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 » RRS rules about mark roundings

Posted by
Rod


Users avatar

Posts
392
Registered at
2010-06-24 22:30:48
2015-06-23 20:21:39 - RRS rules about mark roundings
28.2 A string representing a boat’s track from the time she begins to
approach the starting line from its pre-start side to start until she
finishes shall, when drawn taut,
(a) pass each mark on the required side and in the correct order,
(b) touch each rounding mark, and
(c) pass between the marks of a gate from the direction of the
previous mark.
She may correct any errors to comply with this rule, provided she has
not finished.

This was in response to a question that arose in the Practice Race at Kiele on 23 June 2014.
Do the SOL rules state it the same?

--- Last Edited by Rod at 2015-06-23 20:40:08 ---
If it breaks, it's not strong enough--if it doesn't, it's too heavy.
Posted by
kroppyer


Users avatar

Posts
347
Registered at
2010-02-05 15:25:55
2015-06-23 23:25:51 - Re: RRS rules about mark roundings
No.

One difference is that sol uses rhumb lines between marks. I'm sure that when drawing this imaginary string taut, it would follow a GC line, not a rhumb line. There might be more differences (I'm not sure because I find the RRS rule ambiguous).

In sol the course to be sailed in drawn on screen, order of roundings and direction of roundings is clear. While racing you can either round the next mark, or unround the previous, other marks are not in play.

Unrounding happens* when you cross the rounding line in the wrong direction and after crossing you've crossed the rounding line as many times in the correct direction as in the incorrect direction.

Rounding happens* when you cross the rounding line in the correct direction and before crossing you've crossed the rounding line as many times in the correct direction as in the incorrect direction.

Say we have marks A, B, C (in that order), then the rounding line of B is a line starting at B, moving away from A, B and C. Additionally, the rounding line lays on the bisector of angle ABC.

*) This is how I understand it should happen. I'm not entirely sure that this is the case when you sail multiple laps around the mark.

In any case, you should be able to round your next mark by sailing around it in the correct direction until it says "rounded", i.e. there's no "going in the wrong direction to unround". If you have trouble rounding the mark, it means you've already rounded in the wrong direction, all that's left is sailing around the mark in the correct direction.

----

Two more things:
- I don't like the RRS wording/theory.

- PRs are different.

--- Last Edited by kroppyer at 2015-06-23 23:34:20 ---
Posted by
Rod


Users avatar

Posts
392
Registered at
2010-06-24 22:30:48
2015-06-29 01:35:48 - Re: RRS rules about mark roundings
My interest stemmed from a consideration of the logic behind ANY mark rounding rule on the computer. If the SOL rule was to be applied to a spherical Earth, the projected 'rounding line' would circle the Earth and enter the mark from the rear, thus making the "miss, return and round correctly" of the RRS impossible. The field of action would have to be limited in total area to make it possible.
If the map used was to be a Mercator's projection, then no area limitation would be required.
In the case in point, if the turn mark had been just a small distance (3 pixels?) off shore, then the island could indeed have been rounded the "wrong" way,and all requirements for a successful rounding could have been met.
If it breaks, it's not strong enough--if it doesn't, it's too heavy.
Posted by
kroppyer


Users avatar

Posts
347
Registered at
2010-02-05 15:25:55
2015-06-29 13:00:55 - Re: RRS rules about mark roundings
Rounding lines in SOL are loxodromic (straight on Mercator projection). This has previously resulted in some weird DTF numbers. It is indeed very hard to define rounding a mark on a sphere. Gates almost always work, so I'd say that rounding a mark is similar to sailing through a gate with the mark to be rounded on one side, and some point on the course boundary on the other.

If there is a mark 3px offshore from an island, and only the rounding direction of the mark is specified (nothing about the island), you could indeed round the mark correctly, while 1) not rounding the island or 2) rounding is opposite to the mark. Sol doesn't work with islands that way. If we want to have a course round an island, we place the mark on the island, forcing your to round the entire island.

