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
356
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:

SSANZ Round North Island Race 2026 - Leg 3

Leg Three of our Round North Island Series, in partnership with SSANZ, keeps the pressure on! From Cook Strait, the fleet turns north for a 187 nautical mile passage up the east coast to Napier. It may look like a quick overnighter, but shifting coastal winds and the ever-lively Cook Strait demand sharp focus. In our responsive Sun Fast 3600s, a proven short-handed racer and powerful downwind performer, tactical decisions and precise timing will make all the difference!

The start time for this race may change at short notice to align with the real race. The confirmed start date and time will be announced via an in-race “L” flag message — Please monitor race communications closely.
Race #2013
INFO by brainaid.de
Sun Fast 3600 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: RNI - SUPBUD - SYC
Race starts: Mar 08th 22:00 Registration Open!
▶ Flash
GO TO RACE

Dyer Dhow Derby 2026


Most winter weekends, SOLer wsguerin and his friends at the Mamaroneck Frostbite Association venture forth on Long Island Sound to race Dyer Dhows, originally designed as WWII tenders. Indestructible little boats, great comradeship and serious short sharp races of 10 to 20 minutes duration. Sailonline now invites you to experience the joys of the Dhow in winter, virtually, by way of a slightly longer 14nm race: from Mamaroneck to Execution Rocks, over to the Gong Buoy and back to Mamaroneck. And if the wind pipes up to 20kn and beyond, you'll find SOL's customized polar will plane, rather than nosedive!
Race #2017
INFO by brainaid.de
Dyer Dhow PARTICULARS
NAM_AWIP WX Updates:
0245 / 0845 / 1445 / 2045
Ranking: SPQ1 - SPCH - SYC
RACE CLOSE: Wednesday,
March 11 at 2300 UTC.
Race starts: Mar 07th 13:00 Registration Open!
▶ Flash
GO TO RACE

South China Sea Race 2026


Welcome all to the South China Sea and a virtual chase in Cookson 50’s of the Rolex South China Sea fleet, racing 650nm – as the local red-footed booby flies – from Hong Kong to Subic Bay on the southern tip of The Philippines’ Luzon Island. Chances are it will be a fast downwind ride, so see how you can keep up with the real-life fleet which we hope to be able to follow on our monitors.
Race #2016
INFOby brainaid.de
Cookson 50 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: SUPBUD - SYC
RACE CLOSE: Saturday,
March 14 at 2300 UTC.
Race starts: Mar 04th 03:20 Registration Open!
▶ Flash
GO TO RACE

SSANZ Round North Island Race 2026 - Leg 2

Leg Two of our Round North Island Series is where the real challenge begins. After Mangonui, our SOLers face a demanding 491nm passage around the top of the North Island and down the rugged west coast toward Cook Strait. Long miles, exposed waters, and relentless tactical choices will test every SOLer. In our powerful Sun Fast 3600s, a proven short-handed performer and true downwind flyer, endurance, timing, and smart routing will be key to success!

The start time for this race may change at short notice to align with the real race. The confirmed start date and time will be announced via an in-race “L” flag message — Please monitor race communications closely.
Race #2012
INFO by brainaid.de
Sun Fast 3600 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: RNI - SUPBUD - SYC
RACE CLOSE: Monday,
March 9 at 2300 UTC.
Race starts: Mar 02nd 21:00 Registration Closed
▶ 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 starts: Mar 02nd 11:00 Registration Open!
▶ Flash
GO TO RACE

San Diego to Puerto Vallarta 2026

Welcome to California! Established in 1953 this 1000-mile run from San Diego to Puerto Vallarta on the Mexican Riviera has become a tradition and online as well the tradition strengthens with this the fourth time Sailonline is making the race available to virtual sailors. Let's see how our virtual SC70s perform against the real fleet!
Race #2015
INFO by brainaid.de
Santa Cruz 70 Particulars
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: SUPBUD - SYC
RACE CLOSE: Friday,
March 13 at 2300 UTC.
Race starts: Feb 28th 20:00 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 vida
  4. Sailonline Yacht Club Member rafa
  5. Sailonline Yacht Club Member rumskib
  6. Sailonline Yacht Club Member CriticalHippo
  7. Sailonline Yacht Club Member Sax747
  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