Boat Polars

[Viking 28]

Hi folks
I own a Viking 28 sailboat 1974
I have been trying to find the polar information for this boat but it has been very very difficult.
Can anyone help?
I have heard that you can substitute a similar boat as well but that seems difficult to find as well.

[NormanMartin]

Have you tried this:

https://sailboatdata.com/sailboat/viking-28

Sail Calculator Pro v3.54 - 3200+ boats

If you look at similar sized boat PHRF numbers you can get a sense of relative performance. I looked on the phrfne.org site and didn't see a Viking 28 listed or I'd have gone into more detail.

What do you have in mind for the information?

[Viking 28]

Hi
Thank you, to be honest i dont really understand what polars are i know it has to do with potential boat speeds at different wind angles.
I purchased raymarine instruments that will give you laylines but i need to input the boat polars for a Viking 28 ( sorry if i posted for a viking 27)
Or if i can find a similar boat i can use that and it will work reasonably well.
So far i havent been able too.
It seems like much newer race boats polars are available but for my 1974 viking i have had no luck.

[NormanMartin]

The polars are used mostly by high end racing programs or wannabe high end racers... in my opinion.

What is your experience level and cruising/racing area?

Norm
Cape Cod

[jdazey]

Originally Posted by NormanMartin

The polars are used mostly by high end racing programs or wannabe high end racers... in my opinion.

What is your experience level and cruising/racing area?

Norm
Cape Cod

Also for weather routing.


Cheers,

[Viking 28]

Anyway guys
I would just like to know if anyone can help with that info or if anyone can suggest what boat I could use as a substitute
Thanks.

[Dave_S]

Originally Posted by Viking 28

Anyway guys
I would just like to know if anyone can help with that info or if anyone can suggest what boat I could use as a substitute
Thanks.

If there isn't one for your boat, join the club, I'm afraid there aren't polars for all boats and if you don't have the original sail plan or you have modified the setup in anyway then the factory polars or someone else's won't be accurate anyway.

You have 2 choices, one you rough out your own and edit as you go or two search through polars in the links above and pick one you feel is close and edit it as you go but you will need to understand what they are and how to read them first. They are not complicated once you get your head around it and you will already have a fair idea in your head how it sails in what situations, you just need to enter that information.

[seandepagnier]

I did some stuff with the sailboat transform (an equation that pretty well describes boat speeds for typical boat) It won't be accurate for strange boats/rigs. With very few data points can give complete polars. It's built into weather routing plugin of opencpn.


polars are really complicated because they are affected also by which sail plan, how the boat is sheet, fouling, weight distribution, even air temperature and humidity, but more importantly sea state which is multidimensional. It's really difficult and, you may be in conditions < 1% of the time that have really different dynamics and results for polars, consider the case of significant primary and secondary swell.