Polars
- Thread starter dehler25
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Went looking a while back and never did find a single one. Clearly polars are a boat-sail inventory/age-crew skill sort of thing which is why I don't think any body bothers making a "standard" polar for model x. Your best bet is to get some circular graph paper and start recording data. One page for each main-foresail combination is my recommendation as it is going to take a while to get enough data to tell anything. If you try putting it all on one graph you (well I would) eventually forget to label the data points and have to start over. FWIW
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You got me interested again. This app can "learn" the polars for you boat!!!!
http://www.sailtimerapp.com/MoreDetail.html
good luck
You got me interested again. This app can "learn" the polars for you boat!!!!
http://www.sailtimerapp.com/MoreDetail.html
good luck
Hi.. Sorry the late reply I just saw this.. Yes I to would be interested. Raytech (Full licenced version) fully connected can actually generate these for you but it takes time and everything needs to be right. I have done it a couple times and still need to work on it. For me I need to boat clean and my typical sailing conditions with no added current so that these things can be taken into account in real time. Im not sure how or with what you intend to use your Polar when you get it but Raytech is very good but also very complicated. Once you have this information you can also use the Laylines and VMG becomes much better. Hunter by rights should supply the Polar, but I when I approached them they maintained this was proprietary design information, so it does exist and they do or at least did have it. Perhaps a few more approaches to Hunter might see this change, or perhaps someone knows someone who can add some weight. Good luck
Yea Polars are not so complicated in there us, and yes you are 99% right its about hull and keel, but also speed. However when sailing of course the Hull and shape in the water changes (ie water line length for example), as does the power provided by the sails, the sea and the current. Polars are one of many factors and typically the only one not readily available to tell you the best way to go, to make the best VMG. So when you have or create polar, and with some software you add this to known SOG (for your boat) to a given wind angle and sail set, then combine that with the current, which is already known, the wind strength and direction ( already known), you now have 99% of the tools to produce the best possible VMG to a known way point or route. It is interesting and I am by no means an expert, but it did teach me not to pinch the wind as much, and has given me a vague rule that in my case for every 10 degress I am off my run line I must go 1 knot faster to arrive at the same time. If you have the current and tides and your software can deal with all of this, you will find you will leave at different times and travel in different directions to that which you probably otherwise would have gone. I need to play a lot more in this area, and typically only do it for interest at this time. Im in no hurry.
Polars created by a boat's designer are done so by modeling the boats performance with a Velocity Prediction Program (VPP), a suite of software that models the hull, appendages, rig, and upwind and downwind sailplan. It calculates flat water boat speed over a range of wind angles and speeds.
Racers and performance oriented sailors like that because it gives them targets, in particular upwind speed and downwind angles. Downwind values are meaningless if you are not flying a spinnaker designed for your boat.
If you have polars for your boat, you will need great sails, a correctly sized crew, and sail well to hit them.
There are ways to generate polars from observer performance, but this can suffer from GIGO (garbage in - garbage out) where if the input is not good; measured performance or how you're sailing; the polars will be bad. But its a place to start.
You CAN have polars created for your boat; but its not cheap. If you are lucky, someone has had it done for a sister ship... this happens if someone wants to seriously race it.
Polars ARE needed for weather routers to work; and there are some good ones for the ipad and the like. But remember again, that route will be meaningless if you are not using spinnnakers when sailing off the wind.
Racers and performance oriented sailors like that because it gives them targets, in particular upwind speed and downwind angles. Downwind values are meaningless if you are not flying a spinnaker designed for your boat.
If you have polars for your boat, you will need great sails, a correctly sized crew, and sail well to hit them.
There are ways to generate polars from observer performance, but this can suffer from GIGO (garbage in - garbage out) where if the input is not good; measured performance or how you're sailing; the polars will be bad. But its a place to start.
You CAN have polars created for your boat; but its not cheap. If you are lucky, someone has had it done for a sister ship... this happens if someone wants to seriously race it.
Polars ARE needed for weather routers to work; and there are some good ones for the ipad and the like. But remember again, that route will be meaningless if you are not using spinnnakers when sailing off the wind.
