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
106
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:

Nantucket Sprint 2025


Welcome to Nantucket, from whence Herman Melville’s Cap’n Ahab sailed round The Horn into the northern Pacific Ocean to hunt the gray whale - whose migrations are celebrated elsewhere in SOL’s Q4 schedule - he never to return. And whaling too, as the 19th C progressed, like Ahab disappeared from Nantucket as the harbour silted up and mainland Massachusetts whaling stations benefited from rail connections. But beach life, yachting and nostalgia has rescued the island from oblivion, so to celebrate leisure, SOL gives you the Nantucket Sprint - 25nm in 29er_XX’s from Great Point to Muskeget & Tuckernuck Islands across the sound to a finish just inside the mouth of the harbour. Enjoy!
Race 1936
INFO by brainaid.de
29er_XX PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking:
SPRQ3 - SPRCH - SUPSOL – SYC
Race starts: Jul 19th 15:00 Registration will open soon
▶ Flash
GO TO RACE

Tall Ships Races 2025 - Dunkirk to Aberdeen


Welcome to the second of four virtual Tall Ships Races in European waters which are concurrently being organized in-real-life Sail Training International . This second race is from Dunkirk in France up the North Sea to Scotland’s Aberdeen; circa 400nm in Sailonline’s magnificent 90m Barque.
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 #1924
INFO by brainaid.de
Barque 90m PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: TS - SYC
RACE CLOSE: Tuesday,
July 22 at 2300 UTC.
Race starts: Jul 13th 16:00 Registration Open!
▶ Flash
GO TO RACE

Suursaari TIMED Race 2025

The first TIMED race of the northern hemisphere Summer takes us to the Gulf of Finland on a 165nm zig-zagging course beginning and ending in the seacoast village of Haukilahti and circling the island of Suursaari. It’s only appropriate that the boat for this race is Finland’s own Club Swan 50. 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 #1928
INFOby brainaid.de
PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking:
TRQ3 - TRCH - SUPSOL - SYC
RACE CLOSE: Saturday,
26 July at 23:00 UTC
Race starts: Jul 13th 12:00 Registration Open!
▶ Flash
GO TO RACE

Lake Ontario 300 Challenge 2025

Lake Ontario Offshore Racing (LOOR) welcomes Sailonline sailors (SOLers for short) to a second virtual version of a race in their annual series, the LO300. As the name implies, the LO300 is a 300nm offshore race across the length and breadth of Lake Ontario, from and back to Port Credit YC. Once again, as is our wont on Lake Ontario, a fleet of Beneteau First 36.7s is being made available to virtual racers. There is an overall prize for the SOLer who best bosses Lake Ontario over the two races hosted by Sailonline, this 300 and the Susan Hood raced back in May; so, let the competition be fierce!
Race #1931
INFOby brainaid.de
First 36.7 PARTICULARS
NAM_AWIP WX Updates:
0245 / 0845 / 1445 / 2045
Ranking: LOOR - SYC
RACE CLOSE: Wednesday,
July 23 at 2300 UTC.
Race starts: Jul 12th 15:10 Registration Open!

▶ Flash
GO TO RACE

Young Island to Great Nicobar 2025

The adventure continues as we launch this fifth leg of the RWW series, racing from Young Island to Great Nicobar on the edge of the Bay of Bengal. Get ready for a chilling start as we set sail on the seventh leg of the 2025 Ocean Championship Series! A 5200nm journey of endurance, strategy, and pure sailing excitement. This leg will be pursued aboard the Super Maxi 100v2, pushing sailors to their limits. Do you have what it takes to conquer the Indian Ocean? Join us and put your skills to the ultimate test!
PRIZE: SMPF
Race #1929
INFO by brainaid.de
Super Maxi 100 v2 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: OCQ3 - RWW - OCCH - SUPSOL - SYC
Race starts: Jul 07th 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 WRmirekd
  3. Sailonline Yacht Club Member KaSToR
  4. Sailonline Yacht Club Member rafa
  5. Sailonline Yacht Club Member Kipper1258
  6. Sailonline Yacht Club Member FreyjaUSA
  7. Sailonline Yacht Club Member vida
  8. Sailonline Yacht Club Member BRENTGRAY
  9. Sailonline Yacht Club Member rumskib
  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