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

Posted by
lamo


Users avatar

Posts
8
Registered at
2008-01-30 16:25:11
2008-02-03 16:32:24 - 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
Posted by
jakob


Users avatar

Posts
364
Registered at
2007-09-04 10:05:30
2008-02-03 16:49:09 - Re: Performance diagrams
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...
Posted by
lamo


Users avatar

Posts
8
Registered at
2008-01-30 16:25:11
2008-02-03 17:13:02 - Re: Performance diagrams
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
Posted by
pipedream


Users avatar

Posts
11
Registered at
2008-02-06 09:19:15
2008-02-10 12:26:02 - Re: Performance diagrams
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.
Posted by
jakob


Users avatar

Posts
364
Registered at
2007-09-04 10:05:30
2008-02-10 15:15:14 - Re: Performance diagrams
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...
Posted by
lamo


Users avatar

Posts
8
Registered at
2008-01-30 16:25:11
2008-02-11 22:46:12 - Re: Performance diagrams
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
Posted by
mytest


Users avatar

Posts
2
Registered at
2007-12-28 22:45:33
2008-02-12 06:39:43 - Re: Performance diagrams
Post hidden by jakob :
SNIP
Posted by
jakob


Users avatar

Posts
364
Registered at
2007-09-04 10:05:30
2008-02-12 08:08:17 - Re: Performance diagrams
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:

PIC Coastal Classic Yacht Race 2026

Kia Ora, SOLers! Welcome back to Auckland for the 2026 PIC Coastal Classic! In partnership with the New Zealand Multihull Yacht Club, Sailonline is thrilled to bring you this iconic 118nm legendary sprint to Russell.

Expect the unexpected on this tricky course up the North Island's East Coast—from adrenaline-fueled spinnaker rides to nail-biting pre-dawn lulls. This year, we take on the elements in the highly popular Seacart 30. Designed by Marc Lombard, this nimble trimaran features a challenging polar that rewards pure tactical precision.

Chart your course, conquer the coastal currents, and race for ultimate bragging rights! Upon crossing the finish line in scenic Russell, the traditional reward of bacon butties and rum awaits!
Race #2067
INFO by brainaid.de
Seacart 30 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: SYC - SUPBUD - RED
Race starts: Oct 23rd 22:30 Registration will open soon
▶ Flash
GO TO RACE

Mad Max by Balloon 2026 - Across the Outback


Mad Max Rockatansky doesn’t get to go in a balloon in any of the Legends of the Wasteland, and the Wasteland is not necessarily the Outback of Australia, but Mel Gibson and film director George Miller indubitably are… of Australia, and ballooning as reconnaissance is a main feature of the Mad Max spin-off video game, so here goes: 1500nm in a balloon from somewhere on the edge of the Outback, Goondiwindi, to cross a finish line at Fitzroy Crossing, somewhere on the edge of the Outback!
Race #1974
INFOby brainaid.de
SOL Balloon PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: BOL - SYC
Race starts: Oct 14th 13:00 Registration Closed
▶ Flash
GO TO RACE

Valdes Peninsula TIMED Race 2026

October finds us on the Argentina coast for the Valdes Peninsula race. A UNESCO World Heritage Site the peninsula is a breeding ground for southern right whales. Sail the luxurious blue water Delphia 47 around a 160 nm course in an attempt to turn in the fastest time.
This is 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 #2066
INFOby brainaid.de
PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking:
TRQ4 - TRCH - SYC
RACE CLOSE: Saturday,
24 October at 23:00 UTC
Race starts: Oct 11th 12:00 Registration Open!
▶ Flash
GO TO RACE

Arctic Tern - Greenland to Antarctica 2025

Welcome to the fifth leg of our MIG series. Now it's time to race the Arctic Terns, on their migration from Greenland to Antarctica, 8300 NM. This is also part of our monthly Ocean Championship, and as such the first race of OCQ4 2026. This race will be sailed in our Maxi Trimaran. Race #2061
INFO by brainaid.de
Maxi Trimaran PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230 Ranking:
OCQ4 - OCCH - SYC - MIG
Race starts: Oct 05th 11:00 Registration Closed
▶ Flash
GO TO RACE

Cross the Convergence 2026 - Masirah to Chagos


Having crossed, re-crossed and re-re-crossed the Convergence Zones of the Pacific and the Atlantic, we now face our second crossing of the Convergence Zone of the World’s third great equator-spanning sea, the Indian Ocean, taking us from the channel between Masirah Island and the Oman mainland to the Chagos Archipelago. It’s 1900nm and we’ll be sailing our very fine Archer 78, and won’t mention that both locations (of departure and arrival) are heavily militarized and the why’s and what next’s concerning that – mindful as always of SOL Netiquette.
Race #1988
INFOby brainaid.de
Archer 78PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: CCZ - SYC
RACE CLOSE: Tuesday,
October 20 at 2300 UTC.
Race starts: Oct 02nd 18:00 Registration Closed
▶ Flash
GO TO RACE

Go to race archive

SYC Ranking

  1. Sailonline Yacht Club Member KaSToR
  2. Sailonline Yacht Club Member CriticalHippo
  3. Sailonline Yacht Club Member WRmirekd
  4. Sailonline Yacht Club Member rafa
  5. Sailonline Yacht Club Member rumskib
  6. Sailonline Yacht Club Member Panpyc
  7. Sailonline Yacht Club Member cdhinman
  8. Sailonline Yacht Club Member BRENTGRAY
  9. Sailonline Yacht Club Member rthinman
  10. Sailonline Yacht Club Member ita10267

View full list

Series

Mobile Client

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

The mobile client