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
243
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
297
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
297
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:

Brisbane to Keppel Tropical Yacht Race 2025


When the winter weather turns cool in southern Australia sailors head up to the warmer waters of The Great Barrier Reef and the big winter regattas at Hamilton Island, Airlie Beach and Magnetic Island. But the race isn’t ‘on’ this year; nevertheless, Sailonline is inviting all racers from RQYS and beyond to race the 343 nm for the fun, this time in our SOTO 40. It might be winter downunder but do put on your shorts and t-shirts before you sit down behind your devices to get into the spirit of it all!
Race #1921
INFOby brainaid.de
SOTO 40 Particulars
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: SYC
Race starts: Jun 19th 01:00 Registration Open!
▶ Flash
GO TO RACE

Pantaenius Shetland Race 2025 - Leg 1

Prepare your sails and brace for exhilaration—it's time once again to embark on the thrilling journey from Norway's stunning outer Korsfjorden to the ruggedly beautiful Shetland Isles! Welcome to the first electrifying leg of Sailonline's celebrated two-race Shetland Series. Spanning nearly 190 nautical miles, this year's challenge features the Salona 39, masterfully designed in collaboration with Maurizio Cossutti. Sailonline proudly partners with this iconic race, bringing sailors from around the globe together to test their strategic prowess and seamanship. Whether you're a seasoned veteran or setting out on your first virtual adventure with us, get ready for an unforgettable race filled with intense competition, breathtaking scenery, and the sheer joy of sailing. The North Sea awaits—let the adventure begin!
Race #1922
INFO by brainaid.de
Salona 39 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking:
SHE - SYC
Race starts: Jun 18th 11:00 Registration Open!
▶ Flash
GO TO RACE

Haugesund to Reykjavik 2025


In late April 2016 Draken Harald Hårfagre, the worlds largest viking ship built in modern times, left her home port in Haugesund, Norway and sailed off for a challenging voyage across the North Atlantic Ocean.
The aim was to explore and relive one of the most mythological sea voyages – the first transatlantic crossing, and the Viking discovery of the New World, more than a thousand years ago. History tells us about the Viking explorer, Leif Eriksson, who discovered America over 500 years before Christopher Columbus. The expedition was all about exploring the world, just like the Vikings did.
Sailonline is racing the 1000 nm first leg, from Haugesund, Norway, to Reykjavik, Iceland in our Farr 400. Let us sail in the wake of history on this epic adventure!
Race #1913
INFO from brainaid.de
Farr 400 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking:
ARQ2 - ARCH - SUPSOL – SYC
Race starts: Jun 16th 17:00 Registration Open!
▶ Flash
GO TO RACE

Africa by Sea - Swakopmund to Maputo 2025


Time again to continue our exploration of Africa by Sea, which now takes us around the tip of the continent at Cape Agulhas and up the coast of South Africa to Mozambique’s marvellous Maputo, where we should find good anchorage in the bend of the Rio Espirito Santo (Umbuluzi) once we’ve cleared the 60m high Maputo - Katembe suspension bridge. It’s 1900nm and we’ll be glad to be sailing our comfortable and sturdy Xp-55, as we will certainly experience more headwinds!
Race #1857
INFOby brainaid.de
Xp-55 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: SYC - ABC
Race starts: Jun 11th 17:00 Registration Open!
▶ Flash
GO TO RACE

Marquesas to Young Island 2025

The adventure continues as we launch this fourth leg of the RWW series, racing from Marquesas to Young Island in the Balleny Islands, a group of islands in the Southern Ocean only 62 nm from Antarctica. Get ready for a chilling new challenge as we set sail on the sixth leg of the 2025 Ocean Championship Series! A 4100nm journey of endurance, strategy, and pure sailing excitement. This leg will be pursued aboard the race machine RP66, pushing sailors to their limits. Do you have what it takes to conquer the Southern Ocean? Join us and put your skills to the ultimate test!
PRIZE: SMPF
Race #1909
INFO by brainaid.de
Raichel/Pugh 66 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: OCQ2 - RWW - OCCH - SUPSOL - SYC
RACE CLOSE: Saturday,
June 21 at 2300 UTC.
Race starts: Jun 02nd 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 CriticalHippo
  3. Sailonline Yacht Club Member KaSToR
  4. Sailonline Yacht Club Member FreyjaUSA
  5. Sailonline Yacht Club Member Patrick70119
  6. Sailonline Yacht Club Member Kipper1258
  7. Sailonline Yacht Club Member rafa
  8. Sailonline Yacht Club Member rumskib
  9. Sailonline Yacht Club Member bonknhoot
  10. Sailonline Yacht Club Member Smo

View full list

Series

Mobile Client

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

The mobile client