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.