wind is stronger as one pinches upwind toward a peak in onshore conditions. there will be an advantage in planing when going from the downwind shoulder toward the peak, typically in the direction of downwind to upwind. the added vectors of forces from increasing apparent wind and gravity/push from the swell combines. to do so the opposite requires much more power from either the wind or the kit. once one opens the angle of attack well off the wind to try to grab the wave, one loses lots of apparent wind.
trick here is to plane in the advantageous side and jibe without losing a plane going to the opposite way. use the down slope of the swell to assist in those turns. |
This seems consistent with what I experienced. The trick solution is out of my reach for now....  |
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Sailboarder
Joined: 10 Apr 2011
Posts: 656
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| Posted: Thu Sep 11, 2014 6:42 pm Post subject: |
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Thanks Dan, it's very clear and confirms I now understand enough of what's going on.
About loading the back foot, I don't think it's an objective in itself. If the best trim is with the back foot loaded, one could increase comfort by moving back the straps with similar results. This will move some pressure to the forward foot without changing the center of mass of the rider. It works well for my freeride use, but I wonder if it's also true for performance riding. |
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jingebritsen
Joined: 21 Aug 2002
Posts: 3371
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| Posted: Fri Sep 12, 2014 5:01 am Post subject: |
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in order to jibe better, jibe more. seen lots of folks go very long distances on every tack to avoid jibing more. actions speak louder than words. i hear these folks say the words that they wish to jibe better. yet, they keep doing the same thing.
btw, you have noticed that you are planing earlier in one direction better than the other. so that means you are thinking while sailing. keep thinking ways to get better. if you want it enough, you'll figure out how.
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Sailboarder
Joined: 10 Apr 2011
Posts: 656
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| Posted: Fri Sep 12, 2014 8:20 am Post subject: |
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That's true, I need to jibe more often. I like doing long stretches, but it's because I enjoy the speed, knitting through chop and all...
Don't worry, I think too much in general!
Yesterday, there was a similar situation, but not as pronouced and reversed. It was choppy, not "swelly". On one side I was going quickly in both straps, on the other I would often had to mess only in the front strap. It was also my first outing with a 5.2 sail, sometimes well overpowered!
A more free board was helping to go over the chop, and gain speed. I also realized I don't sail often in broad reaches. This would help in getting going on the problematic side, and would be good for my jibes. |
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techno900
Joined: 28 Mar 2001
Posts: 4162
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| Posted: Fri Sep 12, 2014 8:42 am Post subject: |
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There is a point where EVERY windsurfer runs into the same situation - a lull in the wind, but there are still some remaining swells to navigate. You can tune your rig for hours and never see a change if there isn't enough wind to move you and your rig forward with enough power to overcome the swells and get planing.
If the wind is steady and it just isn't strong enough to get you moving, AND you don't have, or want to rig bigger, then some tuning may get you over the hump if there is no other option.
A big guy just needs bigger sails and boards and more wind. While tuning tips are valuable, they are not a replacement for the right size rig.
We have all been there = continue pumping your brains out; head in and rig bigger; try some tuning; slog for a while hoping the wind will build; have a beer on the beach or go home. |
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