Tobago 35: Polars

[kiltym]

Anyone have or know where to get a polar file for a FP Togabo 35?

[barnakiel]

For what application?

BTW I have never seen one. You sure it exists?

Make yours.

b.

[kiltym]

Originally Posted by barnakiel

For what application?

BTW I have never seen one. You sure it exists?

Make yours.

b.

To use in routing software for longer trips.

I received a 20kt polar from FP, out of the original FP Tobago brochure. It's a start. I have attached it here.

Would like to make my own, and looking for some software to help out with the process since a computer should be able to build a decent one given enough time on the water.

[barnakiel]

Originally Posted by kiltym

To use in routing software for longer trips.

I received a 20kt polar from FP, out of the original FP Tobago brochure. It's a start. I have attached it here.

Would like to make my own, and looking for some software to help out with the process since a computer should be able to build a decent one given enough time on the water.

Yep, most racing software will build them for you provided your data (wind, compass, log, etc.) is fed into the software. Then you must sort the outcome by the sail choice used and you may sort it out by the sea-state.

I use polars of various boats for weather routing. Remember you will want RT (not delayed) gribs in regular intervals - the less the interval, the more accurate the result. It also takes quite some time to learn the specific software and its quirks and limitations to use wx routing functionality effectively. Most boats, if sailed by actual VMG fare at least nearly as good as those that are wx routed. But it is fun, and some people are simply pressed for time (or else scared by the weather) and so it is a great thing that such things as gribs and polars and PC's exist. Other pieces of software you may like to have onboard are a wefax receiver, a digital pilot charts atlas, and a good grib downloader. I have not yet found a good digitized support for ocean currents but there is good information strewn on the web. Get it - you do not want to get that extra 0.5 of a knot from your wx routing skills only to be wasted by an opposite ocean current that could otherwise be avoided!

A good starting point is to extrapolate from the polar you attached and while observing your boat you will be able to make some very educated guesses into what speed is likely in any given conditions and which gybe/tack takes you to the best location for tomorrow's conditions. Two generalizations that can help you upfront will be that in light conditions, as soon as the boat starts going, you will achieve good speeds close hauled and up to beam reach but not on the 'very broad' reach and running; as the wind builds beyond her comfort zone, you will still be able to upkeep good speeds broad reaching and running but not beating and close hauled. Most polar data of manufacturers omits this fact - they all think out there in the design office that we are sailing on a lake, really ;-) Another general rule is that you are sailing a cat and so you will be sailing broad reaches rather than runs and so you must tell your routing software this is the case; otherwise, right out-of-the-box, most software will think a run is such a fast track, which actually it is not.

Finally, do not miss the big picture - features you will see on wxfax, but not in the gribs - they may make you chose a track contrary to wx routing advice in many cases - to avoid some wx features or else to seek them.

Bueno. My two cents. Have fun using the toys and sail safe!

Cheers,
barnakiel

[kiltym]

Thanks for the thoughts, all good advice, I agree.

I will try to use the baseline from FP and go from there, as I don't seem to find much else out there.

Certainly using some software to "record" the data will be much more efficient then me paying so close attention every time we go sailing.

If I find something that works for me, I will post the info here as well.

[barnakiel]

This guy/lady here describes the process of collecting the data and making the polar:

Create Polar Diagram - Oppedijk.com



Cheers,
b.

[kiltym]

Originally Posted by barnakiel

This guy/lady here describes the process of collecting the data and making the polar:

Create Polar Diagram - Oppedijk.com

Yes, had seen this site.

It looks like this software will do what I am looking for. It's all in French so will take a bit of time to figure it out, but seems to record NMEA data and create polars from it.

Polaires auto

[barnakiel]

Remember what you do want is probably a software that will give you a polar FILE rather than a polar diagram only. All wx routing software uses files, not diagrams.

Software that outputs to spreadsheet is often ok as spreadsheet files can be converted to polar files for most software.

b.

[kiltym]

Originally Posted by barnakiel

Remember what you do want is probably a software that will give you a polar FILE rather than a polar diagram only. All wx routing software uses files, not diagrams.

Software that outputs to spreadsheet is often ok as spreadsheet files can be converted to polar files for most software.

Agreed. The software I linked to does this, in 3 different formats so you can load into routing software, like Maxsea or QtVlm.

It also shows the diagram.

[barnakiel]

+1!

You probably have VPP software onboard. This one helps to preplan the offshore voyage. It is basically digitized Pilot Charts data plus some basic wx routing/wx stat reporting app.

b.

[Diogo Cyrineu]

10 years after, did u made the polar kiltym?

If yes, can you share?

Thanks.

[kiltym]

Originally Posted by Diogo Cyrineu

10 years after, did u made the polar kiltym?

If yes, can you share?

Thanks.

No, never did it.

But sailed for 9 years on our Tobago, from Annapolis, MD to French Polynesia. Reality is always different then the best laid plans, so don't get to hung up on the polars. She is a solid boat, and took us across the Pacific with no major issues, but it was not the most comfortable ride based on her size and weight.

We crossed from the Galapagos to the Gambier in 21 days. She did just fine.

[JBP]

The free app SailGrib includes a lot of polars, you might find one that is close that you could start with. The paid version will let you calculate your own based on parameters.