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 » General Discussion » Weather interpolation

Posted by
Exmeromotu


Users avatar

Posts
71
Registered at
2008-12-10 15:22:17
2010-07-21 06:51:44 - Weather interpolation
Hi!

I've been doing a two boat testing program using different software routers. Obviously the software program whose weather interpolation most closely resembles SOL's weather will do a better job. Since Expedition has a weather animation feature, (once you do a route you can play it back on real time with time steps of 1 minute) it was easy to see that Expedition's weather interpolation scheme is pretty close if not equal to SOL's. Sailplanner also has that weather animation feature, if you move the slider you can see how it all plays out, albeit in 10 minute time steps. But prior experience with Sailplanner is that the weather sometimes has huge differences with SOL's weather specially in light air, and when the wind shifts quickly. Supposedly with the new weather processing upgrades at SOL, Sailplanner's weather will be more "SOL-like" :). But what about Bluewater? As part of my two boat testing program I took a route that was routed using Expedition, and exported that route into Bluewater (waypoints only). Bluewater then recalculated all route data. I was extremely surprised to see that Bluewater's weather interpolation scheme is nearly IDENTICAL to Expedition and SOL. Since Bluewater does not have a weather animation feature (well it does but it's in 3 hour time steps!!) this is harder to visualize. However, you can't argue with the printed output!! Attached is a copy of the file.

Cheers!
Attachments
Posted by
kalle


Users avatar

Posts
413
Registered at
2007-06-01 09:58:04
2010-07-21 09:05:13 - Re: Weather interpolation
Two things affect SP interpolation in comparison to SOL:

1) SP does not interpolate the "wind maps" *at all*, it will only show each "frame" of the weather file. This is intentional so that SP will never show you phenomena that is only artifacts of interpolation. Note however that the SP routing continuously interpolates the weather.

2) If the weather areas in SOL and SP doesn't exactly match, you might be dealing with different resolution of the weather.

--- Last Edited by Kalle Haglunds at 2010-07-21 09:05:50 ---
Posted by
Exmeromotu


Users avatar

Posts
71
Registered at
2008-12-10 15:22:17
2010-07-21 11:57:14 - Re: Weather interpolation
Hi Kalle!

You just confused the heck out of me now... Hehehe! Question, if SP does no weather interpolation and you only have exact grib values on a roughly 2.5 degrees x 2.5 degrees grid, how does SP "fill out" the rest of the space on the map?

I raise this question, because the first time I really noticed a big discrepancy between SOL and SP was during the Inport Quingdao Race ....

Posted by
Exmeromotu
Posts
35
Registered at
2008-12-10 15:22:17
2009-02-09 13:33:24 - Weather Forecasts in Client vs. Sailplanner [ Edit ] [ Quote ]
Hi! During th Qingdao Inport Race I noticed some pretty big differences on the weather forecasts between sailplanner and the game. Aren't they using the same weather provider?


Posted by
Jakob Kuttenkeuler

Posts
355
Registered at
2007-09-04 10:05:30

2009-02-09 14:01:47 - Re: Weather Forecasts in Client vs. Sailplanner [ Quote ]
Yes, they are both NOAA, GFS forecasts. However, in the game we interpolate more than we do in Sailplanner. There is the difference, especially in occasions where large changes (gradients) are present in strength/direction.

...one of the guys behind the game...

That was my question and Jakob's answer more than a year ago...

Cheers

--- Last Edited by Exmeromotu at 2010-07-21 12:00:03 ---
Posted by
kalle


Users avatar

Posts
413
Registered at
2007-06-01 09:58:04
2010-07-21 14:41:31 - Re: Weather interpolation
Sorry I should have been more clear: For the weather maps, SP does not interpolate in *time*, it does interpolate over area.

Please login to post a reply.

