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 » Performance diagrams

I'm curious about the VPP diagram for the 40 ft monohull. At high wind speeds, the lines sometimes cross each other, meaning that when the wind is increasing, the boat speed will decrease. I have not seen this in other VPP diagrams and it seems very unexpected to me. How do you explain this?
Lars Möller
Hometown: Karlskrona, Sweden
Hej, Well I am somewhat curious too... Sometimes things happen fast here... One can imagine situations where a higher wind speed results in lower boat speed. When beating this is often the case due to increased drag. When reaching this can also happen when e.g. a certain efficient sail cannot withstand the higher wind loads and thus cannot be used. So, such things can happen BUT: In this case I can agree that we have exaggerated the characteristics too much. Sorry.
...one of the guys behind the game...
Tks for your reply. However, an increased drag can only happen if the speed is increased. So, I'm afraid I'm still not convinced.
Compare for instance the VPP on this site:
http://www.shipman.dk/articles/?m0=6&m1=97
Lars Möller
Hometown: Karlskrona, Sweden
generally I agree that the polar lines shouldn't cross. But.. increased windage and heeling (causing increased rudder and increased displacement)can slow the boat down.
Hi. Fun discussion!. Lamo: one theoretically obtained polar does not make much as evidence unless you know much about the underlaying models. I can show you several polars with crossing curves. Secondly, I don´t think you read my last post thoroughly. Decreased speed does not have to be caused by increased drag. It might be caused by decreased thrust, as I was arguing the last time. I also agree with Pipedream that heal, waves etc complicates life. So, polar-lines might cross, nothing strange there. Ok?

...one of the guys behind the game...
Hi jakob

I guess you have studied polar diagrams a lot more than I. Still I like to understand what I see. For instance, the diagram for the VO70 makes sence as I see it. When reaching at TWA 130, the boat speed will always increase as the wind speed increases. Still the lines cross when close hauled, which you might expect because of increase wind and wave resistance. So far so good.

What I could not (and still cannot) understand is the feature in diagram for the 40 ft monohull at TWA 150 degr, where you have
10 m/s > 10 knots
12 m/s > abt 12,5 knots
14 m/s > abt 12,8 knots
18 m/s > abt 12,2 knots
22 m/s > abt 13,5 knots
In this case it's hard to imagine the behaviour of the 18 m/s line. Wind or wave resistance could hardly have this effect when reaching at 150 TWA.
Lars Möller
Hometown: Karlskrona, Sweden
Post hidden by jakob :
SNIP
Hi, First of all, as I admitted a couple of posts ago I agree that this polar is not perfect, It is hand-manipulated by us. The behavior you are referring to could still be a result of that no optimal sails are available for the 18m/s wind. So, principally, the characteristics are possible BUT I agree that in this particular instance the "bucket" is fairly unlikely. We will in the future try to come up with even more realistic polars. Thank you for communicating with us!
...one of the guys behind the game...

Please login to post a reply.

Races

Next Race: 00d 00h 00m


Current Races:

Kalamata to Alanya 2024


For the beginning of the ARCH competition's third quarter, we will sail our boat, SOTO 40, from Kalamata, Greece over the Aegean Sea always eastward to the race finish, 520nm away, in Alanya, Turkey.
Race #1824
INFO from brainaid.de
SOTO 40 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking:
ARQ3 - ARCH - SUPSOL - SYC
Race starts: Jul 22nd 17:00 Registration will open soon
▶ Flash
GO TO RACE

Kamchatsky to Tromsoe 2024

Just before the light failed entirely in Antarctica, Skip Novak managed to get his Pelagic 77 out of the ice and north up the Pacific to Kamchatsky. The sun is shining (24/7) and not a penguin to be seen, and Skip believes the Norh East Passage is ice-free (sufficiently) to attempt it, so all aboard for a c 4250nm voyage from east to west across the top of Siberia, Russia and Norway to Tromsoe!
Race #1779
INFOby brainaid.de
Pelagic 77 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: HLAT - SYC
Race starts: Jul 18th 19:00 Registration Open!
▶ Flash
GO TO RACE

