Facebook

Login

Support Sailonline

If you haven't already - join the SAILONLINE YACHT CLUB!

Please also consider making a donation - all amounts are greatly appreciated!

Board » Technical Support » qtVlm thread

Page: First Previous 23 24 25 26 27 28 29 Next Last

Posted by
Kipper1258


Users avatar

Posts
251
Registered at
2015-06-18 22:08:49
2018-12-21 22:54:55 - Re: qtVlm thread
Looks like it's working. The link was missing the .exe which I've updated below.

Thanks

https://www.virtual-winds.org/maitai/qtvlm_setup_5.8.6-beta4.exe

Posted by
JB


Users avatar

Posts
305
Registered at
2013-03-07 08:54:34
2018-12-25 11:49:39 - Re: qtVlm thread
In past years we saw a quick evolution not only on weather routing software but also on sidekicks aiding tools.
One of the best weather routing programs used around the corner is qTVlm. Since the very first versions it has been upgraded in a good rhythm bringing also a plethora of innovations, sometimes using info and suggestions gathered from the community.

Anyhow, one qT aspect that has been roller coasting is the Optimizing/Simplifying algorithm processes applied to the calculated routing WPTs.

It is very simple to verify that in spite of using the “Optimum Simplify” process first, and "Optimize" after (applied only once or several times), normally we won’t get the best ETA - even before any trimming operation on the fixed calculated WPTs, the ones in “red” color generated around land/rocks/barriers and on the remaining "green" movable ones.

The cause for this is identified. Is a direct consequence of the used decimating algorithm implemented in qT for the “Simplify”/ “Optimum” processes.

In recent versions - 2018 - this issue was aggravated as the decimating operation during the “Simplify” process stopped being uniformly applied along the routed path, leaving us to the somehow paradox of having more remaining WPTs in the end of the route, precisely where the predictability of the WFs are worse, which is a contra sense.

There are ways to overcome this issue but, again with another contra sense, as you have to spend more time rehabilitating an over decimated routed path by adding new WPTs.

Every WPT over decimated is a less one degree of freedom in the generated curve, giving here the main reason for qT going in opposite direction of the optimum ETA.

Sincerely hope that qT responsible persons take once for all this issue and, at least bring back the “old” decimating algorithm, the uniform “cutter”.

João/psail
Sail Fair.
Posted by
maitai


Users avatar

Posts
114
Registered at
2016-02-25 08:15:33
2018-12-25 14:16:00 - Re: qtVlm thread
Joao, you should also mention that you are using settings that I strongly say you should NOT use...

Running a routing with 5mn isochrons can only lead to disappointment in most cases. If I allow for 1sec isos would you use it? 1ms even better? Even less?

Using such a small amount of time between isos creates way too many points that are likely to look useless to the simp process, which can only do what it is aimed to do: simplifying (i.e. remove the point if the ETA is not worst). Since there is not enough room between points it will end up by over simplifying.

Conclusion is that there is a good reason behind the default values, what else can I say? Modify them at your own risk, but do not complain if you don't like the result.

I could add a few things:
1) Routing with 5mn interval on a 3 days travel is just ridiculous knowing that the real wind is different from the grib's wind and that anyhow next grib update will just completely rebate the cards.
2) qtVlm is not specifically designed for SOL and will never be. qtVlm is designed for real sailors or racers and does not try to give an exact answer to an infinite problem. It is just a toolbox that can help to decide where to go.
3) qtVlm is also used in official scientific projects and is also used by very famous racing teams over the world. No one is using 5mn isochrons, there must be a reason.
4) We are opened to suggestions and improvements and even complains. But it need to be reasonably compatible with the real world, and concerning bugs it needs to be reproducible with reasonable settings.

Happy Xmas to all
Philippe.

--- Last Edited by maitai at 2018-12-25 14:16:38 ---

--- Last Edited by maitai at 2018-12-25 14:17:03 ---
Posted by
JB


Users avatar

Posts
305
Registered at
2013-03-07 08:54:34
2018-12-25 17:14:22 - Re: qtVlm thread
Hi Philippe and all.
Good afternoon.

Well, the settings I’ve been using a long time (since they were available) are the same, so I don’t have any induced distortion on comparing results generated with different settings.

Those settings have proved to give results in all kind of WFs and with different boat Polars, being also more relevant with the faster boats, as you easily understand and as per example I sent you recently.

