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Magnum
26-01-11, 22:24
Does anyone use this data in their day to day sailing? If so how?

jimi
26-01-11, 22:25
to avoid lond distance swimming bears

Angele
26-01-11, 22:48
The racing community does. It shows the theoretical maximum speed of their boat at a particular wind angle and speed. I think they constantly tweak things until they are within a whisker of what the boat is capable of achieving.


The rest of us just open another beer.;)

sarabande
26-01-11, 22:49
sail selection for speed and angle of wind; optimising vmg, weather routing (very important if out for more than 24 hours), passage planning.


You should be getting a full polar with the boat from the designer's velocity prediction program; if you don't, it's relatively easy to make up the data table from real life into a spreadsheet, and then convert it to a graphic. Perhaps your wind/speed electronics incorporates a data logging system which will make that much easier.

EDIT

Maxsea is a nav software package which does clever things with wind / boatspeed data.

http://www.maxsea.fr/timezero/Products/Documentation/Factsheets/tabid/149/id/932/language/en-US/Default.aspx. There are other apps around, too.

tcm
26-01-11, 23:06
yeah, the polar curves are specially designed to pi$$ you off, describing how fast your boat would go if you had no fuel or water or gear or antifoul PLUS you were sh!t hot at sailing and didn't have to pay if the boat breaks. But anyway, no, to answer the question, i have never looked at the polar curves during the sailinfg eg "quick, go get the polar curves willyer?"

sarabande
26-01-11, 23:15
I am convinced that boats go faster if you use the polar curve sheet as a fan....

sarabande
26-01-11, 23:19
just discovered that B&G produce the Deckman program which just about covers most decent tech tools for sailing more efficiently. It includes a polar generator.

http://www.bandg.com/Products/Deckman-Tactical-Software/More-about-Deckman/

Magnum
26-01-11, 23:46
just discovered that B&G produce the Deckman program which just about covers most decent tech tools for sailing more efficiently. It includes a polar generator.

http://www.bandg.com/Products/Deckman-Tactical-Software/More-about-Deckman/
We have that on our new boat. Not used it yet though!

sarabande
26-01-11, 23:58
Ah, should have thought you would be ahead of the game !

Polars are useful , as well as fun, and extend your 'feel' for selecting the right sail combinations, and for how the boat is moving.

snowleopard
27-01-11, 08:42
One particular area where polars can be very useful is when running in multis and lightweight flyers, especially with asymmetrics. If the polar shows a 'dent' at the 180° position, it is more efficient to tack downwind as the extra speed obtained from going onto a broad reach is more than the loss from covering extra distance.

As polars are almost always theoretical and my efforts to produce one experimentally failed because of wind fluctuations, I couldn't deduce the optimum angle from the plot. When I tried it out there was a marked increase in speed by heading off the direct downwind line but the VMG dropped. I can now head straight for my destination in a leisurely fashion with no feelings of guilt!

This boat goes faster tacking downwind at 30° off the direct line:

http://www.omerwingsail.com/lib/2016869.gif

This boat is best sailed direct downwind:

http://www.sanjuan28.org/images/Misc/Polar_SJ28a.jpg

Also you can see that in the first polar, though the boat will make progress at 20°-30°, the best upwind VMG will be obtained at 40°

Bilgediver
27-01-11, 12:19
just discovered that B&G produce the Deckman program which just about covers most decent tech tools for sailing more efficiently. It includes a polar generator.

http://www.bandg.com/Products/Deckman-Tactical-Software/More-about-Deckman/

I think this was one of the least used features of the Phillips AP8 GPS. it would take the NMEA inputs from the instruments and produce a diagram.

One mate with a Westerly Storm used this to perfect his tweeking...Must have worked as he won races but the Saturday tweeking could be hard work and often gave me Tiller Elbow. I am a wheel man : The Dolphins thought it was fun and often chased us.

davidej
27-01-11, 12:33
I have googled unsucessfully to get a polar for my boat -probably more for acedemic interest than as a true sailing tool.

It is a bene 361 any suggestions?

snowleopard
27-01-11, 13:50
For most modern boats you should be able to get polars, stability curves etc from the manufacturers.

Juniperskip
27-01-11, 17:26
For racing or tweaking fun you need to translate your polars into a chart of target speeds for true wind direction/speed.

The Navman software will help with this but a simple chart with numbers(digital!!) is the usual way. For racing I have a separate one for sail selection ie foresail or A-sail choice either pre-start or at a mark rounding....

sarabande
27-01-11, 18:13
Juniper - can you clarify that with regard to VMC and VMG pls ?

