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 » Timing Course Changes

Posted by
bonknhoot


Users avatar

Posts
110
Registered at
2013-08-06 21:35:15
2014-05-04 13:17:52 - Timing Course Changes
Just read Roland Stoerte's report on the B2B2 of last night. As he wrote it was all about 'rounding' and a minor tactical decision for the close-hauled bit to the finish: pinch or put in a tack. Roland writes about 'counting' to know when to press 'send command'. How does that work, anybody?
During my short SOL career I have developed a quite different approach to the dilemma of 'timing'. I found a few VBA UDF's on the net which return course and distance between two lats and lons. So I enter the relevant lats and lons into a spreadsheet before a race (or as I go along) and then copy and paste time of day, speed and position over from BrainAid (ever more frequently) as I close on a buoy or a cape or a shore. If BrainAid's data is fully synced, then my spreadsheet returns me my exact ETA to the next manoeuvre, except of course that speed may change as I progress and that I may be on a TWA curve and not a COG straight line. Editing the pre-set DC then completes the process and with 30 secs to go I just sit back and wait. It continues to surprise how much the calc'd ETA varies from one sample to the next. Even with just two or thee minutes to the mark and no noticeable speed variation (e.g as a result of performance recovery perhaps) the swings are often order of mag 5 to 10 secs. An element of luck and a trade-off risk v reward thus remains. So... does BrainAid provide a wholly accurate sync'd sample of a SOL yacht's data, or... ?
Thoughts anybody?
Clipping along
Posted by
kroppyer


Users avatar

Posts
347
Registered at
2010-02-05 15:25:55
2014-05-04 19:34:55 - Re: Timing Course Changes
SOL's normal client updates your own boat position every 15 seconds, and requests its data directly from sailonline.

brainaid's navigation page updates boat data roughly every 10 seconds, and requests its data from brainaid.de (which probably gets its data, without caching, from sailonline).

Sailonline recalculates the position of your boat with a variable interval. My experience is that this interval is usually 10 seconds.

This means that, using sol's client, you will see your boat move every 15 seconds (maybe in a rare case, 30 seconds). If you see you have only one jump left to the mark, you can count to 10, and then turn, assuming the server already jumped, but before the client updates. This can go wrong.

Sometimes I get the feeling that commands are executed in-between two jumps (boat turns less than a single jump-length from my last position). Sometimes, even after 10 seconds, my boat turns at its last position, 5 seconds later the client updates and shows a track that suggests my boat turned 10 seconds earlier than I sent the command.

If you set a good DC, with some margin (and do not adjust it using the DC countdown, unless you are sure your local clock is in sync with sailonline), your boat often does a good rounding.

For now, I think the best method is:
set a reasonably safe DC (like 10 seconds after the mark), then try to beat that manually, using your preferred method (counting, instinct, visual, confidence, praying, persuasion of sol server, telekinesis).

Turning you boat at an exact place is hard, and I think part of a good rounding is not only getting your boat to turn where you want it to turn, but also accepting that you can't do that, and solving it differently: leave some room to the mark (or land), turn about one jump before you're at the mark so that you touch the mark (this needs practise). You will sail past the mark with a better angle: the distance you travel after the mark is not as much in the wrong direction as usual. When you can, of course, complete the turn.


This is how accurate DC roundings can be:


--- Last Edited by kroppyer at 2014-05-04 20:11:18 ---
Attachments
Posted by
JB


Users avatar

Posts
305
Registered at
2013-03-07 08:54:34
2014-05-05 07:57:38 - Re: Timing Course Changes
Viva Jan and Kroopy.

Not long ago in this forum I’ve put some words about my frustration precisely about this issue.
So, I’m totally in tune with both.
My conclusions were/are simple.
Instead of a precise boat maneuver, trying to turn where you need and want, it’s an act of pure luck and/or faith.
For the same “sail engine” input conditions (TWD/TWA/TWS) the same boat has, sometimes, makes different consecutive jump lengths and, even in the same run, different ones.
So, I discovered also that my boat has free will, challenging logic, laws of kinematics, accuracy and, in last ratio, the patient of the sailor.

In long races, unless you are close to a competitor, it doesn’t make a big difference or, any at all.
In TR’s, where go “cutting the corners”, it can result in loss of several places.

Yes, we have to accept that “luck” is part of the sport, but it shouldn’t be here applicable.

There are two (cumulative, or not) solutions for this problem:

1 - Effective DC’s - function of remaining distance and B.S., the boat changes direction in the precise calculated time, as it should be;
2 - Waypoints - the boat changes direction on previously defined marks, independently of all the prevailing conditions.

The same lack of accuracy can be pointed to the famous “jumps over land”.
I was in shock when it happened to me.
Again, it shouldn’t.

