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 27 28 29 30 31 32 33 Next

Hi Satori. I liked your Rum Run report. Figuring out how to squeeze a little bit more out of QtVlm routing is part of the fun for some of us. I think you are on the right track with your experiments. I am still learning too, but some of the things I try are:
1) Using barriers is a good way to force the routing to go around a buoy, or to close off possible paths that lead nowhere (like dead end fjords) and thus made the routing faster.
2) Another way to optimize/simplify faster is by using the "Selection" tool (blue square icon) and only optimize/simplify on that selected part. Much faster, especially on multi-day routings.
3) Watching the isochrones unfold during a routing is important to spot tactical alternatives. I mark them with waypoints and then do separate routings from boat to those waypoints to see how much they differ in time and to see which routes are improving (or getting worse) on subsequent WX updates.
4) As you pointed out in your report, with tallship polars QtVlm can sometimes struggle with the polar hops. You can then see the isochrones behave strangely and may even fall apart completely. Then you have a very unreliable routing. In that case try to route again with longer steps.
5) Varying the step can also give you routes that optimize better. 30 minutes or even 1 hour steps will sometimes give you quicker routes that a routing with 5 minute steps didn't find. Experiment.
6) It's also important to verify. Your boat position after 4 or 5 hours should be very close to where your used routing indicates it should be. If not you may be on wrong polar or be using an out of date grib. Both have happened many times to me. Checking where my boat is helps me to spot those problems.
7) When the routing tackes/gybes a lot it is often useful to adjust the route manually, before simply/optimize. Reduce the number of tacks/gybes can give you a faster ETA.

Good luck.
Interesting. I wasn't aware of the 'selection tool'. I'll have to give it a go.
@Satori Another great race report for the recent Hatteras Sprint. I have had a busy week, so here are my belated comments to some of the points you raise about Qt routing.

It's important to experiment with some settings and find what works for you. This may vary depending on the boat polar and on the type of race.
I always set my crank duration to 1 minute for max accuracy. Simplify/optimize the route will reduce the number of DCs anyway.

In the boat settings for "tacks and gybes" is where many SOLers probably use very different values. This is the part where Qt is the least accurate because the PL loss formula in SOL differs from what Qt does. I prefer to set both tacks and gybes to 97% of polar speed for only 1 crank. In reality, depending on the wind speeds, my PL penalty will be more than that. But I will take that into account when I clean up my route. With those settings I know it will tack and gybe more often than needed. I manually improve my route when it has lots of tacks, as was the case in first part of the race here.
I just tacked manually going on max VMG, and I didn't use the intermediate tack to try to limit PL. In this case the boat speed was mostly around 7 kts. My PL always recovered to 100% within 1 or 2 server updates. Then I don't believe you can gain much by going on a lower speed for 10-20 seconds. That's like giving yourself a 30% performance penalty for 1 or 2 server updates. That doesn't pay off.
At boat speeds of >12kts it becomes another matter.

Where the router was very helpful (and will usually beat sotp navigation) is in the curved passages we had just before and after Hatteras inlet. I believe that's where I gained some time on most of the other boats. This are the type of passages where you can let the wind steer your boat without getting any PL. That's what I did here. I kept switching between COG and TWA to turn my boat to the wanted COG directions.
At Cape Hatteras turn it was of course straightforward, no router needed. Being only 0.01 NM behind I knew there was a chance to win by taking a bit more risk.
What I do there is set a DC that will turn about 10-12 seconds after the Cape. But at the same time I am ready to turn my boat a little bit earlier with a direct command. In this case I probably pushed the command about 8 seconds before the DC would have fired, when I eyeballed my boat to be right at the corner. That put me on inside with a slightly better angle.

It is really small differences that decide this kind of races. You have to squeeze out every inch you can, because many others are doing the same.

For short races like this one I route with 5 minute step. In longer ocean races I usually do 15 or even 30 minute steps. But it is important to test and compare with other step sizes. In some case you get better results with longer steps. Testing = knowing.




@Satori On the topic of NMEA failing to connect. I have had it a few times, but not nearly as often as you report.
Up to know I have always fixed it by closing both AGL and qtVLM. Then first restart AGL and wait until it has properly connected. You can see when it has connected to server. Can take as much as 30 seconds.

Then I restart qtVLM and it always connects to NMEA very quickly.

One thing you may want to check. Click on the boat in top-right in qtVLM to open a bunch of tabs. There is a tab for NMEA and there you can change the "update interval". Mine is set to 3 seconds. You may test and see if other values solve your problems. May too often can cause a bottleneck. Or too infrequent may cause connection loss. Just try.
Attached is the gist of the email I sent to Satori who has indicated he will tidy it up and post it somewhere when he has the chance. Meanwhile, this might help get a few more SOLers into QtVlm and routing in a fairly simple way with instructions which follow the normal sequence of routing using QtVlm for SOLing.

