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:

Lake Victoria TIMED Race 2026

This month’s TIMED race takes us inland to Lake Victoria in the heart of Africa. Starting at Rosebery Channel in Uganda sail the AC72v2 on a 196nm course around Bugala Island on the way to the finish line in Tanzania’s Speke Gulf. This is a TIMEDrace so you may RE-REGISTER HEREto try again after finishing a run. You will have 13 days and 11 hours to test your skill and decision making after the race opens.
Race #2018
INFOby brainaid.de
AC72v2 Particulars
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking:
TRQ1 - TRCH - SYC
RACE CLOSE: Saturday,
28 March at 23:00 UTC
Race starts: Mar 15th 12:00 Registration will open soon
▶ Flash
GO TO RACE

SSANZ Round North Island Race 2026 - Leg 4

The final challenge awaits in Leg Four of the Round North Island Series! From Napier, the fleet sets off on a 354 nautical mile run back to Auckland, completing the full circumnavigation where the journey began. Fatigue may be setting in, but this last leg could decide the overall standings. Sailing the fast and responsive Sun Fast 3600, our skippers will need sharp tactics and steady focus to finish the series strong and claim victory!

The start time for this race may change at short notice to align with the real race. The confirmed start date and time will be announced via an in-race “L” flag message — Please monitor race communications closely.
Race #2014
INFO by brainaid.de
Sun Fast 3600 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: RNI - SUPBUD - SYC
Race starts: Mar 12th 22:00 Registration Open!
▶ Flash
GO TO RACE

SSANZ Round North Island Race 2026 - Leg 3

Leg Three of our Round North Island Series, in partnership with SSANZ, keeps the pressure on! From Cook Strait, the fleet turns north for a 187 nautical mile passage up the east coast to Napier. It may look like a quick overnighter, but shifting coastal winds and the ever-lively Cook Strait demand sharp focus. In our responsive Sun Fast 3600s, a proven short-handed racer and powerful downwind performer, tactical decisions and precise timing will make all the difference!

The start time for this race may change at short notice to align with the real race. The confirmed start date and time will be announced via an in-race “L” flag message — Please monitor race communications closely.
Race #2013
INFO by brainaid.de
Sun Fast 3600 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: RNI - SUPBUD - SYC
Race starts: Mar 08th 22:00 Registration Closed
▶ Flash
GO TO RACE

Iceland to the Falklands 2026

Welcome to an all-new route, the first of three Round the 'Old World' of Europe, Africa, Australia and Asia. To give each leg of the ROW a bit of length we'll try to hug the coasts as little as possible, so starting in Iceland our first leg of the series, which will also be the final leg of our Quarter 1 Ocean Championships takes us 7200nm to the Falklands, the full length of the Atlantic end to end. To make sure we'll get it done within the month we'll be sailing our Maxi Trimaran.
Race #2010
INFO by brainaid.de
Maxi Trimaran PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: OCQ1 - ROW - OCCH - SYC
Race starts: Mar 02nd 11:00 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 rafa
  4. Sailonline Yacht Club Member rumskib
  5. Sailonline Yacht Club Member Sax747
  6. Sailonline Yacht Club Member vida
  7. Sailonline Yacht Club Member CriticalHippo
  8. Sailonline Yacht Club Member CollegeFund
  9. Sailonline Yacht Club Member Panpyc
  10. Sailonline Yacht Club Member sassy63

View full list

Series

Mobile Client

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

The mobile client