Big Hug from
João
Sail Fair.
Posted by
Rod


Users avatar

Posts
392
Registered at
2010-06-24 22:30:48
2014-05-05 16:14:57 - Re: Timing Course Changes
The above entries describe very closely my own experience and complaints about the precise point and time at which course changes are executed. I also have not,(so far?) been able to determine any "formula" which describes the process.
My question here, as a "non-user-of-routers", and observing the superior performance of those who do use them, is whether these routers have SOLVED this problem. Am I merely penalizing myself and my SOLing performance by refraining from their use, just to keep tuned the "old grey cells"?
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
2014-05-05 21:20:32 - Re: Timing Course Changes
Rod,

Most* routers are useless in these short races. To speed up the routing process they use "jumps" of much more than 10 or 15 seconds. So they certainly do not help you rounding marks (or at least, not when you can't lose a few minutes).

*) I say "most" because I can't pretend to know "all" routers. Maybe there is a router, specifically made for online sailing, that is able to use very small jumps.
Posted by
Rod


Users avatar

Posts
392
Registered at
2010-06-24 22:30:48
2014-05-06 02:23:05 - Re: Timing Course Changes
I will continue to exercise the "old grey cells"---in the vague hope that they will become "young" grey cells----if I could just remember 'how' to do it......

--- Last Edited by Rod at 2014-06-27 16:28:18 ---
If it breaks, it's not strong enough--if it doesn't, it's too heavy.

Please login to post a reply.

Races

Next Race: 00d 00h 00m

Current Races:

Easter Island to Tristan da Cunha 2026

Welcome to the second leg of our RNW series, rounding Cape Horn. This middle-most leg Round the New World, from Easter Island to Tristan da Cunha, is also part of our Ocean Championship, and as such the second race of OCQ3 2026. This race, like the previous race in the RNW series, will be sailed in our revised 'version 2' Imoca 60 Foil. Race #2050
INFO by brainaid.de
Imoca 60 Foil v2 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: OCQ3 - RNW - OCCH - SYC
Race starts: Aug 03rd 11:00 Registration Open!
▶ Flash
GO TO RACE

Magical Mediterranean 2026 - Benghazi to Korcula

We return to Antiquity’s Middle Sea for a seventh celebration of all things Mediterranean - fickle winds, history and olive oil. This time we will sail from ancient Benghazi, whence once grain shipped continuously to feed Rome’s urban masses, to the medieval Venetian thalassocracy’s port of Korcula, birthplace of Marco Polo; 700nm in classy Club Swan 50s!
Race #1978
INFO by brainaid.de
Club Swan 50 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: MED - SYC
RACE CLOSE: Friday,
August 7 at 2300 UTC.
Race starts: Jul 27th 15:00 Registration Closed

▶ Flash
GO TO RACE

Red Eye 2026 - Georgian Bay

Welcome to the sensational scenic Georgian Bay of northern Lake Huron, the first area of the Great Lakes to be visited by Europeans in 1615, so former SOLer A2R informed us when he designed this geometrically tortuous course of 317nm criss-cross through its island maze. Originally known as Lake Manitoulin, in 1822 the bay was renamed after King George IV after his succession to the throne. This time we’ll take the very flashy Fareast 31R, which hopefully should keep you wide awake!
Race #2051
INFOby brainaid.de
Fareast 31R PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: RED - SYC
RACE CLOSE: Monday,
August 3 at 2300 UTC.
Race starts: Jul 26th 08:00 Registration Open!
▶ Flash
GO TO RACE

Tall Ships 2026 - Stavanger to Aalborg


Welcome to the fourth of four virtual Tall Ships Races in European waters which are concurrently being organized in-real-life by Sail Training International . This fourth race is from Stavanger in Norway into the Skaggerak to a finish off Denmark’s Aalborg and perhaps an Aquavit to toast the adventure afterwards – a final circa 250nm in Sailonline’s classic Clipper 240.
NOTE: Starts and Finishes in tall ships racing are always offshore to avoid conflict with shipping and shipping lanes; online and real-life may not match exactly.
Race #1995
INFO by brainaid.de
Clipper 240 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: TSI - SUPBUD - SYC
Race starts: Jul 25th 16:00 Registration Closed
▶ Flash
GO TO RACE

Chinook Salmon - Canada to Andreanovs


A year after spawning in the upper reaches of the rivers of British Columbia, Chinook Salmon develop the age-old urge, so familiar to SOLers, to go to sea, heading for different parts of the northern Pacific Ocean. This race catches up with a particular school with an instinctive memory for the Andreanov Islands far west on the Aleutian Islands chain, as they depart the Salian Sea between Vancouver Island and the San Juans. It’s 2200nm and we’re taking the 60ft Trimaran, in the hope we can keep up!
Race #2048
INFOby brainaid.de
60ft Trimaran PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: MIG - SYC
Race starts: Jul 21st 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 CriticalHippo
  4. Sailonline Yacht Club Member Panpyc
  5. Sailonline Yacht Club Member rafa
  6. Sailonline Yacht Club Member cdhinman
  7. Sailonline Yacht Club Member rthinman
  8. Sailonline Yacht Club Member ms0689
  9. Sailonline Yacht Club Member BRENTGRAY
  10. Sailonline Yacht Club Member Sax747

View full list

Series

Mobile Client

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

The mobile client