)Not being whingy; want to learn)

PembrokeshirePromise
27-01-11, 18:19
<<i have never looked at the polar curves during the sailinfg eg "quick, go get the polar curves willyer?">>

That cos they don't do them for cling film round the guard rails ... ;-)

dt4134
27-01-11, 18:24
Juniper - can you clarify that with regard to VMC and VMG pls ?

)Not being whingy; want to learn)

For racing you have a target boat speed against which you compare your actual boatspeed. It is one bit of information that helps you decide whether you're sailing well enough.

For example, close-hauled you should know what boat speed and what angle you should be getting to the wind at various windspeeds.

Similarly downwind the polars will guide you on the correct 'tacking' angles and expected boatspeed.

They'll also give you information on sail changes. For example you might be on a leg that gives you a course where the apparent wind angle lies in the cusp between the spinnaker and No.1. The polars will help you decide how to deal with that.

Also some trimming steps are guided by the relationship between the boatspeed and the target speed. For example, after a tack, you would typically go to full trim at about 1 knot below target speed. Below that you're trimming to accelerate out of the tack rather than for maximum speed (analogous to changing gears in a car).

Juniperskip
27-01-11, 18:30
Juniper - can you clarify that with regard to VMC and VMG pls ?

)Not being whingy; want to learn)

Didn't mention VMC or VMG on my offering??

Did you mean Visual Meteorological Conditions (VMC) or Velocity Minimum Critical (Vmc) ????

For VMG, your polars will give you your theoretical Upwind & downwind VMG targets for a given sail config/true windspd/angle. I also use VMG to waypoint a lot for racing and cruising to sail optimal angles but this is not polar related per se.

Sorry can't be more helpful......

sarabande
27-01-11, 19:17
VMC = best speed for the required (arbitrary) course.


I know quite a bit about the use of polar diagrams for racing, but I was wondering if you had a wrinkle about using separate polars for each sail to optimise VMG and VMC.

It sounds as if you are using the procedure in a different way from me, and I was looking for enlightenment.

thanks anyway.

Keen_Ed
27-01-11, 21:28
We have that on our new boat. Not used it yet though!

Might want to rethink that one. Deckman is know to be extremely powerful, with many functions for racing, but less (a lot, lot less) easy to use than other programs.

Take a look at Expedition - AIUI, a lot more user friendly with all the functionality. Or maybe even something like Seatrack.

Again, AIUI, the only people who need Deckman's fuctionality are Americas's cup/Volvo ocean race navigators. Unless you've basically got one guy spending all day navigating (and calibrating the instruments - a non trivial task), it's a sledghammer/nut situation.

Juniperskip
27-01-11, 21:55
VMC = best speed for the required (arbitrary) course.


I know quite a bit about the use of polar diagrams for racing, but I was wondering if you had a wrinkle about using separate polars for each sail to optimise VMG and VMC.

It sounds as if you are using the procedure in a different way from me, and I was looking for enlightenment.

thanks anyway.

Apologies for not appreciating yr knowledge level. The Raytech software (and Navman I think) refer to this as VMG on Course I believe. Thus I am guilty of moving to rely (yet again) on automation!!

The other VMC is a throwback to a previous career!!!

sarabande
27-01-11, 22:04
Yes, we are overwhelmed with TLAs !


At least, with aeronautical background and expertise you will be more than familiar with that excellent device, the pilot's flight computer - the knee-shaped one with no need for electrical backup !

Keen_Ed
27-01-11, 22:04
just discovered that B&G produce the Deckman program which just about covers most decent tech tools for sailing more efficiently. It includes a polar generator.

http://www.bandg.com/Products/Deckman-Tactical-Software/More-about-Deckman/

You have to be careful about generating polars from observed data. There's a lot of noise there, and working out what's actually going on is not easy. Big problems in working out true wind - calibration is critical, with all sorts of things like leeway, upwash etc having effects.

Far better to go to somebody with a VPP and get a set of polars off them. Then you can compare those to what you're seeing.

Juniperskip
27-01-11, 22:10
Yes, we are overwhelmed with TLAs !


At least, with aeronautical background and expertise you will be more than familiar with that excellent device, the pilot's flight computer - the knee-shaped one with no need for electrical backup !