Please login to post a reply.

Races

Next Race: 00d 00h 00m

Current Races:

Africa by Sea - Swakopmund to Maputo 2025


Time again to continue our exploration of Africa by Sea, which now takes us around the tip of the continent at Cape Agulhas and up the coast of South Africa to Mozambique’s marvellous Maputo, where we should find good anchorage in the bend of the Rio Espirito Santo (Umbuluzi) once we’ve cleared the 60m high Maputo - Katembe suspension bridge. It’s 1900nm and we’ll be glad to be sailing our comfortable and sturdy Xp-55, as we will certainly experience more headwinds!
Race #1857
INFOby brainaid.de
Xp-55 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: SYC - ABC
Race starts: Jun 11th 17:00 Registration will open soon
▶ Flash
GO TO RACE

Isle of Wight RTI Sprint 2025


Welcome to the Isle of Wight in the British Isles. A past home to Queen Victoria and the foundation of the America's Cup when yacht racing became popular in the 1800's. This particular race was last raced on SOL in 2012 to follow Soler JuJu sailing around the island. We return, long overdue, to race our final Q2 sprint around the island.
Race 1918
INFO by brainaid.de
Ker 40 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking:
SPRQ2 - SPRCH - SUPSOL – SYC
Race starts: Jun 07th 09:00 Registration Open!
▶ Flash
GO TO RACE

Marquesas to Young Island 2025

The adventure continues as we launch this fourth leg of the RWW series, racing from Marquesas to Young Island in the Balleny Islands, a group of islands in the Southern Ocean only 62 nm from Antarctica. Get ready for a chilling new challenge as we set sail on the sixth leg of the 2025 Ocean Championship Series! A 4100nm journey of endurance, strategy, and pure sailing excitement. This leg will be pursued aboard the race machine RP66, pushing sailors to their limits. Do you have what it takes to conquer the Southern Ocean? Join us and put your skills to the ultimate test!
PRIZE: SMPF
Race #1909
INFO by brainaid.de
Raichel/Pugh 66 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: OCQ2 - RWW - OCCH - SUPSOL - SYC
Race starts: Jun 02nd 11:00 Registration Open!
▶ Flash
GO TO RACE

TuziTekwini TIMED Race 2025

Sailonline is delighted to have been invited to partner with the King Shaka Yacht Club (KSYC) of South Africa to bring a virtual version of the Tuzi Tekwini Ocean Raceto our online community.
The Tuzi Tekwini Ocean Race is a near 90 nautical mile race down the east coast of South Africa from the port of Richards Bay to the port of Durban. Achievable in a single day and seen by some as an easy mile-builder, the course is more tactical than some think and should not be underestimated. This iconic race promises to be an unforgettable experience for yachting enthusiasts.
Our online version of the race will be 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 #1916
INFOby brainaid.de
Sailonline’s virtual yacht for all your runs will be our much-loved Farr 38 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking:
TRQ2 - TRCH - SUPSOL - SYC
RACE CLOSE: Saturday,
14 June at 23:00 UTC
Race starts: Jun 01st 12:00 Registration Open!
▶ Flash
GO TO RACE

SoCal 300 2025


With this year's 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 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 #1919
INFO by brainaid.de
Santa Cruz 52 PARTICULARS
NAM_AWIP WX Updates:
0245 / 0845 / 1445 / 2045
Ranking: SYC
RACE CLOSE: Sunday,
June 8 at 2300 UTC.
Race starts: May 29th 20:00 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 FreyjaUSA
  5. Sailonline Yacht Club Member Patrick70119
  6. Sailonline Yacht Club Member Kipper1258
  7. Sailonline Yacht Club Member rafa
  8. Sailonline Yacht Club Member rumskib
  9. Sailonline Yacht Club Member Smo
  10. Sailonline Yacht Club Member bonknhoot

View full list

Series

Mobile Client

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

The mobile client