Sailonline.org - Online Sailing

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!

Tweets by @sailonline

Board » General Discussion » Weather interpolation

Posted by Exmeromotu 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 Interpolation_Excercise.xls (48.5 KB)
Posted by kalle 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 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 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:

Flight of the Godwit - Hegura to Anchorage 2024

Welcome to the second flight of our bar-tailed Godwit!. This race is the second of three legs reflecting the bird's annual migratory route, and simultaneously the fifth leg of the 2024 Ocean Race Championship. The voyage promises to be not only a test of skill and strategy but an immersive experience in the beauty of the archipelagos of the Aleutian Islands. Join us as we push the boundaries of seafaring prowess on this epic adventure. Let's fly like a godwit!
PRIZE: SMPF
Race #1791
INFOby brainaid.de
Maxi Trimaran PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: OCQ2 - GWT - OCCH - SUPSOL - SYC
Race starts: May 06th 11:00 Registration Open!

▶ Flash

GO TO RACE

Bay to Bay 2024 - Leg 2 - Great Sandy Stait

Get ready for another spectacular day on the water with the second and final race of our thrilling series! This time, the challenge extends to an ambitious 21-nautical-mile course through the scenic Great Sandy Strait of Australia. After a joyful post-race BBQ, our daring sailors will once again take the helm of their Seascape 18s! Expect more high-speed action, strategic sailing, and, of course, another fantastic BBQ to celebrate the end of this exciting series!
Race #1802
INFO from brainaid.de
Seascape 18 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: B2B - SYC
RACE CLOSE: Wednesday,
May 8 at 2300 UTC.
Race starts: May 04th 21:30 Registration Open!

▶ Flash

GO TO RACE

Bay to Bay 2024 - Leg 1 - Great Sandy Strait

Prepare for an adrenaline-packed race as the pristine waters of the Great Sandy Strait beckon for a thrilling showdown! This first race of our two-race series stretches over an amazing 16-nautical-mile course, with our skilled sailors at the helm of their Seascape 18s. With fierce competition and a fantastic post-race BBQ awaiting our sailors at the finish line, what more could we ask for?! Brace yourself for a fascinating adventure and we look forward to seeing you at the start line!
Race #1801
INFO from brainaid.de
Seascape 18 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: B2B - SYC
RACE CLOSE: Tuesday,
May 7 at 2300 UTC.
Race starts: May 04th 01:00 Registration Open!

▶ Flash

GO TO RACE

Melbourne to Osaka Prelude 2024

Welcome once again to what these days is Sailonline’s almost annual virtual Melbourne to Osaka Yacht Race. In real life, this double-handed 5500 nm race between these two sister cities, one deep in the southern hemisphere, the other high in the northern hemisphere, is run every four to five years, and is planned to be held again in 2025, so this race is a Prelude in partnership with the Melbourne Osaka Cup 2025 organising committee collaborating with the Ocean Racing Club of Victoria (ORCV), and the Sandringham (SYC) and Osaka Hokko (OHYC) yacht clubs. On this occasion, we’ll be racing the well-known First 40, a popular size of boat for a long-distance double-handed race. With the doldrums unavoidably lying across the track, you can expect to be at virtual sea for at least a month!
Race #1669
INFO by brainaid.de
First 40 Particulars
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: SYC
Race starts: Apr 20th 00:00 Registration Closed

▶ Flash

GO TO RACE

Go to race archive

SYC Ranking

View full list

Series

Mobile Client

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

The mobile client