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 Support » Something weird happened at Sydey TSR

Posted by
JakeS


Users avatar

Posts
18
Registered at
2012-09-25 16:23:40
2013-10-09 17:02:40 - Something weird happened at Sydey TSR
I try to set my boat to cog 262.2... (to get to pr start) and that kind of predictor line came up (see pic). I try twice, same both times . . . and as you can see my bs is -0,03 and twa is 51.65 :)
Attachments
Posted by
RainbowChaser


Users avatar

Posts
2656
Registered at
2009-06-14 09:44:50
2013-10-09 17:11:37 - Re: Something weird happened at Sydey TSR
As discussed in race chat - there is nothing weird (fortunately)... its just how tall ships are. Best VMG is around + / - 72d :-)
________________

--- Last Edited by RainbowChaser at 2013-10-09 17:12:16 ---
Posted by
JakeS


Users avatar

Posts
18
Registered at
2012-09-25 16:23:40
2013-10-09 17:19:34 - Re: Something weird happened at Sydey TSR
Sorry my mistake. Was just thinking that twa +50 usually move you boat forward not backward. Did not remember that we sail by TSR boats :)
Posted by
kroppyer


Users avatar

Posts
347
Registered at
2010-02-05 15:25:55
2013-10-09 18:08:00 - Re: Something weird happened at Sydey TSR
The square rigger polar contains negative speeds. This was, as far as I can tell, not intended. I think it's a result of the spline calculation that was used to create the polar. The designer probably set some values like
twa -> sog
0 -> 0
20 -> 0
40 -> 0
55 -> 0
60 -> 0.3
65 -> 2.3
70 -> 4.3

And then the computer was used to make a smooth line through these points to determine the values in between. The algorithm that did the smoothing was not told it could not use negative values to make the line smooth.

Tall Ships are probably the only polars that have this, as no other boat would have a SOG of 0 when TWA != 0

.. ok, that was a poor explanation... but I added a nice colourful picture to make you all happy again :)
It's the polar, zoomed in to the centre, you can see the loops that were the result of the spline calculation.

--- Last Edited by kroppyer at 2013-10-10 05:10:39 ---
Attachments

Please login to post a reply.

Races

Next Race: 00d 00h 00m

Current Races:

Red Eye - Melville Island PYOC 2026

Melville Island is the largest of the Tivi group opposite the port of Darwin in the Timor Sea. Tropically forested and thinly populated, not a lot goes on there, but let’s race around it anyway, lar- or starboard round, it’s a little more than 120nm, so, no matter where you are navigating from on the planet, you will be hard-pressed to complete the course aboard your J-80 in daylight hours!
Race #2003
INFOby brainaid.de
J-80 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: RED - SYC
Race starts: Mar 24th 12:00 Registration Open!
▶ Flash
GO TO RACE

Cross the Convergence 2026 - Guam to Ouvéa


The third race of our series of ocean voyages across the World’s convergence zones takes us southeastward now down the Pacific, from Guam’s Apra Harbour at 13.5 degrees North, back across the Equator to the glorious New Caledonian resort island of Ouvéa, on the edge of the Tropic of Capricorn at 20.5 degrees South. It’s 2400nm, and there’s more than a few other islands in the way, so mind where you go in your Ocean 50s. Race #1981
INFOby brainaid.de
Ocean 50PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: CCZ - SYC
Race starts: Mar 20th 18:00 Registration Open!
▶ Flash
GO TO RACE

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 Open!
▶ 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 CLOSE: Tuesday,
March 24 at 2300 UTC.
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 CriticalHippo
  7. Sailonline Yacht Club Member vida
  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