I used a NMEA2000 to wifi converter to gather data on my laptop to help verify and calibrate the polars on my Catalina 27, here is a plot for boat speed upwind with a 150% Genoa. You can find links to a lot of polar data (including non-spinnakers polars) at https://sailingpolars.com/
Attachments
I have an '06 Hunter 38. I could not find polars for it. I'm using the H375 polars. Either that was a much faster boat or I'm a lousy sailor as PredictWind consistently over estimates my speed.
OpenCPN plugin can calculate polars for you if you feed it the right data.
The new PredictWind DataHub is supposed to generate polars for your boat by gathering data over time. A friend installed one on a sister boat to mine and is using it now with Starlink. He's talked to PredictWind tech support and it's supposed to even know when you're motoring vs sailing by measuring voltage, so it ignores data when motoring to keep from polluting the sailing polar data. Supposedly PredictWind will then use your boat's collected polar data to do your weather routing.
Will be interested to see how this goes. The Raymarine Axiom has a database of polars in there, but for Hunters it's not a large sampling of boats - he's using the old Hunter 40.5 on the chartplotter while he generates his own polars for his MH40 via the DataHub.
DataHub · PredictWind
Will be interested to see how this goes. The Raymarine Axiom has a database of polars in there, but for Hunters it's not a large sampling of boats - he's using the old Hunter 40.5 on the chartplotter while he generates his own polars for his MH40 via the DataHub.
DataHub · PredictWind
That Predict Wind DataHub sounds pretty good, I have a fully Licensed Version of Raytech running now for some years. It also can generate Polars and does reasonable job. What I found most usefull and a good learning curve was how often I would infact be better off with a greater wind angle. Raytech will plot a route that is typically longer than my manual one, but often quicker based on computing predictions. However, the trouble is when you run it against predicted winds the wind angle prediction is often wrong and hence then so to is the predicted route. I do it more for fun education and to keep me on my toes maximizing performance in the cruising ethos. That said I just had a look at the above link and got the polar for my Hunter 49. The light wind Polar 6knts figures there are defiantly wrong. For example, my boat and I would expect most others (excluding racing boats) goes better up wind forward of the beam, probably around 70-75 degree mark, same goes in 8knts but to a lesser extent. I believe this is due to suction airfoil factor of light winds forward of the beam increasing apparent wind.. The 10-12-14knt winds seem pretty good, but by the time I get to 16 knts true (which could be 22-25 apparent) Im starting to reef and then at 20 true Im definitely reefed. So while I believe the polar from sailing polars is pretty good from 10knts up i have modified mine to reflect more what I tend to do, and in fact I tend to go slower in say 16-18knts of true wind especially if the wind angle is less than 110. I guess Polar's are for the racing guys, not cruisers, but a cruising Polar is also helpful. Interestingly I have also reached & exceeded their top SOG of 10.32knts and that wasn't in 20knts (or sliding down the back of a wave ) 
The new Raymarine Axiom have polars in their data base it has polars for my Hunter 35.5 and it’s excellent to use
LIGHTHOUSE VESSEL POLAR MANAGER
Axiom displays running LightHouse 4.5 or higher include over 500 sets of Polar Performance Data for popular sailing hulls preloaded. If your hull is preloaded in Axiom, choose your yacht brand and model and enjoy the advanced features polar performance data enables, such as tack angles to achieve optimum VMG upwind and downwind, time and distance to tack, and the percentage of polar boat speed being achieved. The latest list of Axiom's preloaded Performance Polars in the LightHouse operating system is available in this knowledgebase article.
LIGHTHOUSE VESSEL POLAR MANAGER
Axiom displays running LightHouse 4.5 or higher include over 500 sets of Polar Performance Data for popular sailing hulls preloaded. If your hull is preloaded in Axiom, choose your yacht brand and model and enjoy the advanced features polar performance data enables, such as tack angles to achieve optimum VMG upwind and downwind, time and distance to tack, and the percentage of polar boat speed being achieved. The latest list of Axiom's preloaded Performance Polars in the LightHouse operating system is available in this knowledgebase article.
Polar Performance Data | Online Guides | Raymarine
Upload your boats polar data here. Raymarine uses polar information to calculate the fastest choice of path for the current wind speed and direction helping you make the most of your time on the water.
www.raymarine.com