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 Discussion » Performance loss

Page: Previous 1 2 3 4 5 6 7 Next Last

Posted by
Rod


Users avatar

Posts
392
Registered at
2010-06-24 22:30:48
2013-10-11 01:27:15 - Re: Performance loss
I just did two gybes in a row in the start of the Kergulen timed race. In the first I forgot about the 93% and my perf dropped below 85%. I started the second gybe with a perf of 89% and stepped around in about 4 or 5 steps, completing my gybe at a perf of 90% increasing my perf at each step.
I contend this is vital information that should be known to all, that it cannot be derived by direct observation, or by prior knowledge of how a sailboat performs in reality!
If it breaks, it's not strong enough--if it doesn't, it's too heavy.
Posted by
A2


Users avatar

Posts
347
Registered at
2009-10-26 00:39:42
2013-10-11 13:10:37 - Re: Performance loss
These discussions have occurred in the past but it tends to run in cycles so that when it re-emerges often what was once public knowledge can subside into a quasi state of urban lengend.

Finding these nuggets in this Forum can be a challenge even if you are looking for something that you yourself have posted.

=========================
Wrong Speed VMG

Posted by
Jakob Kuttenkeuler
2009-02-09

(discussing performance loss model)

"Well, the current model determines
if the maneouver is a tack or a gybe
or just a minor change in twa
(dTWA is the twa change).
If (tack or gybe)
{e = 1.0-self.bs/200.0}
else
{e = 1-abs(dTWA)/25.0}.
perf = perf*e.
However if perf<0.93
no further maneouver loss is done. something like that."

--- Last Edited by A2R at 2013-10-11 13:48:19 ---
None so blind
Posted by
Rod


Users avatar

Posts
392
Registered at
2010-06-24 22:30:48
2013-10-11 14:29:14 - Re: Performance loss
Many thanks, A2R!!!!
That is the information that we should have had right at the beginning of this whole discussion. I hope that it will be incorporated in the Manual in a prominent position.
I have inquired about the perf loss problem several times over the last three four years and, until now, never received even a hint of an answer
P.S. I will attempt to generate a diagrammatic representation of this situation for the benefit of those among us who are more comfortable with diagrams than equations.
P.P.S. Now all we need to find out is the rate at which the Performance returns to 100% after a Tack, Gybe, or Course Change.
I do hope someone will post the info---in the meantime I will experiment in the Kergulen screen (there are no good windows in the time remaining.)

--- Last Edited by Rod at 2013-10-11 14:33:17 ---

--- Last Edited by Rod at 2013-10-11 14:41:56 ---
If it breaks, it's not strong enough--if it doesn't, it's too heavy.
Posted by
A2


Users avatar

Posts
347
Registered at
2009-10-26 00:39:42
2013-10-11 14:41:26 - Re: Performance loss
Well depending on your Point of View it was either hiding in plain sight or it was a needle in the haystack, so to speak.

I found it because I went looking for it, plain & simple, as anyone could have done.


None so blind
Posted by
Rod


Users avatar

Posts
392
Registered at
2010-06-24 22:30:48
2013-10-11 14:59:10 - Re: Performance loss
You can only look for things that you suspect do exist. My point is that there is nothing in the performance of a sailboat during a change in course that would lead anyone to suspect that the loss of speed would be reduced by dividing the course change into two steps.
If it breaks, it's not strong enough--if it doesn't, it's too heavy.
Posted by
A2


Users avatar

Posts
347
Registered at
2009-10-26 00:39:42
2013-10-11 15:16:09 - Re: Performance loss
I neither knew that it existed or that it did not exist. Looking is a choice as is not looking. I found more than I expected to, so let's move forward from here.
None so blind
Posted by
captjack1942


Users avatar

Posts
239
Registered at
2008-01-18 03:24:03
2013-10-11 16:32:10 - Re: Performance loss
Rod said @ 2013-10-11 14:59:10:
"You can only look for things that you suspect do exist."
No accounting for Serendipity, eh Rod?
;-)
Posted by
Rod


Users avatar

Posts
392
Registered at
2010-06-24 22:30:48
2013-10-11 18:25:24 - Re: Performance loss
Relying on Serendipity makes you a "Prince of Serendip". I am no 'prince'...science does not rely on just good luck. It needs observation, reasoning, and experimentation. Good luck may happen---then you win the lottery and don't have to worry about anything except greedy relatives.......
If it breaks, it's not strong enough--if it doesn't, it's too heavy.
Posted by
A2