And the 5 mile thumb!!!!!

rb_stretch
27-01-11, 22:10
When I used to race on big boats, one of the B & G nav displays always used to be on performance against polars expressed as a percentage. Polars were all held on a laptop integrated into the nav system, which allowed you to tweak your own polars if you could be bothered. The most useful thing was just to know at a glance when you way off the prediction ie. something was wrong.

The eeking out of the last few percentages points was not really used. Of course we all had a smile on our faces everytime we got over 100%.

sarabande
27-01-11, 22:20
yes, Ed, I have been reading up on Deckman in spare moments today. Given the variables which can be induced in the system from boat motion (surge and roll being the worst ones ?) and wind gusts and directional quirks, etc, I can see that the data logger will need to send a huge amount of info to the program, to reduce the fuzziness of the curves.

Creating a reliable and verifiable polar from empirical data would take ages. Using one derived from a VPP, using aerodynamic and hydrodynamic data from the architect is a much better starting point.

Getting the program to resolve all the variables on a single solution for one particular set of environmental and yacht data is a horrendous but intriguing mathematical challenge. Then when you have a set of polars, it is for an ideal boat at one particular state of loading and trim, hull cleanliness, sail selection and trim, crew position, etc. :eek:

Need to look at Expedition tomorrow !

Juniperskip
28-01-11, 08:42
I have used the Navman and raytech software in anger. Navman is really aimed at the top end racer and you need lots of setup time and a navigator that is a regular user and ideally a tablet pc in the cockpit with wifi link. The Raytech system is a compromise between navigation and racing but I find it much more user friendly. I am a Raymarine fan so biased. Their displays are more fexible than B&G but B&G have always produced a better mast pod setup.
Interesting last year at Cowes week. We raced class 1 with a B&G / Raymarine combo without a tablet display - many of the 20 something navs in our start spent the whole time on the pc in the cockpit. Don't know who does a better job but it is certainly a sign of the times!!!

Juniperskip
28-01-11, 08:45
You have to be careful about generating polars from observed data. There's a lot of noise there, and working out what's actually going on is not easy. Big problems in working out true wind - calibration is critical, with all sorts of things like leeway, upwash etc having effects.

Far better to go to somebody with a VPP and get a set of polars off them. Then you can compare those to what you're seeing.

You can download a number of "popular" boat polars off the B&G website.

Angele
28-01-11, 13:17
So, Magnum, I summarise:

If you are prepared to invest a lot of time and effort making sure your instruments are precisely calibrated, then you can spend your time at sea staring at readouts that tell you how well the boat is sailing relative to its theoretical maximum prediction.

If you couldn't be bothered, or you just prefer to spend your time enjoying your surroundings, just sit back, forget about polars and r....e....l....a....x :)

Magnum
28-01-11, 15:59
So, Magnum, I summarise:

If you are prepared to invest a lot of time and effort making sure your instruments are precisely calibrated, then you can spend your time at sea staring at readouts that tell you how well the boat is sailing relative to its theoretical maximum prediction.

If you couldn't be bothered, or you just prefer to spend your time enjoying your surroundings, just sit back, forget about polars and r....e....l....a....x :)
Good advice :)

However, I might just like to have a play with all this technology from time to time. I find it interesting, being a bit of a techie myself. However, relaxation will always be my priority :cool:

Magnum
28-01-11, 16:18
For interest here are our polar curves.

http://img34.imageshack.us/img34/3396/0117polaires.jpg.

Actually these are for a standard Bordeaux 60, so I hope our taller carbon rig and 3DL sails will do a bit better :)

Angele
28-01-11, 18:17
Good advice :)

However, I might just like to have a play with all this technology from time to time. I find it interesting, being a bit of a techie myself. However, relaxation will always be my priority :cool:

There's just no stopping him. He just can't resist the toys .......;)

sarabande
28-01-11, 22:24
I think the first thing that polar tells me is that the boat is not going to give you any sudden frights as you ease round a buoy or mark. No sudden accelerations or surge of power.

That means all the different sails will be relatively forgiving over a range of wind speeds, and you will not be forever changing or reefing if the wind pipes up or down a couple of knots.

Hmm, 60 ft , slippery hull, tall mast and decent sails... I'd be looking at quite a bit more speed with a spinnaker. Wait till you experience a run downhill and the spray from the bows coming straight past your ears in the cockpit with a noise like a 747 poised for takeoff - then you can come back and tell us what 'Relax' means....:)

Twister_Ken
28-01-11, 23:03
My polars here

http://i66.photobucket.com/albums/h269/twisterken/Untitled.jpg


How do I work out best VMG to windward and downwind (cruisy chute, not spinny as shown in the polars)

BrendanS
28-01-11, 23:07
Does anyone use this data in their day to day sailing? If so how?

