Speed at different sailing points
- Thread starter Jared1048
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Kappy, I have found them very difficult to come by. Have looked a number oof times without much luck. For some reason Hunter Polar Diagrams are difficult to come by. If you find a site please share it.
Nodak
You can always make your own. Eventually, as you improve and tweak your targets should be come valid. Unless you are one-design, every boat is different anyway. Not hard with Excel and GPS.
http://sail-delmarva.blogspot.com/2010/06/speed-polars.html
http://sail-delmarva.blogspot.com/2010/06/speed-polars.html
Nodak, just found a post on this site from July 2005 that says Hunter never made them. Guess you'll have to get some freeware and make your own. Bummer!
Kappy that is about what I discovered when I looked for one for both my Hunters (33 & 41). The Dealer basically told me the same thing when I asked and I really do not have the inclination to make my own.
So I guess I just have to hope that someone else does have the inclination. 
Generally, what polars say is what sail trim books say, the same thing: MOST recreational sailboats go faster on a beam reach.
Unless you're a racing fanatic, I have found they're pretty useless on a day-to-day basis. And I have raced for quite some time.
As suggested, get to know your boat and you'll find those sweet spots on each point of sail.
Here's some background on polars: http://www.c34.org/wiki/index.php?title=Fin_Keel_Polar
Unless you're a racing fanatic, I have found they're pretty useless on a day-to-day basis. And I have raced for quite some time.
As suggested, get to know your boat and you'll find those sweet spots on each point of sail.
Here's some background on polars: http://www.c34.org/wiki/index.php?title=Fin_Keel_Polar
Pretty much!
I did it as a rainy day thing. I'm an engineer and it just seemed like fun. Practical value? Only as a learning process with a new-to-me boat. It suggested a few things that would have taken longer to learn without looking at the numbers. Like the fact that wing-and-wing is just as good VMG downwind for many boats, with a lot less work when it's blowing hard.
All you need to do is write down the data on random days when you believe you as well trimmed as you can be. When you've got data points from a variety of speeds and directions, make an Excel table and plot it polar. You will need to write a few simple calculations to smooth over the data gaps.
Well its a bit harder than that. First you have to know the true wind speed and angle and any given point of sail, than then you have to be sailing optimally. Plotting those two points with Speed over water gives you one point on the polar. And you need hundreds.
The ones provided by the designed or builder are usually the output from a VVP, or Velocity Prediction Program, which is a step in computerized sailboat design. Older boats were not often designed with such tools, so will not have polars easily available. Even then its a matter of target audience. Raced boat will have them, more pure cruisers no. Within the Beneteau family, the First series all have polars available, the Beneteau/Oceanus, no.
Well, yes, that is what I did. The trig requires that. I figured anyone who could set up the tables and understand the results would understand what numbers were needed, and which could be calculated from the others.
The problem with VPPs is that what they represent is generally unreal. Empty boat, perfect bottom, new sails, and flat water. Even then, they represent theory rather than actual in-water testing of a factory boat. Really tricky for multihulls and planing boats where hull speed offers less of a smoothing effect and speed is so dependent on helming and sea state. Interesting, but little more.
For those using iPhone there is a nifty little app called Sailsim. It is a simple simulator. Once you have input the data for your particular boat you can vary wind speed and direction to see predicted boat speed and heel angle. No idea how accurate it is but seems pretty close for my 326.
Looked at the App Dubai but I see no predicted heel or boat speed. Am I missing something?
Hi Novak
Once you have set your boat parameters in the set up menu, you should see a pic of your boat with tack and trim of sails. You can vary wind speed on left hand side of display rotate phone to set wind angle. Display then shows boat speed heel angle leeway etc. you can also switch to manual mode to trim the sails manually.
Once you have set your boat parameters in the set up menu, you should see a pic of your boat with tack and trim of sails. You can vary wind speed on left hand side of display rotate phone to set wind angle. Display then shows boat speed heel angle leeway etc. you can also switch to manual mode to trim the sails manually.
I had to go in again and look at the screen shots for this app and I see why I cannot see the heel or boat speed. How do you get to the Set-up on this App? I can find the model data but unable to get to set-up. That is why I cannot see the heel and speed.
That's a clever app. The trick is it needs your boats righting moment, and for that you would need an IMS certificate for your boat. And if you had that, you would already have your polars! It also must assume optimal foils, which is not usually true for cruising boats.
But it looks like I'll get 99 cents of fun out of it for sure.
Ahhh I found the set-up and have it working. Now the RMC might be a bit difficult to locate but it looks like it might be fun to play with. Thanks
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