PCSail - Excel sheet to make VPP for Sailing yachts

[plefneski]

I was able to get the PCSail spreadsheet to work. First of all you need to have the Solver add-in installed for excel. Follow the word document especially with respect to the hull, sail input values and the values on the runit tab. My boat is still in the water so I cannot get specific measurements for everything but I made some guesses on some of the measurements. I had to do a bit of investigation because the macro was ending without any error message. I found that there was reasonability logic built into the macro that would stop it if hull resistance and drive calculations do not make sense. After adjusting some of the hull measurements I was able to get the macro to complete. The polar table that it created looks reasonable but it will take some time to verify it's accuracy.

[rgleason]

Thank you Paul, that's very helpful. It appears using NavMonPc is reasonable, but as you indicate, the recordings have to be taken during long stretches devoid of changes in wind, course, speed, sea state and current and will need post processing, and the instruments need to be calibrated.

Do you know which nmea data should I be using? I assume some of it is from GPS, fluxgate compass, speed transducer and masthead wind instruments :
1. True or apparent wind? - from wind instrument
2. Boat speed? - from speed transducer or GPS?
3. Boat course? - from fluxgate compass or GPS?
4. Position with wind? - from GPS and wind instrument? (current?)
5. There are lots of variables and choices, but someone has probably figured out the best way to get good data.
5. The effect of current has me stymied, I've seen the result of a 2.5 knot current in my tacking track, and it is astounding at first. How do I accommodate for that? --Record only during slack??

[rgleason]

plefneski wrote:

PCSail.xls -After adjusting some of the hull measurements I was able to get the macro to complete. The polar table that it created looks reasonable but it will take some time to verify it's accuracy.

That is great. What did you answer when there were circular references? I am going to have to see if I have Excel "solver" installed. I found some of the flexibility in the spreadsheet (centerboards, props with apertures and without, etc) a little daunting and did not see where we turn on those choices. Sharing your experience and any suggestions would be appreciated.

[rgleason]

In the Oppedijk Polars link above Create Polar Diagram - Oppedijk.com Some of the data used is listed:

1. BEAT ANGLES: The best course to steer for an upwind course (usually around 45 degrees) BEAT VMG: The Velocity Made Good, the speed made directly upwind (always less then boat speed)
2. RUN VMG: The Velocity Made Good, the speed made directly downwind (always less then boat speed)
3. GYBE ANGLES: the best angle to sail downwind with the best VMG, usually around 150 degrees with little wind and potentially 180 degrees in a lot of wind.

Isn't VMG calculated? Aren't VMG upwind and downwind are two different beasts?

[jonasaberg]

Originally Posted by plefneski

I was able to get the PCSail spreadsheet to work.....

Great work. Exactly which version of Excel are you using?

/Jonas

[Paul Elliott]

The "proper" way to make these measurements is to use water-referenced data: Speed through the water and apparent wind speed / angle. This way it doesn't matter which way the current is running. As long as you can measure or estimate your leeway (the course through the water you are sailing vs the direction you are pointing) you can calculate true wind speed and angle. Your instruments need to be well-calibrated to obtain any real accuracy, especially for the true wind numbers. For that matter, many speed transducers read differently on the opposite tack. Again, calibration is critical. Wind instruments are also notoriously affected by heel angle and upwash from your sails.

If you can determine the current, then instead of the water-speed you can use the SOG from the GPS. You need to do the math to subtract out the current vector.

About wind calculations, you need to know your leeway because the wind instruments measure relative to your bow, but you are not usually sailing exactly where your bow is pointing. This is critical when calculating true wind speed and angle. I believe that the correct method is to use true wind, although some polars do use apparent wind. I don't know if the apparent wind polars include the leeway factor, or if they just do the simple true to apparent conversion without accounting for leeway.

[rgleason]

Jonasaberg wrote:

... I have used Sailfish Yacht Analyser a lot too. Wrote long bug testing reports and sent to them for version 1, 2 about ten years ago or so.

I don't think it is actively developed. They stopped replying to feedback mails several years ago. The newest OS in the bug report form is Windows XP (if you disregard Windows2003, guess not too many are using that one) No option for vista or Window 7.