If you want to understand polars, have a go at the online sailing races in another forum on here. When you get involved in those, polars suddenly start to make real sense.

Pinnacle
29-01-11, 15:49
My polars here

http://i66.photobucket.com/albums/h269/twisterken/Untitled.jpg


How do I work out best VMG to windward and downwind (cruisy chute, not spinny as shown in the polars)

I think they have been done for you......small red diamonds. :)

Twister_Ken
29-01-11, 16:47
I think they have been done for you......small red diamonds. :)

Doh!

Badgers
30-03-11, 10:55
Hi, I have been trawling the net.....(to date not in the right places!),
to find a polar curve diagram for my BMW/FARR designed Bavaria 32 Cruiser.

Can anyone point me in the right direction?

Thx
:confused:

sarabande
30-03-11, 11:45
try here?

http://polardiagram.com/node/13

and here

http://www.stentec.com/en/news/navigation/167-nieuwe-schepenlijst-met-polairen-wingps-4-voyager-


If you can find a PD for a similar boat, you won't be too far out for practical porpoises.

Badgers
30-03-11, 12:41
Thx... but not quite what I am looking for.

I really want the actual curve for my boat?

flaming
30-03-11, 13:12
Thx... but not quite what I am looking for.

I really want the actual curve for my boat?

An email to the designer ought to produce the goods.

Bosun Higgs
30-03-11, 14:16
Does anyone use this data in their day to day sailing? If so how?

Would love to do so if I could get a polar for my boat.

Badgers
20-04-11, 21:47
An email to the designer ought to produce the goods.

Attached in .pdf format for anyone that may want it!
regards

muyuu
02-06-11, 18:31
Interesting project:

http://polardiagram.com/

Angele
02-06-11, 19:30
Interesting project:

http://polardiagram.com/

Interesting, as you say. But, I can only find 11 boat models (from three manufacturers). Since they say the project started in March 2010, that works out at a little less than one a month.

I'm not holding my breath for them to get round to my boat model!

I suspect they got bored and gave up.

Edit: Oh no, tell a lie. They list 11 boat models, but don't even have the polars for all of them. Curiously, it also lists the maufacturer of both Hanse and Beneteau as Bavaria!

muyuu
02-06-11, 19:44
Interesting, as you say. But, I can only find 11 boat models (from three manufacturers). Since they say the project started in March 2010, that works out at a little less than one a month.

I'm not holding my breath for them to get round to my boat model!

I suspect they got bored and gave up.

Edit: Oh no, tell a lie. They list 11 boat models, but don't even have the polars for all of them. Curiously, it also lists the maufacturer of both Hanse and Beneteau as Bavaria!

Manufacturers could make this easy, they just don't seem to want to.

Resolution
02-06-11, 20:05
Does anyone use this data in their day to day sailing? If so how?

Yes, all the time when racing in the virtual Volvo.
No when sailing a real boat.

Dave100456
03-06-11, 00:10
You can find examples of Polar and Excel speed tables by going to
http://www.hallberg-rassy.com/
Select the HR 48 model and scroll down to bottom of the page that has the links (it won't copy & paste here)
Dave

muyuu
03-06-11, 08:32
You can find examples of Polar and Excel speed tables by going to
http://www.hallberg-rassy.com/
Select the HR 48 model and scroll down to bottom of the page that has the links (it won't copy & paste here)
Dave
Link to excel file: http://www.hallberg-rassy.com/hr48/HR48Boatspeeds.xls

Polar diagrams of all the models:

http://www.hallberg-rassy.com/HR310/HR310speeddiagram.shtml
http://www.hallberg-rassy.com/HR342/HR342speeddiagram.shtml
http://www.hallberg-rassy.com/HR372/HR372VPP.shtml
http://www.hallberg-rassy.com/hr37/speed_HR37.shtml
http://www.hallberg-rassy.com/hr40/hr40-speed.shtml
http://www.hallberg-rassy.com/hr43/speed_HR43.shtml
http://www.hallberg-rassy.com/hr48/hr48speeddiagram.shtml
http://www.hallberg-rassy.com/HR54/HR54speeddiagram.jpg
http://www.hallberg-rassy.com/hr62/speed_HR62.shtml
http://www.hallberg-rassy.com/HR64/HR64speeddiagram.shtml

BobPrell
03-06-11, 08:41
It seems some computers somewhere are crunching away to produce these.