I'll monitor for queries and suggestions and try to incorporate what I can into the tutorial as time permits.

Attachments
One configuration setting which is useful to adjust is under the advanced tab. There you can adjust the amount of detail shown in coastlines. For more detailed routes near land it could be useful to raise the level of detail.
Dingo - would you be happy for me to include that as a QtVLM Quick Guide under the Links tab?
Hi Dingo or anyone for that matter. Question...How do you copy a Location from qt to enter into aGages Optimum Angles Tool to work out the best VMC?
I have worked it out. The coords must be decimal and without the degrees symbols. Set this up in settings. Otherwise its the same almost. Alt and click then there is a box that opens up. Copy the coords into Agages tool and remove the symbols and off you go!
Hello,

I'm new to SOL and I am trying to connect the game to qtVlm ... with some difficulties :-)

I am using the brainaid proxy server to export NMEA data to qtVlm. The server is properly running and qtVlm receives now a NMEA feed (NMEA raw data window shows it).

The brainaid server receives data from a boat that is sailing in the "Shetland race 2021".

The problem is that nothing happens on the screen. The race WP are not shown, my boat is not positioned and all instrument are inactive.

Once qtVlm receives properly the NMEA feed, is there any other setting that is to be activated so that the feed can be processed concretly? Or maybe the feed itself doesn't contain the proper data?

Has anyone of you already had this kind of problem in the past?

Page: First Previous 27 28 29 30 31 32 33 Next

Please login to post a reply.

Races

Next Race: 00d 00h 00m


Current Races:

Java Sea Race 2022
For our penultimate Seven Seas of Asia race, we invite you to venture yet further south – to the Java Sea for a hydration-challenging circa 2200nm race Jakarta to Semarang via Selayar and Belitung, in cracking kinetic Ker 40s. Water-makers will again be mandatory!
Race #1545
INFOby brainaid.de
Ker 40 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: SYC - SSA
Race starts: Aug 20th 06:00 Registration will open soon

▶ Flash
GO TO RACE

Victoria to Maui 2022
The Victoria to Maui International Yacht Race, first contested in 1968, is the pinnacle of Pacific Northwest ocean racing, running every two years. This year, Sailonline invites the SOL fleet to race the 2300nm course in Delphia 47s, from Victoria, British Columbia to Hawaii, finishing off Lahaina Maui.
PRIZE: SMPF
Race #1596
INFOby brainaid.de
Delphia 47 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking:
OCQ3-OCCH-SUPSOL-SYC
Race starts: Aug 09th 19:00 Registration Open!

▶ Flash
GO TO RACE

Brisbane to Hamilton Island Yacht Race 2022


Time once again to head for the warm waters inside The Great Barrier Reef, but this year not only online but together with our buddies at the Royal Queensland Yacht Squadron and their friends from across the world, in the iconic Brisbane to Hamo! Online we’re racing maxi’s to give you a chance to cover the 550 glorious blue water nautical miles in a time to best some of the fastest monohulls on the planet including Andoo Comanche, Black Jack and Hamilton Island Wild Oats . Fair winds, all!
Race #1606
INFOfrom brainaid.de
Super Maxi 100 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: SYC
RACE CLOSE: Sunday,
August 14 at 2300 UTC.
Race starts: Aug 05th 01:00 Registration Closed
▶ Flash
GO TO RACE

Sailonline’s 15th Birthday Balloon Race
Sailonline offers a huge variety of boats to sail in. One of the more unusual ones has got to be SOL's Balloon, which was polarized by past SOLmaster 76Trombones. Notably, the SOL Balloon will actually ‘sail’ in other directions other than straight downwind, although it will not 'sail' over land or beyond a 'beam reach'. Like in 2013 and 2018, we will be taking the Balloon across the Atlantic from St. John's and 'land' it in the sea off the Cliffs of Moher.
Race #1605
INFO by brainaid.de
SOL Balloon PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking:
None
Race starts: Aug 01st 19:00 Registration Open!

▶ Flash
GO TO RACE

Go to race archive

SYC Ranking

  1. Sailonline Yacht Club Member WRmirekd
  2. Sailonline Yacht Club Member Pit8008
  3. Sailonline Yacht Club Member rafa
  4. Sailonline Yacht Club Member FreyjaUSA
  5. Sailonline Yacht Club Member Vida_Maldita
  6. Sailonline Yacht Club Member GREATSKUA
  7. Sailonline Yacht Club Member Satori
  8. Sailonline Yacht Club Member Sax747
  9. Sailonline Yacht Club Member Kipper1258
  10. Sailonline Yacht Club Member HappyHour

View full list

Series

Mobile Client

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

The mobile client