That said, it is really easy to use.

Good News! I wrote Sailfish and received a quick response. ... use IE for www.techsail.com
it works much much better! Hopefully Kjell will join the forum and start using Opencpn.

Hi Rick, Thanks for your feed back. The latest version is 4.1!

The download page is designed for Internet Explorer. Other browsers will not display the download page correctly.

Download link: http://www.techsail.com/downloads/sya4setup.zip

About the Windows 7; the current version is actually built for WindowsXP. We are migrating the code to a Windows7 version that is planned to January 2013.

Your opinion about range will be considered. (Hence, the math is less accurate outside the current range)

The NMEA AciticeX is also developed for WindowsXP (currently not planned for upgrade)

The efficiency it take from the definition in IMS manual (www.orc.org)

I have not used the OpenCPN but I will look at it.

Best regards

Kjell Backudd

I think this resource is the easiest way to build your own starter Polars if you don't have a manufacturer's version. It seems to provide a complete set of target speeds etc. and the OpenCPN website probably should have a link to it, under Resources-Links VPP Polar Creation

[jonasaberg]

That's great. Should have checked it out before being pessimistic about it.
It installed fine on my Win7 machine, and seems to run fine also. (It does cost a bit of money though...)

/Jonas

[kiltym]

This is another tool (free) that can create Polars, if people are interested. Someone that works on the routing tool (QtVlm) pointed me to it.

It is all in French, so if you don't know French, you will need a little Google Translate to get things figured out, but it is not too complicated.

I use NavMonPC to route the NMEA data to a virtual COM port that then this software reads to create and record the polar data.

Just FYI as it may be useful to others on this thread:

Polaires auto

[rgleason]

Thanks.

Polaires Auto - English Translation - main page

Polaires Auto Forum - English Translation -has Maitai participating with QtVlm, good discussion of polars, nmea data to use, file types, improvements to recording and filtering, most recent program version is attached at the bottom of the forum (most recent). Users are testing in real world.

Looks like it might be a good program for recording nmea data, perhaps Maitai will comment on it. ...more later.

[maitai]

I have tried it a bit but only "offline" (no NMEA data concerning wind on my boat ). The comments from the french forum users are very good.

It records boat speed, TWS and TWA and generates a polar. You can specify various parameters (sea state, sails, etc). It seems it has a good algo to get rid of irrelevant values (surfing, etc).

I will post something in the forum and surely the author will be able/interested to say more.

[tiersp]

Hello,
I am the conceptor of polauto.
If some english sailors are interest with this software i can try to do an english version.
but as you see my english is not very good !!

[JesperWe]

Originally Posted by tiersp

Hello,
I am the conceptor of polauto.
If some english sailors are interest with this software i can try to do an english version.
but as you see my english is not very good !!

I speak decent English and French and have no polars for my boat ...
Are you using any tool for translations?

There is GNU Gettext for Delphi and C++ Builder ...

[tiersp]

Hello,
I have post an english version of Polauto on the french forum
It's the thread give by Kiltym above.

[rgleason]

Maitai wrote

I have tried it a bit but only "offline" (no NMEA data concerning wind on my boat ). The comments from the french forum users are very good.

It records boat speed, TWS and TWA and generates a polar. You can specify various parameters (sea state, sails, etc). It seems it has a good algorithm to get rid of irrelevant values (surfing, etc).

Thank you Maitai for your 2 posts and Tiersp for joining. Maitai's description sounds ideal. Indeed, I am language challenged, and an english version would make it much easier for me. Thanks to JesperWe for the GNU translation suggestion, perhaps this is the Polar tool we could all use!
- Start with a VPP Polar from Sailfish or PCsail.xls to generate a starting set of polars and then use Polauto to refine it on the boat in real world conditions.

-Should we be doing planned runs with no changes in (course, sails, etc) and in tideless conditions?

PS I will be watching the translated version of Polauto forum too, and perhaps try some high school french from long ago....


Polaires Auto - English Translation - main page

Polaires Auto Forum - English Translation -