Correct, the lower the Time Step (TS) used for calculating the Isochrones, the bigger will be number of potential WPTs. That’s the price for getting precision.

The first point you mention misses rationality.
We all know that ANY GRIB file won’t be exactly what you are going to sail IRL. Under that argument - yours - I ask why do we make routings?

I totally agree with your second point and part of the third. For that I can give you one plausible answer for people not using TS = 5 minutes: I takes a lot of time to get a result, not because is less precise.

In relation to fourth point, previously I gave you a suggestion: bring back the old "cutter", which I now reiterate.

If it doesn’t have anything to do with the used TS, what’s the problem for implementing it again?

My Dear Friend have also
a Merry Xmas

João/psail
Sail Fair.
Posted by
Bimmer


Users avatar

Posts
447
Registered at
2015-02-23 15:38:27
2019-04-29 14:00:01 - Re: qtVlm thread
Hi there maitai and oxygen 77. I'm writing to you as the original "matchmaker" between QtVlm and sailonline.
I am sorry to tell you that Joâo/psail have suffered from a heartattack and has deceased.
He's very missed in SOL as you can read in other forum posts, and I'm also sure he'll be missed as a very determined "hawkeye" to whatever the small issues could be in our use of your absolutely amazing program.
It's my hope that someone else in the SOL community will be as sharp as he was.
But again - SOL, as a whole, is MORE than satisfied with using QtVlm.
Thank you again :-)

--- Last Edited by Bimmer at 2019-04-29 14:01:00 ---

--- Last Edited by Bimmer at 2019-04-29 14:01:51 ---
Posted by
maitai


Users avatar

Posts
114
Registered at
2016-02-25 08:15:33
2019-04-29 17:49:00 - Re: qtVlm thread
Very sad news. We had a lot of exchanges to improve qtVlm usage with sailonline.

All my thoughts to his friends and family.
Posted by
sol


Users avatar

Posts
299
Registered at
2008-08-14 11:08:14
2019-05-05 17:11:55 - converting qtvlm-route to brainaid dc-tool
skippers,
Concerns QtVlm version 5.8-9
If you export a QtVlm-route to csv to generate values for brainaids dc-tool you will see that QtVlm has inserted some new columns.
COG is found now some columns to the right.

If you use your 'old' convertor now you get knots in stead of degrees you expect.

greetings
LacSareno


--- Last Edited by sol at 2019-05-05 17:14:41 ---
Posted by
Bimmer


Users avatar

Posts
447
Registered at
2015-02-23 15:38:27
2019-05-06 11:42:41 - Re: qtVlm thread
Solution:
Change SOG to COG(T).
See screen shots.
Also works for AGL.

--- Last Edited by Bimmer at 2019-05-06 11:46:50 ---
Attachments
Posted by
sol


Users avatar

Posts
299
Registered at
2008-08-14 11:08:14
2019-05-06 13:52:35 - Re: qtVlm thread
@Bimmer,
Are you sure you want to use AWS for sign of TWA? I think TWA now will get always the same sign.

LacSareno


--- Last Edited by sol at 2019-05-07 14:01:14 ---
Posted by
Bimmer


Users avatar

Posts
447
Registered at
2015-02-23 15:38:27
2019-05-07 10:47:31 - Re: qtVlm thread
I'll look into that, thanks LacSareno :-)

Page: First Previous 23 24 25 26 27 28 29 Next Last

Please login to post a reply.

Races

Next Race: 00d 00h 00m

Current Races:

Tall Ships 2026 - Harlingen to Antwerpen


Welcome to the second of four virtual Tall Ships Races in European waters which are concurrently being organized in-real-life by Sail Training International . This second race is from Harlingen in Friesland down along the coast of Holland and Friesland to Vlaanderen’s famous port of Antwerpen – circa 150nm in Sailonline’s classic Clipper 240.
NOTE: Starts and Finishes in tall ships racing are always offshore to avoid conflict with shipping and shipping lanes; online and real-life may not match exactly.
Race #1993
INFO by brainaid.de
Clipper 240 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: TSI - SUPBUD - SYC
Race starts: Jul 06th 16:00 Registration Open!
▶ Flash
GO TO RACE

Alaska to Easter Island 2026

Welcome to yet another all-new series. The initial leg of the RNW (Round the New World), Alaska to Easter Island, also part of our Ocean Championship. The first race of OCQ3 2026. This race will be sailed in our revised 'version 2' Imoca 60 Foil. Race #2042
INFO by brainaid.de
Imoca 60 Foil v2 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: OCQ3 - RNW - OCCH - SYC
Race starts: Jul 06th 11:00 Registration Open!
▶ Flash
GO TO RACE

