Login
Support Sailonline
If you haven't already  join the SAILONLINE YACHT CLUB!
Please also consider making a donation  all amounts are greatly appreciated!
Page: First Previous 2 3 4 5 6 7 8 Next Last
Posted by javakeda 

A2R: The maxBtSpd for 17kts is about 13kt, so not really close to the 16+kts needed based on the BtSpd rule alone.
I think the TreffTeam site, noted in my prior post, really tells us a lot. I would love to know the complete history of that site. I suspect that it was developed to support both virtual and real life racing. VR is a likely virtual venue. Note the heading "Ocean Virtuel" above the 3Dgraphics that show colorcoded sail preferences. I really have to admire the work that went into this site. So, why the switch to sailonline? I don't want to speculate. I am just glad it happened. Meanwhile, here is an alternative hypothesis for the PERF change: The BtSpd rule applies, but there is an additional penalty for changes in COG that exceed Xdegrees  and we have to figure out what X is. Maybe something like: PERF=(100BtSpd/2)*deltaDEGREES/XDEGREES If it looked like that, I'd bet on XDEGREES=90 (pi/2 in radians) coupled with a test on the sign of the TWA. If the sign changes, the deltaDEGREES is assumed to be at least 90. But all that is just a priori guesswork. I should be able to test both hypotheses in the same data gathering series. Back to the stopwatch. 

Posted by A2 

Example cited is consistent with the formula
(I should have done the math before commenting)  Last Edited by A2R at 20131015 11:24:27  None so blind 

Posted by kroppyer 

Ok, so this is the image, and raw data from tonight's practice race. I think we can conclude that performance recovery is linear, or at least close to linear (without steps).
If anyone wants to have the PHP script I used, ask me. You'll need to know how to run PHP scripts, and how to install pear's System Daemon1.0.0 

Posted by Rod 

May I suggest, Kroppyer, in all due humility etc etc ...We are attempting here to clarify and to simplify the perf loss and recovery phenomenon for the benefit of those among us (such as myself) who either are many years since their last mathematics course or have only a small knowledge of math. If processes or notations, that are not simplified or clarified, are introduced in this discussion, it just further adds mystification to a procedure that is already somewhat obscure to many SOLers.
p.s. An example was the introduction of 'radians' instead of 'degrees' into the discussion. I know radians etc, but their extra convenience in calculations is not something I understand immediately. I can visualize the Captain, in an emergency, giving the order, "0.356 Radians of sinister wheel on!" and being answered by "HUH?" i.e. it is not maritime terminology......  Last Edited by Rod at 20131014 21:15:34  If it breaks, it's not strong enoughif it doesn't, it's too heavy. 

Posted by javakeda 

And may I suggest, Rod, with all due humility that we watch and learn from Kroppyer.
Note that his data logging program is far more accurate than hand logging from the SOL client. It establishes, beyond a doubt in my mind, that the PERF recovery rate is linear and constant. Well, done, indeed! As for the math terms in use, nothing mentioned in this thread so far goes beyond what I learned in 10th grade  in 1954. When I became interested in routing, I realized I needed a refresher course or two. I took a number of courses at Khan Academy. Here is the url: https://www.khanacademy.org/ The courses are free, and bite sized. I recommend this site to anyone who wants to polish their basic math skills. As for using the term 'radians'...I offer no apologies. If you want to use a spreadsheet to calculate VMG and such, you need to be able to use the RADIANS function to translate from degrees to radians. This is not an obscure term. 

Posted by kroppyer 

Rod, thanks for the feedback on my way of communicating in this thread. I am trying to find the formulas behind the performance loss and recovery model. When I found a model that is close enough to the one SOL uses, I will describe it in a way that most people will understand it, even if they're not too good with maths, I want to put this performance model in the calculator of spinnacer. While I'm trying to discover these formulas I'm not really focussing on making it understandable to all. I'm merely sharing my findings and thoughts for those interested. I hope everyone will do the same. All contributions of other people are welcome, the more data/thoughts/discoveries, the better. I will try describe and explain a little more, but I'm still trying to find the actual formulas and then explain them, instead of explaining how I'm trying to find them.
I made a new version of the PHP script, polling every 5 seconds. It also uses two models which try to predict the performance loss. So we can compare the actual performance loss matches with the model and see if it matches. I discovered that recovery is not perfectly linear: recovery per minute is 9/boatspeed%, but boatspeed is increasing as performance is increasing, so its not a constant rate of recovery. In the image, m1_eff is using the assumption that the boatspeed used to calculate the rate of recovery is the actual boatspeed, m2_eff is using the assumption that the rate of recovery is based on the boatspeed when perf would be 100%. I included the raw data, but it's cut off because I has some internet problems. So I'll try again, with some more different manoeuvres, another time. The raw data is a csv file, which can be opened with excel, or another spreadsheet program, but also with a text editor. I included the angles in degrees in the file. I'm looking forward to the day captains order their helmsman to steer ".2 tau" (.2 being in base 12, and tau being 2*pi), and pilotes are "requesting takeoff from runway .9 tau" EDIT: the graph (image) has a wrong scale on the xaxis (horizontal), the numbers are seconds, not minutes.  Last Edited by kroppyer at 20131014 23:39:32  

