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: Previous 1 2 3 4 5 6 7 Next Last
Posted by Rod 

I have been exploring the rate of recovery of "perf" after a gybe of 270 degrees at a speed of 2526 knots. The rate of recovery is linear, but has two components. It required 20 minutes to recover, but for the first 16 minutes the rate of recovery was 0.4% per minute. For the last 4min, the rate was0.74% / minute.
After a gybe of 180deg, at the same speed, it required 23 minute, at a rate of 0.52% per min for the first 15.5 min, and then a rate of 0.90% / min for the last 7 minutes. I can see no reason for either the greater loss for the lesser turn, or for the changes in recovery rate that were observed. I will continue to collect data. As Alice said, "This is getting curiouser and curiouser!" p.s. I think it was Alice (of Wonderland fame,) but I'm not certain....  Last Edited by Rod at 20131011 21:48:54  If it breaks, it's not strong enoughif it doesn't, it's too heavy. 

Posted by kroppyer 

This peace of code does not include performance recovery.
As far as I can tell from this code, it doesn't matter if you gybe from twa=155 to twa=155, or from twa=175 to twa=175. performance is in boat gybe half you boat speed. What is possible (what I believe hmm did) is to change course to twa=179 (slow) then gybe to best VMG (low performance loss because low boat speed. With the tall ships you might be able to tack with almost no performance loss: you're sailing with twa=70, change course to twa=(about)50, so that you boat speed is (almost) 0. Then tack to twa=70 (no extra performance loss). I'm not sure whether 10 seconds with speed=0 is better than a little more performance loss. This makes me think... tall ships can sail backwards.. tacking when you're speed is negative should increase performance according to this code. In the most extreme case you could sail with 0.373 kts backwards, tack an have a performance of 100.19%. It's quite possible that there's something in the performance recovery code that prevents the performance from exceeding 100%. EDIT: Currently trying these things.. I'm wrong on at least one point: it the boatspeed *after* the tack/gybe that determines performance loss. EDIT: There are still weird things going on. In the tall ships race, there's not enough wind to go "fast" backwards. I was not able to get performance above 100% It might be possible to speed up de performance recovery (with the negative speed trick), but I can't measure that now (I can only do a 0.02% increment). I noticed something weird with speeds <= 0. Somehow, if you tack, and your speed after the tack is smaller of equal to 0, your performance is 100% immediately. When you change course (don't tack or gybe) to an angle with a boatspeed smaller or equal to 0, your performance recovers very fast. Has boatspeed something to do with performance recovery? That would explain why fast boats have slow recovery.  It's not that one of these things would make you any faster, but while discovering how SOL works, we might find some things that do make you faster. These performance things might be very interesting for practice racers (like me)  Last Edited by kroppyer at 20131011 22:10:37   Last Edited by kroppyer at 20131011 22:27:13  

Posted by A2 

Ok so if its the speed after the G/T then could the flat turn gybe that hmm did at Digby be 1st to just do a change sign at 179.99 then go to VMG ? None so blind 

Posted by kroppyer 

Yes, at this point I think something like this happened:
twa=145 twa=179.99 (speed: 17.3 kts, perf.: 91.35%) twa=145 (no additional perf. loss because perf<93%) ===(edit)=== Let me add a "translation" for those not familiar with programming. Now e is a percentage (0100%), boatspeed is in knots, dTWA is positive difference in course, in degrees (I believe dTWA was in radians in the original code).  If (tack or gybe (twa changes sign)) then e = 100  boatspeed/2 else e = 100  dTWA*180/(25*PI) end perf = perf*(e/100).  There is something with the recovery though, sometimes the performance loss is very low or not even noticeable. I think this is because recovery is very fast when boat speed is low.  Last Edited by kroppyer at 20131012 08:09:20   Last Edited by kroppyer at 20131012 08:11:23  

Posted by Rod 

What is " PI "???? If it breaks, it's not strong enoughif it doesn't, it's too heavy. 