Cross the Convergence 2026 - Sao Tomé to Tristan

The fifth race of our series of ocean voyages across the World’s convergence zones takes us back south down the Atlantic from Sao Tomé on the Equator to Tristan da Cunha on the edge of the Roaring Forties. It’s 2500nm; in your path the Benguela winds and current along the south west African coast, and behind that the St Helena High stretching halfway to South America. So, mind where you go in your Volvo OD65 version 3 (based on sampled real-life race data by kroppyer)!
Race #1985
INFOby brainaid.de
Volvo OD65v3 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: CCZ - SYC
Race starts: Jul 03rd 18:00 Registration Open!
▶ Flash
GO TO RACE

New Ice Age 2026 - Neumayer Station to Scott Base


For a second-half of long-distance ice-boating, we take our DNs to Antarctica for a circumnavigation of that continent in two legs clockwise, in harmony with the prevailing winds (such as there are), beginning with a race from Germany’s Neumayer Station to New Zealand’s Scott Base. It’s about 3500nm, which, if there’s wind at all, should, well-wrapped in your DN-cockpits, not take you much more than five days. And remember: charts down here are unreliable – what is land and what is ice?!
Race #1970
INFOby brainaid.de
DN PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: NIA - SYC
Race starts: Jul 02nd 07:00 Registration Open!
▶ Flash
GO TO RACE

Tall Ships 2026 - Aarhus to Harlingen


Welcome to the first of four virtual Tall Ships Races in European waters which are concurrently being organized in-real-life by Sail Training International . The course for this first race is from Aarhus in Denmark, through the Skaggerak and down the North Sea to Friesland’s Harlingen – a proper tall ship training adventure of circa 450nm, which online this year you will race in Sailonline’s classic Clipper 240.
NOTE: Starts and Finishes in tall ships racing are always offshore to avoid conflict with shipping and shipping lanes; online and real-life may not match exactly.
Race #1992
INFO by brainaid.de
Clipper 240 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: TSI - SUPBUD - SYC
Race starts: Jun 27th 16:00 Registration Closed
▶ Flash
GO TO RACE

Viareggio Bastia Viareggio 2026

Our sixth race of nine to celebrate all things Mediterranean - fickle winds, history and olive oil - was planned to be our third buddy-up with another incredible Italian event, the Viareggio Bastia Viareggio (or BVR for short). Unfortunately, in-real-life the BVR has been cancelled this year. But online we shall race it never the less. It’s a quickie – a 160nm roundtrip there-and-back in classic Class 40. Have fun, and if you’re planning a BBQ, piccola isola Capraia halfway across is simply lovely!
Race #2041
INFO by brainaid.de
Class 40 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: MED - SUPBUD - SYC
RACE CLOSE: Sunday,
July 5 at 2300 UTC.
Race starts: Jun 24th 12:00 Registration Closed

▶ Flash
GO TO RACE

Bluefin Tuna - Mexico Gulf to North Sea 2026

Join us and follow the Bluefin Tuna, as they migrate from their spawning grounds in the Gulf of Mexico to their feeding grounds in the North Sea off the coast of Norway. This 4300 nm race is part of our Ocean Championship and the final race of OCQ2 2026, and also the second leg of our Migration series. We will be sailing in our Gunboat 90. Race #2035
INFO by brainaid.de
Gunboat 90 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: OCQ2 - MIG - OCCH - SYC
RACE CLOSE: Saturday,
July 4 at 2300 UTC.
Race starts: Jun 08th 11:00 Registration Closed
▶ Flash
GO TO RACE

Go to race archive

SYC Ranking

  1. Sailonline Yacht Club Member WRmirekd
  2. Sailonline Yacht Club Member KaSToR
  3. Sailonline Yacht Club Member CriticalHippo
  4. Sailonline Yacht Club Member bonknhoot
  5. Sailonline Yacht Club Member Panpyc
  6. Sailonline Yacht Club Member cdhinman
  7. Sailonline Yacht Club Member rafa
  8. Sailonline Yacht Club Member HoratioPugwash
  9. Sailonline Yacht Club Member YANN
  10. Sailonline Yacht Club Member ms0689

View full list

Series

Mobile Client

SYC members have the benefit of access to our mobile/lightweight web client!

The mobile client