Posted by javakeda 

Kroppyer:
I remain in awe, and am watching and learning. I think the last time I programmed in PHP the version level was 3something. I'd love to update my version  just to understand what you are doing. Again, the last time I programmed and ran PHP I used a standalone UNIX server. The application was paired with a MySQL database. I was helping a nonprofit group manage their event attendance. This was volunteer work. Not sure what I would need to run your script. I would hope that I could run it in a standalone environment [UNIX, or whatever]. Your knowledge here is leagues ahead of mine. Would love to discuss this offline. Not sure how that happens. netwrangler@yahoo.com is an email path that might work. Regards, Javakeda Bob 

Posted by A2 

Posted by
javakeda 20131014 17:17:35 Sail Management "Sailing my SOLTP52 in ~17kts TWS earlier today, I reached off from a TWA of 36 to a TWA of 153. I was greeted with an initial PERF hit down to 91.83%" =========================== 117 degrees equals 2.042035 radians divided by 25 equals 0.0816814 Efficiency of 91.832%  Last Edited by A2R at 20131015 11:52:55  None so blind 

Posted by A2 

For every Degree of course change,
that does not induce a Tack or Gybe, there is a .06981317% Performance Loss. None so blind 

Posted by sol 

oops, wrong account
 kroppyer  Last Edited by sol at 20131015 12:48:19  
Page: First Previous 2 3 4 5 6 7 8 Next Last
Please login to post a reply.Races
Next Race: 00d 00h 00m
Current Races:
Round Britain and Ireland 2022
We invite you to participate in the 1780 nm race according to the clockwise movement around Ireland, Scotland, Shetland Islands and England. We will have four waters: the North Atlantic Ocean, the Celtic Sea, the North Sea, La Manche Channel. Each of them has its own specific navigation conditions but we will not exchange them here. Watch out for cyclones forming in the vicinity of Iceland and wandering in the south  east. The wind speed at this time of year can reach up to 40 kts and even more. Let's hope that sailing experience and our Sunfast3600 will safely lead us to the finish line.
Race #1625
INFO by brainaid.de
Sun Fast 3600 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: SYC
Race starts: Oct 01st 18:00
Registration Open!
Tour Down Under 2022
It will be 694nm of killing racing on an amazing route created by SOL'er AGage. In the chat of the first edition of this race, Tyger wrote "Only an Aussie (and a crazy one) with intimate knowledge of these waters could have come up with such a racecourse". Well maybe AGage was a bit crazy, but he was also a genius when he made it, inspired by the great cycling race "Tour Down Under". Instead of bikes we will use fast 60ft Trimarans. So rest well and prepare large amounts of coffee. You will have at least two days without sleep. ðŸ˜Š
Race #1595
INFO by brainaid.de
60ft Trimaran PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking:
ARQ3  ARCH  SUPSOL  SYC
Race starts: Sep 25th 02:00
Registration Open!
Hong Kong to Auckland 2022
It's time to test your ocean racing skills in a variety of weathers as we head the 6400 NM between Hong Kong and Auckland in a fast Super Maxi 100. We'll be heading from a northern summer to a southern winter so keep plenty of cold weather gear and warm rum on board!
PRIZE: SMPF
Race #1597
INFOby brainaid.de
Super Maxi 100 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking:
OCQ3OCCHSUPSOLSYC
RACE CLOSE: Wednesday,
September 28 at 2300 UTC.
Race starts: Sep 01st 04:00
Registration Closed
SYC Ranking
Series
 SYC ranking
 2023 DN
 2022 TRQ4
