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 Discussion » Gribs

Posted by
bonknhoot


Users avatar

Posts
109
Registered at
2013-08-06 21:35:15
2019-03-06 07:45:49 - Gribs
When the Sardinia Cup opened yesterday, some racers noted that the wrf gribs outside the racing area and out to the weather system looked odd, and they do, and they always have done. As we do not sail there and the software that modulates the synoptic forecasts to generate local so-called 'meso' effects has to do a lot of 'crunching', the wrf gribs that are fed into SOL only cover the racing area. The rest of the weather that you see on SOL or that you download from SOL via brainaid or AGL is generated by the SOL bilinear interpolator. Since between the race area boundary and the weather boundary there is only one piece of data available for interpolation, that being the data at the race area boundary, the result of this interpolation is constant wind out to the weather system boundary and this looks odd especially if the weather system boundary is a long way 'out'. Those of you mathematically-minded may well wonder why does the weather not reduce linearly to 0 at the edge, then. Well, because that's not how the algorithm is written.
Some of you may also wonder why we show weather out beyond the race area at all. The reason for that is that the predictor line(s) pointing out from your bow will go haywire if it/they run(s) out of wind in less than six hours ahead. So we have to have wind six hours ahead at your boat's Vmax at right angles out from the boundary.
As said, it has always been thus, from the very first time we used wrf for the Boston to Newport and then for such iconic SOL perennials like Pacific North West and The Vineyard and all our Sprints including those in 60kn DN's requiring gribs extending across vast areas of frozen forests, prairies, tundras and the like.
Clipping along

Please login to post a reply.

Races

Next Race: 00d 00h 00m

Current Races:

Susan Hood Trophy Race 2026

Lake Ontario Offshore Racing (LOOR) welcomes racers to Sailonline’s virtual version of their annual Susan Hood Trophy Race. This year, this pleasant weekender on western Lake Ontario will be of about 60nm in length, and online for convenience will start and finish at the Port Credit Yacht Club (PCYC). At or before the real-life Skipper’s Briefing a decision will be made to race the course clockwise (course Delta) or anti-clockwise (Echo). If there is time we will match this online. As before, the race is the first of two that will count towards a special Sailonline's LOOR Series medals, but this year we sail in Jeanneau Sun Fast 3300s. Bon voyage!
Race #2033
INFOby brainaid.de
Sun Fast 3300 PARTICULARS
NAM_AWIP WX Updates:
0245 / 0845 / 1445 / 2045
Ranking: LOOR - SUPBUD - SYC
Race starts: May 29th 23:45 Registration Open!

▶ Flash
GO TO RACE

SoCal 300 2026


With California Offshore Race Week already well under way, here now is your chance to participate virtually in SDYC's challenging 243nm (as the seagull flies) SoCal 300 from Santa Barbara to San Diego. With as ever a wide and wild range of boats entered for the real race, whose progress we hope we will be able to follow on our own chart by linking to the YB tracker, virtual SOLers will have to dig deep to remain competitive in our trusty Santa Cruz 52s.
Race #2036
INFO by brainaid.de
Santa Cruz 52 PARTICULARS
NAM_AWIP WX Updates:
0245 / 0845 / 1445 / 2045
Ranking: SUPBUD - SYC
Race starts: May 28th 20:00 Registration will open soon
▶ Flash
GO TO RACE

Vasco da Gama Ocean Race 2026

Welcome to Sailonline’s virtual Vasco da Gama Ocean Race, in partnership with the Royal Natal Yacht Club’s real-life event. Some 260 nautical miles in length from Durban to East London, the Vasco da Gama is South Africa’s oldest coastal ocean race, and is renowned for the rough seas and strong currents that competitors have to contend with. Online this year we will be racing in slick Salona 39’s. History, endurance, camaraderie – It’s time to honour Vasco’s legacy; see you on the start line!
Race #2034
INFO from brainaid.de
Salona 39 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: SUPBUD - SYC
Race starts: May 24th 08:00 Registration Open!
▶ Flash
GO TO RACE

Cross the Convergence 2026 - St Helena to Cape Verde


The fourth race of our series of ocean voyages across the World’s convergence zones takes us out of the Pacific into the Atlantic for a 2200nm race in Judel Vrolijk 62’s, from the desolation of St Helena, there where Napolean Bonaparte saw out the end of his life, to the even greater desolation of Fogo in the Cape Verde’s. You’ll have to cross the equator, with the coasts of Africa and South America your only navigational restrictions.
Race #1984
INFOby brainaid.de
Judel Vrolijk 62PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: CCZ - SYC
Race starts: May 22nd 18:00 Registration Open!
▶ Flash
GO TO RACE

Tasmania to Kamchatka 2026

Welcome to yet another all-new route. Tasmania to Kamchatka, part of our Ocean Championship and also the third leg of the ROW (Round the Old World) series. Be aware of the obstacles on the way, likely to split the fleet. It's like X:mas to X:mas, crossing the same waters, navigating the same archipelagos. This second race of OCQ2 2026 will be sailed in our revised 'version 2' Imoca 60 Foil. Race #2031
INFO by brainaid.de
Imoca 60 Foil v2 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: OCQ2 - ROW - OCCH - SYC
RACE CLOSE: Tuesday,
June 2 at 2300 UTC.
Race starts: May 04th 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 rafa
  5. Sailonline Yacht Club Member Panpyc
  6. Sailonline Yacht Club Member rumskib
  7. Sailonline Yacht Club Member bonknhoot
  8. Sailonline Yacht Club Member CollegeFund
  9. Sailonline Yacht Club Member vida
  10. Sailonline Yacht Club Member HoratioPugwash

View full list

Series

Mobile Client

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

The mobile client