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 » MOD70 polar development

Page: Previous 1 2 3 4 Next

Posted by
SlashV


Users avatar

Posts
14
Registered at
2009-08-09 22:01:21
2012-12-26 00:33:49 - Re: MOD70 polar development
I've made the following approximation for the krys map:
lat = -2.855E-7 * x^2 - 0.002296592 * x + 69.251568
lon = 0.008093847 * y - 150.31126
Posted by
Tarco


Users avatar

Posts
41
Registered at
2011-11-09 21:54:22
2012-12-26 00:51:55 - Re: MOD70 polar development
This is my first draft : a BWR polar
I think timings are close to what happened, except in Euro-Leg 4, trajectories are not always right, though....
It still needs some corrections.

Don't use for navigation !!! :-)

--- Dernière modification par Tarco le 2012-12-26 00:52:59 ---
Attachments
Posted by
SlashV


Users avatar

Posts
14
Registered at
2009-08-09 22:01:21
2013-01-13 04:24:06 - Re: MOD70 polar development
OK, found some time :) and created a script to parse the addviso xml files and 'enrich' the results with data from the grib files.
I will try to come up with a least squares fit for curves to match the data. Anyone know good basis functions for this?
I am curious how this will turn out. The data doesn't look particularly 'neat'. I attached some plots.
@Tarco. I'll have a look at your file as soon as I have some results of my own.
Attachments
Posted by
76Trombones


Users avatar

Posts
362
Registered at
2009-08-03 18:04:56
2013-01-14 15:28:00 - Re: MOD70 polar development
Those look great. Immediate impressions are of deeper vmg downwind and even more light wind speed. It looks like there are interesting things going on headsail reaching as well.
Posted by
Tarco


Users avatar

Posts
41
Registered at
2011-11-09 21:54:22
2013-02-07 20:09:44 - Re: MOD70 polar development
Back after a month...
Is it only me ? I don't have access to Krys Ocean race tracker anymore...

My impression : when they pinch (TWA35), they are able to keep the speed they have build. When they haven't build the speed, they stay at half-ish the top speed they can reach.
That makes 2 sets of speed at low TWA. One set at almost twice the wind speed when they have build the top speed, coming from higher TWA and another set of "low" speed when the speed is not built yet... don't know if I'm clear...
That could probably be simulated by keeping the high speed with a huge loss of speed (50 % or so) when tacking at TWA 50 or less. Or maybe take a top speed of 3/4 of sample speed...

Back to sampling Euro Tour before it disappears too... New results in a few days.
Next races will be in june (Euro Tour) then October 2013 (World Tour in legs)

Posted by
Tarco


Users avatar

Posts
41
Registered at
2011-11-09 21:54:22
2013-04-18 21:04:42 - Re: MOD70 polar development
Back again...
All the trackers have disappeared, so I can't go on with the calcs....

Here are the results I got, up to now. (see attached)

Between brackets, the number of occurences.
When I found several results, too different one from the other, I kept both.

I hope a polar can be created from that.
Attachments
Posted by
76Trombones


Users avatar

Posts
362
Registered at
2009-08-03 18:04:56
2013-04-18 22:12:00 - Re: MOD70 polar development
Looks good Tarco - I think we probably have enough data for a good guess. I can help bring it all together, or would you like to do the honours?

They'll be racing the "Route des Princes" in June as 4 shorter legs around Europe. We might not be able to fit all legs in (though it would make a nice series). RC probably has an idea of what's on deck for June, but it's always a busy month. Even if we don't do them in SOL we can "race" the new polar as a final check.

The *big* race will be the Transat in November? I hope they all make it to the start.
Posted by
RainbowChaser


Users avatar

Posts
2656
Registered at
2009-06-14 09:44:50
2013-04-18 22:30:18 - Re: MOD70 polar development
The SOL Racing Year shows what we have pretty much committed to in June .. it is a busy month... but if you can find a way to fit these new races in please feel free to do so! I am all for new ventures :-)

Are the races already in bed with a virtual sailing platform? If so, then that is another issue to be "managed" :-)
Posted by
Tarco


Users avatar

Posts
41
Registered at
2011-11-09 21:54:22
2013-04-19 09:04:39 - Re: MOD70 polar development
I would really love to build the SOL polar.

