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Polar Charts??

Aug 7, 2015
68
Oday 34 previous, O’Day 40 current Annapolis
Like many of us, I'm always curious whether I am sailing as fast as optimally possible. Does anyone have a set of polar charts for an O'Day '34 or 35? I think that I read somewhere that all manufacturers created them for each model of boat. I know this information is perhaps theoretical, but I'd like to know what might be expected.

Kind regards,
Lou K
 
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Oct 19, 2017
6,881
O'Day 19 Littleton, NH
Nov 8, 2007
1,392
Hunter 27_75-84 Sandusky Harbor Marina, Ohio
The best way to learn to sail optimally is to race! 2 years racing monthly in the Key West Naval Sailing Assn. still serves me in cruising on our H27. Sail trim, controlling heel, and rudder/sail trim are all transferable skills. The habit of always keeping my eye on the sails, the clouds, and on the wind over the water have also paid off big time. It’s surprising how many boats I see with poorly trimmed sails, excessive heeling, and rudders far off the centerline on Lake Erie in good winds.

Telltales and managing the “slot” were the only new ideas when I moved from dinghies to keel boats.
 
Nov 8, 2010
11,385
Beneteau First 36.7 & 260 Minneapolis MN & Bayfield WI
Like many of us, I'm always curious whether I am sailing as fast as optimally possible. Does anyone have a set of polar charts for an O'Day '34 or 35? I think that I read somewhere that all manufacturers created them for each model of boat. I know this information is perhaps theoretical, but I'd like to know what might be expected.

Kind regards,
Lou K
@LouisMK,

Sailboat designers would/will create polars for a boat if they expected it to race. Therefore, you seem them a lot for (USA builders) Beneteau Firsts, J-boats, and some Of the S2 Grand Slams. Almost never for cruisers, although in therory they could have. In O’day’s era few designers had this capability. It was developed in the mid 80s and became mainstream outside the big design houses (finot, Farr, etc) around 2000.

Polars are created by taking detailed parameters of the boat’s/rig/sailplan/keel design and running it through a computer simulation called a VVP (velocity prediction program). This program creates an X by Y array of values, with the axises being true wind speed and true wind angle, and the cells being boat speed.

People find it easier to read in polar form, hence the name.

They are very good for knowing what your upwind and downwind angles and boatspeed should be based on windspeed. It assumes optimal EVERYTHING. Clean bottom, correct boat and crew weight, good helming and trim, good sails, spinnaker downwind.

You CAN with great trouble make them manually, or even partially automated now, but that will only tell you what you actually do, and not what you should be capable of. So less valuable, except perhaps for downwind angles, which are harder than upwind to know without polars.

Unlikely, but if you race the boat in one of the big races (Newport Bermuda) and need a ORR rating, you would have to get the boat measured and rated. Over 500 bucks, but then get polars as part of the rating. US Sailing can arrange the same thing for about the same cost.

Be warned, there are several apps that profess to be able to generate polars. They are all crap.
 
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Aug 7, 2015
68
Oday 34 previous, O’Day 40 current Annapolis
Thanks guys, as mentioned, the reason for posting was to be able identify theoretical speeds at different points of sail under a variety of wind conditions. I know with enough time and a variety of wind speeds one can make their own charts. I had hope that one of the racers had either obtained the from O’Day eons ago or had investigated whether they were available from US Sailing.

Part of my goal was to see if my trimming was anything close to optimal & to have a metric to strive for. Will follow up w/US Sail to see what they do have.

Best, Lou
 
Nov 8, 2010
11,385
Beneteau First 36.7 & 260 Minneapolis MN & Bayfield WI
Thanks guys, as mentioned, the reason for posting was to be able identify theoretical speeds at different points of sail under a variety of wind conditions. I know with enough time and a variety of wind speeds one can make their own charts. I had hope that one of the racers had either obtained the from O’Day eons ago or had investigated whether they were available from US Sailing.

Part of my goal was to see if my trimming was anything close to optimal & to have a metric to strive for. Will follow up w/US Sail to see what they do have.

Best, Lou
I just checked, USsailing USED to offer polars as part of a so-called 'performance package' for around $300. This no longer available. I'm assuming that they could not get a good enough result without a full measurement. You still can get polars if you have your boat pulled out of the water and measured for ORR certification.

From 2013:
Polar Programs The offshore department has developed polar programs, including the Performance Package and Race Optimization Package, from the ORR rating rule technology. These polar programs are tailored to an individual boat’s sails and configuration. From these diagrams, target boat speeds and respective wind angles can be identified that will get the boat around the race course as quickly as possible. More information on performance packages can be found at http://offshore.ussailing.org/ORR/ Performance_Package.htm.

That link is dead.

Here is the form that they used. If one of your boat's sister-ships had been measured and rated, you were very very lucky and they used that boat's polars. If not, that just used what was on this form, which is not enough to generate good polars.

http://www.ussailing.org/wp-content/uploads/daroot/TrainingDept/PerfPack2013.pdf
 
Jun 25, 2004
1,108
Corsair F24 Mk1 003 San Francisco Bay, CA
I just checked, USsailing USED to offer polars as part of a so-called 'performance package' for around $300. This no longer available. I'm assuming that they could not get a good enough result without a full measurement. You still can get polars if you have your boat pulled out of the water and measured for ORR certification.
ORR is now the home of the VPP service, and USSailing relies upon their services. The link is here:
https://www.offshoreracingrule.org/orr-rule/polar-performance-package . It's $300. You have to measure and weigh your boat.

Also ORC.org offers some nice online services
http://www.orc.org/index.asp?id=25

You can get copies of rating certificates from them for free. You have to establish a free account with them.
http://www.orc.org/index.asp?id=21

They also offer copies of target speeds and polars for sister ships. They charge 20 - 50 Euros online for a copy. I never purchased from them, so I am not familiar with them.

I think that there are some significant limitation to buying the VPP for a sister ship. The predicted performance won't be as accurate if your boat differs. Adding weight, changing sail sizes, etc will greatly affect the computation of target speeds and angles.
 
Sep 11, 2015
147
Hunter 31 Marina del Rey
You will get better results if you create the polar yourself. Start with a known polar for a boat similar to yours. For example, for my H31 I started with a HR31 polar. Ideally you want a boat that has a similar PHRF rating to yours. Then you need wind and speed inputs (it is OK to use GPS speed of currents are weak in your sailing area) and start adjusting it. Typically you would adjust down as the publish polars are optimistic. At the end of the exercise, you will have a solid polar, for your boat and sail setup, weight, etc. You can then use that for weather routing.
 
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