Cowes to St Malo TIMED Race 2024

Organized by the Royal Ocean Racing Club since 1929, the Cowes to St Malo Race is a true RORC Classic. Starting from the Royal Yacht Squadron Line, Cowes, IOW, a magnificent spectacle can be watched from The Parade, Cowes. The Cowes to St Malo Race is part of the RORC Season’s Points Championship, the world’s largest offshore racing series. Dating back to 1906, the Cowes to St Malo Race precedes all of the world’s famous races including the Fastnet Race. This is a TIMEDrace, so you may RE-REGISTER HERE to try again, after finishing a run. You will have 13 days and 11 hours to show your skill and decision making after the race opens.
Race #1828
INFOby brainaid.de
TP-52 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking:
TRQ3 - TRCH - SUPSOL - SYC
RACE CLOSE: Saturday,
27 July at 23:00 UTC
Race starts: Jul 14th 12:00 Registration Open!

▶ Flash
GO TO RACE

Lake Ontario 300 Challenge 2024

Lake Ontario Offshore Racing (LOOR) welcomes Sailonline to a second race of their annual series, this time as hosts of the virtual 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 on SOL, this 300 and the Susan Hood raced back in May; so let the competition be fierce!
Race #1805
INFOby brainaid.de
First 36.7 PARTICULARS
NAM_AWIP WX Updates:
0245 / 0845 / 1445 / 2045
Ranking: LOOR - SYC
Race starts: Jul 13th 15:10 Registration Open!

▶ Flash
GO TO RACE

SSANZ Triple Series 2024 - Race 1


Welcome once again to our online buddied Short-handed Sailing Association of New Zealand brilliant long-standing SSANZ Triple Series for two-handed yachts on the waters of the Hauraki Gulf, sponsored this year by Lewmar Marine. Commencing with a c 46nm quick dash out to Motuora Island via The Haystack and home, we will as always compete in virtual Young88s, against the real-life fleet of the members of the ever-Young 88 Association!!
Race #1823
INFO by brainaid.de
Young 88 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: SSANZ - SYC
Race starts: Jul 12th 21:15 Registration Closed
▶ Flash
GO TO RACE

Tall Ships Races 2024 - Tallinn to Turku


Welcome to the second of three virtual Tall Ships Races on the Baltic Sea which are concurrently being organized in-real-life Sail Training International . This second race is from Tallinn, Estonia to Turku, Finland; circa 150nm in Sailonline’s stately Full Rigger.
NOTE: Starts and Finishes in tall ships racing are always offshore to avoid conflict with shipping and shipping lanes.
Race #1812
INFO by brainaid.de
Full Rigger PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: TS - SYC
RACE CLOSE: Friday,
July 19 at 2300 UTC.
Race starts: Jul 11th 14:00 Registration Closed
▶ Flash
GO TO RACE

Southampton to Punta del Este 2024

Sailonline is delighted to offer our sailors a 'reversed' Atlantic ocean race. As the RTW championship Atlantic part takes a detour to the Bahamas, we will offer you a reversed course as we will not do the 'usual' leg this year either. It is the July edition of this year's Ocean Championship. Our boat is the OD_65v3.
PRIZE: SMPF
Race# 1820
INFO from brainaid.de
OD65 PARTICULARS
WX updates:
0430 / 1030 / 1630 / 2230
Ranking: OCQ3 - OCCH - SUPSOL - SYC
Race starts: Jul 01st 11:00 Registration Closed
▶ Flash
GO TO RACE

Go to race archive

SYC Ranking

  1. Sailonline Yacht Club Member WRmirekd
  2. Sailonline Yacht Club Member FreyjaUSA
  3. Sailonline Yacht Club Member CriticalHippo
  4. Sailonline Yacht Club Member Vida_Maldita
  5. Sailonline Yacht Club Member rafa
  6. Sailonline Yacht Club Member TarassBoulba
  7. Sailonline Yacht Club Member Flamingo
  8. Sailonline Yacht Club Member CollegeFund
  9. Sailonline Yacht Club Member Sax747
  10. Sailonline Yacht Club Member bonknhoot

View full list

Series

Mobile Client

SYC members have the benefit of access to our mobile/lightweight web client!

The mobile client