As June is already overbooked, we should probably not try to run the Princes races. But we can use them to compare the "predicted" speeds to the real ones. They will probably publish a real time tracker on line.
Probably a good way to make corrections to the 'prototype'.

Then, maybe, run a short race in September as a warm-up for crews before the Atlantic race in November. The polar should be ready by then.

The only problem is that "How to create SOL polar for dummies" is not published yet... :-)
I'll probably (certainly) need some help... :-)
Posted by
Tarco


Users avatar

Posts
41
Registered at
2011-11-09 21:54:22
2013-04-24 06:20:19 - Re: MOD70 polar development
76T, on second thought, I reckon you should create the "guessed" polar, so we could try it on a short race in may. And compare it to the real "Route des Princes" legs in June.

I believe that would take you a few hours when I would need weeks, if not more, just to understand how to do...

But I would like you to explain me afterwards, if you've got time to. :-)


--- Dernière modification par Tarco le 2013-04-24 09:49:59 ---

Page: Previous 1 2 3 4 Next

Please login to post a reply.

Races

Next Race: 00d 00h 00m

Current Races:

Isle of Mull TIMED Race 2026

Welcome to the west coast of Scotland for an 80 nm race around the Isle of Mull. Mull is home to castles, distilleries, and the Highland Games. The race begins just north of Oban in the shadow of Dunstaffnage Castle and after rounding the island finishes down the coast at Crinan. The Twister 28 with its classic long keel is the boat for this race.
This is a TIMEDrace so you may RE-REGISTER HEREto try again after finishing a run. You will have two weeks to test your skill and decision making after the race opens.
Race #2057
INFOby brainaid.de
PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking:
TRQ3 - TRCH - SYC
RACE CLOSE: Saturday,
26 September at 23:00 UTC
Race starts: Sep 13th 12:00 Registration will open soon
▶ Flash
GO TO RACE

Cross the Convergence 2026 - Cocos to Sagar Island


Kapil Muni, incarnation of Lord Vishnu, founder of the Samkhya school of philosophy, disturbed from his meditation, in his wrath reduced the 60,000 sons of Sagar to ashes, as they dug the earth to retrieve the sacrificial horse that Lord Indra, the king of the Gods, stole off Sagar, thus creating the Sagara (ocean). Aeons later, Bhagiratha, a descendant of Sagara, asked Ganga to cleanse the ashes of the 60,000 princes, and her resultant torrential fall from heaven created the great river and where it met the ocean, the princes’ souls were washed and raised to heaven and Gangasagar (Sagar Island) was formed. So, let us join the pilgrimages to Kapi Muni’s Temple (see above) and race 2400nm from Cocos Island deep in the Sagara thence, in rather rapid Rapido 60s.
Race #1987
INFOby brainaid.de
Rapido 60PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: CCZ - SYC
Race starts: Sep 11th 18:00 Registration Open!
▶ Flash
GO TO RACE

The Vineyard Race 2026


For the 16th consecutive year, our SOLers are invited to tackle this iconic 250nm overnighter. The classic route charges out through the sound, leaves Buzzards Bay Light to starboard, rounds Block Island to starboard, and heads home.

This year's weapon of choice is the Beneteau First 47.7. A proven performer since its 2012 SOL debut, this Farr-designed cruiser/racer excels at leading real and virtual handicap fleets. Success will demand sharp tactical navigation, so watch the polars closely to conquer the sound's shifting winds!
Race #2056
INFO by brainaid.de
First 47.7 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: SUPBUD - SYC
Race starts: Sep 04th 17:05 Registration Closed
▶ Flash
GO TO RACE

Shearwater - Rio de la Plata to Irish Sea 2026

Welcome to the fourth leg of our MIG series. This time we're racing the Sooty Shearwater on their migration from the breeding grounds in South America to the northern Atlantic. This is also part of our Ocean Championship, and as such the third race of OCQ3 2026. This race will be sailed in our Gunboat 90. Race #2055
INFO by brainaid.de
GunBoat 90 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking:
OCQ3 - OCCH - SYC - MIG
Race starts: Sep 02nd 11:00 Registration Closed
▶ Flash
GO TO RACE

Go to race archive

SYC Ranking

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

View full list

Series

Mobile Client

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

The mobile client