Users avatar

Posts
347
Registered at
2009-10-26 00:39:42
2013-10-11 18:37:05 - Re: Performance loss
Initiative often succeeds where rationalization cannot.
None so blind
Posted by
WIN


Users avatar

Posts
357
Registered at
2009-07-09 23:32:07
2013-10-11 18:40:38 - Re: Performance loss
ciao ALL my friends ;)

just a little contribution from me on this subject :

I remember a few years ago a french soler discovered that jybing in several steps was reducing the perf loss, so I tried to see how it worked ......I did it once only and never again .

two main reasons for that :

1) by so doing the boat runs a longer course , and some of your perf loss saving is gone already, and the time at lower speed below VMG during the maneuver eats away another portion of the saving

2) ( and this is the main reason ) ....after the jybe your angle towards the next mark will no longer be the same and could be worst .......for longtime.

It is very true that also the contrary of item 2) may occur , but item 1) still stands .

IRL an offshore jybe is " smoothed" not so much for performance , but maily for smoothing the maneuver by the crew and keep the spi flying ......whilst , in-shore jybing around a mark smoothing the jybe could cost a number of positions .

Hope you all accept it as an opinion and contribution ..

ciaooooooooooooo ;) ;) ;)

Piero

PS : I did win quite a number of races in SOL , but never because I smoothed jybing or tacking to reduce perf loss..;)

Page: Previous 1 2 3 4 5 6 7 Next Last

Please login to post a reply.

Races

Next Race: 00d 00h 00m

Current Races:

Newport Bermuda Race 2026


The 636-mile Newport Bermuda Race is one of the oldest regularly scheduled ocean races, and with the Fastnet and the Sydney Hobart Race, it is one of the three great classic races of the yachting world. First raced in 1906, now in its 54th biennial, the Race can again also be participated in online. In real life, the race is open to entry in four different division – Double-Handed, St. David's Lighthouse, Gibbs Hill Lighthouse, and Finisterre Division – which in the past we have also offered online. This year, however, our online race will be all-in one-design in silky swift Club Swan 50 yachts, so that your results can count towards SOL’s SUPerBUDdy title, whilst hopefully still giving you a chance of overall line honours against the fastest yachts of the real-life Gibbs Hill Division, especially if you can find some forecast winds that don’t quite work out that way on the real water!
Race #2038
INFOby brainaid.de
Club Swan 50 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: SUPBUD - SYC
Race starts: Jun 19th 17:05 Registration Open!
▶ Flash
GO TO RACE

Bluefin Tuna - Mexico Gulf to North Sea 2026

Join us and follow the Bluefin Tuna, as they migrate from their spawning grounds in the Gulf of Mexico to their feeding grounds in the North Sea off the coast of Norway. This 4300 nm race is part of our Ocean Championship and the final race of OCQ2 2026, and also the second leg of our Migration series. We will be sailing in our Gunboat 90. Race #2035
INFO by brainaid.de
Gunboat 90 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: OCQ2 - MIG - OCCH - SYC
Race starts: Jun 08th 11:00 Registration Open!
▶ Flash
GO TO RACE

Thessaloniki to Port Said 2026

Welcome back to the Eastern Mediterranean for the fifth race of our Magical Mediterranean Series. Only marginally less unlikely to be ever raced in real life during SOL’s lifetime than our previous race from Tobruk to Iskenderun, this 710nm race takes us from Greece’s ancient northern port of Thessaloniki through the Aegean island maze, south east into the Levantine Sea to a finish in modern Port Said, in splendid Swan 65s!
Race #1977
INFO by brainaid.de
Swan 65 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: MED - SYC
RACE CLOSE: Wednesday,
June 17 at 2300 UTC.
Race starts: Jun 06th 15:00 Registration Closed

▶ Flash
GO TO RACE

TuziTekwini TIMED Race 2026

Sailonline is delighted to have been invited again 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 two weeks to test your skill and decision making after the race opens.
Race #2037
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 - SUPBUD - SYC
RACE CLOSE: Saturday,
13 June at 23:00 UTC
Race starts: May 31st 12:00 Registration Open!
▶ Flash
GO TO RACE

Go to race archive

SYC Ranking

  1. Sailonline Yacht Club Member WRmirekd
  2. Sailonline Yacht Club Member KaSToR
  3. Sailonline Yacht Club Member CriticalHippo
  4. Sailonline Yacht Club Member bonknhoot
  5. Sailonline Yacht Club Member rafa
  6. Sailonline Yacht Club Member Panpyc
  7. Sailonline Yacht Club Member HoratioPugwash
  8. Sailonline Yacht Club Member YANN
  9. Sailonline Yacht Club Member CollegeFund
  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