 2022 TRQ3
 2022 TRQ2
 2022 TRQ1
 2022 TRCH
 2022 Tall Ships
 2022 SUPerSOLer
 2022 SSANZ
 2022 SSA
 2022 SPRQ4
 2022 SPRQ3
 2022 SPRQ2
 2022 SPRQ1
 2022 SPRCH
 2022 SHE
 2022 OCQ4
 2022 OCQ3
 2022 OCQ2
 2022 OCQ1
 2022 OCCH
 2022 NTR
 2022 LOOR
 2022 CTR
 2022 ARQ4
 2022 ARQ3
 2022 ARQ2
 2022 ARQ1
 2022 ARCH
 2021 TRQ4
 2021 TRQ3
 2021 TRQ2
 2021 TRQ1
 2021 TRCH
 2021 TD
 2021 Tall Ships
 2021 SYCQ4
 2021 SYCQ3
 2021 SYCQ2
 2021 SYCQ1
 2021 SYCCH
 2021 SUPerSOLer
 2021 SSANZ
 2021 SPRQ4
 2021 SPRQ3
 2021 SPRQ2
 2021 SPRQ1
 2021 SPRCH
 2021 Shetland
 2021 PAC6
 2021 OCQ4
 2021 OCQ3
 2021 OCQ2
 2021 OCQ1
 2021 OCCH
 2021 ESRW
 2020 TSE
 2020 TSA
 2020 TRQ4
 2020 TRQ4
 2020 TRQ3
 2020 TRQ2
 2020 TRQ1
 2020 TRCH
 2020 Tasman Double
 2020 SYCQ4
 2020 SYCQ3
 2020 SYCQ2
 2020 SYCQ1
 2020 SYCCH
 2020 SUPerSOLer
 2020 SSANZ
 2020 SRQ4
 2020 SRQ3
 2020 SRQ2
 2020 SRQ1
 2020 SPRCH
 2020 Shetland
 2020 RTW
 2020 RNI
 2020 Odyssey
 2020 OCQ4
 2020 OCQ3
 2020 OCQ2
 2020 OCQ1
 2020 OCCH
 2020 A3
 2019 TRQ4
 2019 TRQ3
 2019 TRQ2
 2019 TRQ1
 2019 TRCH
 2019 Tasman Double
 2019 Tall Ships
 2019 SYCQ4
 2019 SYCQ3
 2019 SYCQ2
 2019 SYCQ1
 2019 SYCCH
 2019 SUPerSOLer
 2019 SSANZ
 2019 SRQ4
 2019 SRQ3
 2019 SRQ2
 2019 SRQ1
 2019 SPRCH
 2019 Shetland
 2019 Round New Zealand
 2019 OCQ4
 2019 OCQ3
 2019 OCQ2
 2019 OCQ1
 2019 OCCH
 2018 TRQ4
 2018 TRQ3
 2018 TRQ2
 2018 TRQ1
 2018 TRCH
 2018 Tasman Double
 2018 Tall Ships
 2018 SUPSOL
 2018 SSANZ Triple
 2018 SRQ4
 2018 SRQ3
 2018 SRQ2
 2018 SRQ1
 2018 SPRCH
 2018 Shetland
 2018 Shackleton Challenge
 2018 OCQ4
 2018 OCQ3
 2018 OCQ2
 2018 OCQ1
 2018 OCCH
 2018 40CH
 2017 TS RDV
 2017 TRQ4
 2017 TRQ3
 2017 TRQ2
 2017 TRQ1
 2017 TRCH
 2017 Tasman Double
 2017 Tall Ships
 2017 SWR
 2017 SUPSOL
 2017 SSANZ Triple
 2017 SSANZ RNI
 2017 SPRR3
 2017 SPRR2
 2017 SPRR1
 2017 SPRCH
 2017 Red Dot
 2017 OCQ4
 2017 OCQ3
 2017 OCQ2
 2017 OCQ1
 2017 OCCH
 2017 40CQ3&4
 2017 40CQ1&2
 2016 TRQ4
 2016 TRQ3
 2016 TRQ2
 2016 TRQ1
 2016 TRCH
 2016 Tasman Double
 2016 Tall Ships
 2016 SUPSOL
 2016 SSANZ Triple
 2016 SRQ4
 2016 SRQ3
 2016 SRQ2
 2016 SRQ1
 2016 SPRCH
 2016 RTWR
 2016 OCQ4
 2016 OCQ3
 2016 OCQ2
 2016 OCQ1
 2016 OCCH
 2016 Corporate Open Gold
 2016 A3
 2015 TRQ4
 2015 TRQ3
 2015 TRQ2
 2015 TRQ1
 2015 TRCH
 2015 Tasman Double
 2015 Tall Ships
 2015 SYQ4
 2015 SYQ3
 2015 SYQ2
 2015 SYQ1
 2015 SYCCH
 2015 SUPSOL
 2015 SSANZ Triple
 2015 SRQ4
 2015 SRQ3
 2015 SRQ2
 2015 SRQ1
 2015 SPRCH
 2015 OCQ4
 2015 OCQ3
 2015 OCQ2
 2015 OCQ1
 2015 OCCH
 2015 Aegean Rally
 2014 Timed Races Championship
 2014 Tasman Double
 2014 Tall Ships
 2014 SYC Championship
 2014 SSANZ Trio
 2014 SSANZ RNI
 2014 Sprints Championship
 2014 Scandinavian Tour
 2014 Round The World Race
 2014 Ocean Championship
 20142015 Sailonline World Race
 2013 Tall Ships
 2013 SYC Championship
 2013 SSANZ B&G Simrad
 2013 Capt Anderson
 2012 W Australia Regatta
 2012 Tall Ships
 2012 SSANZ B&G Simrad
 2012 RNZ Two Handed
 2012 Global Challenge
 2012 Ecker Cup
 2012 Black Sea
 2012 A3
 2011 Vancouver Island
 2011 Tasman Double
 2011 SSANZ B&G Simrad
 2011 SOL Global Challenge
 2011 SJORA Series
 2011 Scandinavian Tour
 2011 Round North Island
 2011 Asian Sprints
 20112012 SOL World Race
 2010 Tasman Double
 2010 Ouzo Rally
 2010 Iberian Tour
 2010 Auckland Regional
 2009 French SOLo
 2009 Bosphore  Bretagne
 2008 SYCC
 2008 2013 SYC Week Race Championship
 2008 2013 SYC WeekEnd Race Championship
 2008 2013 SYC Ocean Race Championship
 20082009 Sailonline Ocean Race
Mobile Client
SYC members have the benefit of access to our mobile/lightweight web client!