Posted by hmm 

PI = 3.141592...
Probably that is because dTWA is in radians. 

Posted by Rod 

Complicateder and complicateder"Radians"? If it breaks, it's not strong enoughif it doesn't, it's too heavy. 

Posted by A2 

I found this graphic that I snagged in the past that was posted here in the Forum. Unfortunately I don't know who provided it but it does relate to Boat Speed recovery.
The url where it was linked from is no longer valid but this is the defunct location. http://farm3.staticflicker.com (space added) /2357/2063504228_33f768fe40.jpg By looking at the graph axis labels 'e' stands for efficiency in the formulas that are under discussion. This is not definitive but it is a start None so blind 

Posted by hmm 

Rod, you know you have a computer in front of you which has the ability for search for information?
Whether you like it or not, simulating the performance requires mathematics. And if you want to understand that, you should be aware of some basic mathematical terms like "pi" and "radian". The answer is the first hit google gives you for "radians". 

Posted by Rod 

I know Pi and radians, but is it necessary for the calculation? It's a long time since I did a lot of math, and I'm sure many SOLers don't even remember as little as I do about how to manipulate radians in an equation. I will persist...... If it breaks, it's not strong enoughif it doesn't, it's too heavy. 
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:
Melbourne to Hong Kong
After celebrating Christmas and New Year it is time for the second run in this year's Ocean Race Championship. After leaving Melbourne on this (about) 5.500 NM course, we will leave the Solomon Islands, Papua New Guinea and the Philippines, all to port. And remember, once again we'll have to choose the best way to cross the Doldrums
PRIZE: SMPF
Race #1658
INFOfrom brainaid.de
OD65v3 Particulars
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking:
OCQ1OCCHSUPSOLSYC
Race starts: Feb 04th 05:00
Registration Open!
Buenos Aires to Rio 2023
This year's second ARCH series race will run from Buenos Aires, Argentina to Rio de Janeiro, Brazil on a route designed by SOLer Vida_Maldita (under his former alias of zero) in 2013. This is a replica of a classic triennial race of 1200nm, first run in 1947. More information about this IRL race can be found here.
So, Bemvindo/Bienvenidos in this coastal classic and prepare your 90ft Monohulls well.
Race #1662
INFO by brainaid.de
90ft Monohull PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking:
ARQ1  ARCH  SUPSOL  SYC
Race starts: Feb 01st 18:00
Registration Open!
Up Helly Aa 2023
AOI!!! The cry should soon be ringing out in the streets of Lerwick as the Guizer Jarl and his crew, along with the other teams in the Up Helly Aa parade complete their preparations for the biggest fire festival in Europe. As is Sailonline's tradition, we shall be racing the 383nm from Aberdeen to Lerwick to (virtually) take part in the Up Helly Aa festivities there which take place for the first time since 2020 on Tuesday, 31 January. SAILING NOTE: Gruney may be approached from any direction but must be passed for rounding purposes as indicated on the chart.
Race #1660
INFO by brainaid.de
Elan 410 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: SYC
RACE CLOSE: Friday,
3 February at 2300 UTC
Race starts: Jan 28th 11:00
Registration Open!
SYC Ranking
Series
 SYC ranking
 2023 TRQ4
 2023 TRQ3
 2023 TRQ2
 2023 TRQ1
 2023 TRCH
 2023 SVS
 2023 SUPerSOLer
 2023 SPRQ4
 2023 SPRQ3
 2023 SPRQ2
 2023 SPRQ1
 2023 SPRCH
 2023 RNI
 2023 OCQ4
 2023 OCQ3
 2023 OCQ2
 2023 OCQ1
 2023 OCCH
 2023 DN
 2023 ARQ4
 2023 ARQ3
 2023 ARQ2
 2023 ARQ1
 2023 ARCH
 2022 TRQ4
 2022 TRQ3
 2022 TRQ2
 2022 TRQ1
 2022 TRCH
 2022 TD
 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!