Have any been verified by actual sailing and recording on the water and in the wind?

I know the designers would never lie to us but . . . are the computers really that good?

LewB
03-06-11, 10:34
Would anyone have, or be able to point me in the direction of a polar diagram for an Albin Ballad?

Or was it all done a with wet finger and which angle the coffee blew out of your mug!:rolleyes:

Thanks

Lew

ashonavega
03-06-11, 15:16
Would anyone have, or be able to point me in the direction of a polar diagram for an Albin Ballad?

Or was it all done a with wet finger and which angle the coffee blew out of your mug!:rolleyes:

Thanks

Lew

I don't know about the Ballad, but one certainly exists for the Albin Vega - Albin Vega Polar Diagram (http://albinvega.oddis.com/albin_vega_polar_diagram.html).

Ash

muyuu
03-06-11, 19:19
Several boats:

http://www.blur.se/boats/


1D35 (North, UK, Quantum)
606 (Gransegel, Hamel, North)
806 (trimguide)
A-35
A-40RC
Albin Express (Sten Bergqvist, Edman, North, Ottosson, UK Syversen)
Albin Nova (Blur)
Arcona 430
Beneteau 25 (North)
Capri 22 (Ullman)
Cal 40
Catalina 22
Catalina 36
Class 40
Dehler 38/Pacer 376
Dehler 44
Drake (Høj Jensen, North Tuning Guide)
Etchells (Doyle, North, Quantum)
Farr 36 (Farr Performance Prediction)
Farr 40 (Doyle, Farr PP, North, Quantum)
Farr 52
Farr 395 (Doyle, North)
Farr 1020
Fenix (trimguide)
Finn Flyer 36 Club
First 31.7
First 34.7 (Farr PP)
First 36.7 (Doyle, Farr PP, North, Quantum/pdf, UK/pdf)
First 40
First 40.7 polar1 polar2 (Farr PP)
First 44.7 polar1 polar2
First Class 8 (North)
H-båt (Edman, Henrik Lundberg. Høj Jensen, North)
IF (Edman, North)
IMS 43
IMS 53
IMX-40 (X-yachts)
IMX-45 jib only
IRC 32
J/22 (Haarstick, North, Quantum)
J/24 (Doyle, Haarstick, Jardine, North, Quantum, Shore, UK, Ullman)
J/27 (Ullman)
J30 (UK)
J/35 (Quantum)
J/46
J/80 (North, Shore, Quantum, UK, Ullman)
J/92 ()
J/105 (Doyle, North, Quantum, Ullman)
J/109 vpp-od/vpp-genua (Doyle, North, North England, Quantum)
J/120 (North, Quantum)
J/122 (polar + pleliminary IRC cert)
J/130
J/133 (vpp)
J/160
Landmark 43
Melges 24 (North, Quantum, Ullman)
Melges 32 (North, Quantum)
Mumm 30/Farr 30 polar1 polar2 (Doyle, Farr PP, North, Quantum + Cookbook
Mumm 36
Nelson-Marek 43
Olson 25 (Scot Tempesta)
Prima 38 (Quantum Tuning Guide)
Santana 20 (Ullman)
SeaCart
Sigma 33
Soling (Doyle, North, UK)
Sun Fast 3200
Sydney 36CR
Sydney 38 (North)
Swan 42 “ClubSwan” (North, Quantum)
Swan 45 (B&G, Hall. North, Quantum)
Swan 62RS
Swan 70
Tartan 10 (Doyle, North, Sobstad)
Ultimate 20 (Ullman)
VO 70
X-35 polar1, polar2 (B&G, North)
X-99 (North, X-yachts)
X-332 (trimguide)
X-332 Sport
Yngling (Doyle, Høj Jensen, North, Ullman)

Woodlouse
04-06-11, 18:18
It seems some computers somewhere are crunching away to produce these.

Have any been verified by actual sailing and recording on the water and in the wind?

I know the designers would never lie to us but . . . are the computers really that good?

The polars produced but the velocity prediction programmes are only theoretical figures. I think usually they are pretty accurate but most boats should be able to go one or two percent faster than the table would suggest if sailed perfectly.

It's quite mad when you get serious about the results of the VPP for different boats. At the high end a boat is considered slow if it can only reach 100% of it's theoretical potential. A fast boat will be doing 105% or more.