Races

Next Race: 00d 00h 00m

Current Races:

The British Isles Circumnavigation 2026


The British Isles Circumnavigation is here! Inviting skippers to take on an epic 1,720nm clockwise voyage around Britain and Ireland! Starting and finishing in Cowes, the course passes some of the most iconic landmarks in offshore sailing, including Fastnet Rock, Tearaght Lighthouse, Black Rock, St. Kilda and Muckle Flugga before the long run home. Racing in our fast and versatile TP52, this Super-Buddy Championship race will reward smart routing, changing weather strategy and sustained concentration over every mile. Good luck!
Race #2052
INFO by brainaid.de
TP-52 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: SUPBUD - SYC
Race starts: Aug 09th 10:00 Registration Open!
▶ Flash
GO TO RACE

SSANZ Triple Series 2026 - Race 2

Welcome back to race two of the SSANZ Triple Series—it's time for the Lewmar 100! Our dynamic fleet of Young 88s returns for another exhilarating 65 nautical mile battle across the stunning waters off Auckland, New Zealand. Once again, our skilled Sailonline racers will test their strategic minds and endurance. With intense competition, shifting conditions, and plenty of tactical decision-making, this race promises high-energy sailing and edge-of-your-seat excitement from start to finish!
Race #2047
INFO by brainaid.de
Young 88 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: SSANZ - SUPBUD - SYC
Race starts: Aug 08th 21:15 Registration Open!
▶ Flash
GO TO RACE

Lake Vättern PYOC 2026


Back in 2013, longstanding SOLer Musigny and his friend xthyra invited us for a three race tour of beautiful Lake Vättern in the heart of southern Sweden. After many years, we return there for a quick sprint from a start in front of the village of Brandstorp, either way around Visingso island in the middle of the lake, but PORT HAND ROUND a buoy off the Granna piers on the eastern shore and back, once again avoiding Visingso as best you can. At least 20nm in trusty Scandinavian 11m One Designs; good luck!
Race #2046
INFO by brainaid.de
11m OD PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: SPQ3 - SPCH - SYC
Race starts: Aug 08th 21:00 Registration Open!
▶ Flash
GO TO RACE

Easter Island to Tristan da Cunha 2026

Welcome to the second leg of our RNW series, rounding Cape Horn. This middle-most leg Round the New World, from Easter Island to Tristan da Cunha, is also part of our Ocean Championship, and as such the second race of OCQ3 2026. This race, like the previous race in the RNW series, will be sailed in our revised 'version 2' Imoca 60 Foil. Race #2050
INFO by brainaid.de
Imoca 60 Foil v2 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: OCQ3 - RNW - OCCH - SYC
Race starts: Aug 03rd 11:00 Registration Open!
▶ Flash
GO TO RACE

Magical Mediterranean 2026 - Benghazi to Korcula

We return to Antiquity’s Middle Sea for a seventh celebration of all things Mediterranean - fickle winds, history and olive oil. This time we will sail from ancient Benghazi, whence once grain shipped continuously to feed Rome’s urban masses, to the medieval Venetian thalassocracy’s port of Korcula, birthplace of Marco Polo; 700nm in classy Club Swan 50s!
Race #1978
INFO by brainaid.de
Club Swan 50 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: MED - SYC
RACE CLOSE: Friday,
August 7 at 2300 UTC.
Race starts: Jul 27th 15:00 Registration Closed

▶ Flash
GO TO RACE

Go to race archive

SYC Ranking

  1. Sailonline Yacht Club Member KaSToR
  2. Sailonline Yacht Club Member WRmirekd
  3. Sailonline Yacht Club Member CriticalHippo
  4. Sailonline Yacht Club Member Panpyc
  5. Sailonline Yacht Club Member rafa
  6. Sailonline Yacht Club Member cdhinman
  7. Sailonline Yacht Club Member rthinman
  8. Sailonline Yacht Club Member ms0689
  9. Sailonline Yacht Club Member BRENTGRAY
  10. Sailonline Yacht Club Member Sax747

View full list

Series

Mobile Client

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

The mobile client