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Vmg

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adrenalineendorphin
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Re: Vmg

Postby adrenalineendorphin » Mon Apr 19, 2021 8:25 pm

knot_moving wrote:
Mon Apr 19, 2021 4:37 pm
If you pick a good sea breeze day then you will see 10-20 deg shifts about ever 2-4 minutes. You should be able to see these very clearly when riding upwind.
- they should also be very clear in your data.

.
.
.

... you prob know all this - guess I will change my username to CaptObvious284
Thanks a lot. I know the physics, I know the math, I have some experience, I would just like to see PRO's tracks as I'm stuck on the local lake in Pandemia.

evan
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Re: Vmg

Postby evan » Tue Apr 20, 2021 12:11 pm

adrenalineendorphin wrote:
Mon Apr 19, 2021 11:46 am
How do you know this? What is your source? Can you share some .gpx files of current racers?
Some old graph of me from two years ago with PLKB prototypes and Moses comet race foil, 15kn vmg up and 25kn vmg downwind. Current Flysurfer VMG2 + Levitaz R5 + extra training are quite a bit faster but broke my velocitec gps and didn't need/found a good replacement yet so no recent data. (gps watches have too much noise in the data for graphs)

Training partners are currently doing 22-25kn up and 30-35kn downwind speed, don't have the exact angles for the vmg calculation but they are roughly the same (if not better) than two years ago so both speed and vmg have gone up quite a bit.
Attachments
2019-05-13 aero p12 vmg.png

adrenalineendorphin
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Re: Vmg

Postby adrenalineendorphin » Wed Apr 21, 2021 1:01 pm

evan wrote:
Tue Apr 20, 2021 12:11 pm
Some old graph of me from two years ago with PLKB prototypes and Moses comet race foil, 15kn vmg up and 25kn vmg downwind. Current Flysurfer VMG2 + Levitaz R5 + extra training are quite a bit faster but broke my velocitec gps and didn't need/found a good replacement yet so no recent data. (gps watches have too much noise in the data for graphs)

Training partners are currently doing 22-25kn up and 30-35kn downwind speed, don't have the exact angles for the vmg calculation but they are roughly the same (if not better) than two years ago so both speed and vmg have gone up quite a bit.
Thank you so much for the data! Really helping me. :)

I have experience with Flysurfer Sonic 3 (15m and 11m). I use them on 17m lines.
On upwind: If I go with 18-19 knots SOG I get about 13 VMG. If I go faster (20-22 knots) I lose some VMG (I go down to 9-12 knots)
I just received a Flysuerfer VMG 21 and I haven't tested it yet. Do you think it will help me reach better VMG? Or the Sonic 3 is good enough and my technique is not good enough to reach the ~15 knots VMG?

One thing I noticed: where I train on Lake Balaton it is always much more choppy than I see racers ride and it makes it difficult to edge hard because the hull can hit the waves often, so sometimes I need to satisfy angle to be able to fly over the waves.

evan
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Re: Vmg

Postby evan » Wed Apr 21, 2021 7:35 pm

adrenalineendorphin wrote:
Wed Apr 21, 2021 1:01 pm
What foil+board are you using? That will possibly make a bigger impact than switching to a vmg(2).
Wind chop shouldn't impact the speeds that much unless it is really short and more than 1m. But still it will impact the Downwind more than up.
Try getting up to speed first consistently and improve the angle as a second step. You should be able to ride 30kn on a 70-90deg course.

adrenalineendorphin
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Re: Vmg

Postby adrenalineendorphin » Mon Apr 26, 2021 3:49 pm

evan wrote:
Wed Apr 21, 2021 7:35 pm
adrenalineendorphin wrote:
Wed Apr 21, 2021 1:01 pm
What foil+board are you using? That will possibly make a bigger impact than switching to a vmg(2).
Wind chop shouldn't impact the speeds that much unless it is really short and more than 1m. But still it will impact the Downwind more than up.
Try getting up to speed first consistently and improve the angle as a second step. You should be able to ride 30kn on a 70-90deg course.
I use Moses Comet 111 mast with Moses Havoc wings.
I use a custom board 4.2 kg

I can ride upwind 22-23 knots (SOG) with a VMG of 8-10 knots. That is comfortable and I think the speed is okay (based on previous comments) so I should improve the angle to get a better VMG.
On downwind my max speed is 31 knots, but I always get over 25 knots and often above 27-28 knots. (when it is choppy I don't go this fast)

Wave chops are rarely 1m, but almost 1m high. And they come in a very short period.

trashboat
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Re: Vmg

Postby trashboat » Thu Apr 29, 2021 6:01 am

The SAP Sailing website has tracks and a ton of data for all types of sailing. The most recent Formula Kite regatta they seem to have tracked was in 2019, but I think still valuable: https://www.sapsailing.com/gwt/Home.htm ... ula%20Kite

Unfortunately I haven't figured out how to export data for better analysis, but the Competitor Chart tab can show you VMG and SOG, among other things. Very detailed.

evan
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Re: Vmg

Postby evan » Sat May 08, 2021 10:00 pm

adrenalineendorphin wrote:
Mon Apr 26, 2021 3:49 pm
I use Moses Comet 111 mast with Moses Havoc wings.
I use a custom board 4.2 kg

I can ride upwind 22-23 knots (SOG) with a VMG of 8-10 knots. That is comfortable and I think the speed is okay (based on previous comments) so I should improve the angle to get a better VMG.
On downwind my max speed is 31 knots, but I always get over 25 knots and often above 27-28 knots. (when it is choppy I don't go this fast)

Wave chops are rarely 1m, but almost 1m high. And they come in a very short period.
Here some data of today, 15m vmg + R5 with 18-23kn I guess on pretty flat water for those strong winds.

Practice on staying locked and powered while letting the kite breathe, the gear should be able to come a lot closer to my numbers but it is hard to train alone without a better rider to follow.
Attachments
vmg down 2021 05 08.jpg
vmg up 2021 05 08.jpg
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toyletbowl
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Re: Vmg

Postby toyletbowl » Sun May 09, 2021 12:02 am

Have a related question. Hope you guys don't mind.

I do a fair amount of snowkite racing and always wonder how to determine the lay line? I just look over my shoulder for the mark and go with it.
Is there any other way to do this that is more accurate? Seems Like watching the foil racers on the water that they never miss the lay lines.

Thanks in advance for any suggestions.

Bob
www.kiteridersllc.com

evan
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Re: Vmg

Postby evan » Sun May 09, 2021 5:32 am

Watch closer, they do miss more often then you think ;)

You need to get a feeling for what angles you can make for the optimal vmg in the given wind conditions and predict wind shifts. Normally they overshoot the layline a tiny bit and burn it off with extra speed to get close to optimal vmg but it is also key to make the layline not too long as the further away from mark you are the bigger the mistake is you can make. This is one of the key things that differentiate the good racers from the best.

toyletbowl
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Re: Vmg

Postby toyletbowl » Mon May 10, 2021 12:17 am

Thanks Evan,

Perfect. The comment of being closer to the mark makes a lot of sense to reduce the chances of a larger miss.

Bob
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