Kevlarpirate
Member II
Does anyone know of polars for the 46?
Thanks
Thanks
Polar Diagram E46
- Thread starter Kevlarpirate
- Start date
US sailing definately has one, but you could look at mine first...
US Sailing has a rating for my boat when it was Esta Es III owned by Gene McArthy and raced in the Chicago to Mac race. 2001?
I have a set that I have constructed here with a program that I have, it looks right, but I am trying to track down more data to plug in to get it even closer. There is one minor mathmatical issue I think in the model, see what you think.
On this subject I have the original IOR rating sheet from my boat. Anyone have any idea where I could find a set of definitions for all of the abbriviations on it. Most of them seem different than the ones on the IMS rating system. I would like to get the definitions all figured out converted to IMS definitions that my program accepts for the polar figuring, and generate an even better polar.
However here is what I have so far....
www.svpneuma.com/speed
Guy
US Sailing has a rating for my boat when it was Esta Es III owned by Gene McArthy and raced in the Chicago to Mac race. 2001?
I have a set that I have constructed here with a program that I have, it looks right, but I am trying to track down more data to plug in to get it even closer. There is one minor mathmatical issue I think in the model, see what you think.
On this subject I have the original IOR rating sheet from my boat. Anyone have any idea where I could find a set of definitions for all of the abbriviations on it. Most of them seem different than the ones on the IMS rating system. I would like to get the definitions all figured out converted to IMS definitions that my program accepts for the polar figuring, and generate an even better polar.
However here is what I have so far....
www.svpneuma.com/speed
Guy
That is the one!
Yes, US Sailing will have the Polars for Esta Es-she was issued an Americap rating-derived from IMS, and so these polars exist. IMS used many of the same definitions/abbreviations as IOR, but if you would like some help, I would be happy to explain those to you...,
Your polars look very close, though-were they derived from IOR? IOR based polars were close, but the IMS ones were much better-most of the time. The good news is that the polars for a boat of this type are more accurate than those for higher perfomance, planing types.
I did not realize Esta Es was gone-but that was obviously the boat I was thinking of...
Let me know how I can help with anything going forward-and good luck,
S
Yes, US Sailing will have the Polars for Esta Es-she was issued an Americap rating-derived from IMS, and so these polars exist. IMS used many of the same definitions/abbreviations as IOR, but if you would like some help, I would be happy to explain those to you...,
Your polars look very close, though-were they derived from IOR? IOR based polars were close, but the IMS ones were much better-most of the time. The good news is that the polars for a boat of this type are more accurate than those for higher perfomance, planing types.
I did not realize Esta Es was gone-but that was obviously the boat I was thinking of...
Let me know how I can help with anything going forward-and good luck,
S
Really??? Thanks Seth!
Ok I have uploaded the entire IOR certificate in XL format to the same place on the web. Any of the abbriviations that you can assist with would be wonderful. There are some of them that I had really good guesses at, and other that perplexed me.
Thanks for the help Seth.
Esta Es is now Aiki, has had the interior removed, been completely retabbed, interior put back in, the wiring completely redone, the plumbing redone, the nav station completely remade, the galley refaced, Rig completely gone over, new exhaust system, and will be shot throughout the interior with new polyeurathane this weekend. (hey that brings up a question that you can answer!!!). What in the heck was the stuff that they put on for a finish at the factory, does not behave like any varnish I have ever seen, I surmised that it must have been polyeurathane?
Then a new headliner, and some nice carpet, and we have a new home, that should be a bit faster than the E-39 that we did 45,000 miles on.
Thanks for helping on this, I really appriciate it. I have done a lot of racing, but someone else always dealt with the handicap stuff....Since I haven't raced my own boats in a competitive venue, I haven't seen it....Especially the IOR stuff.
Thanks,
Guy
Ok I have uploaded the entire IOR certificate in XL format to the same place on the web. Any of the abbriviations that you can assist with would be wonderful. There are some of them that I had really good guesses at, and other that perplexed me.
Thanks for the help Seth.
Esta Es is now Aiki, has had the interior removed, been completely retabbed, interior put back in, the wiring completely redone, the plumbing redone, the nav station completely remade, the galley refaced, Rig completely gone over, new exhaust system, and will be shot throughout the interior with new polyeurathane this weekend. (hey that brings up a question that you can answer!!!). What in the heck was the stuff that they put on for a finish at the factory, does not behave like any varnish I have ever seen, I surmised that it must have been polyeurathane?
Then a new headliner, and some nice carpet, and we have a new home, that should be a bit faster than the E-39 that we did 45,000 miles on.
Thanks for helping on this, I really appriciate it. I have done a lot of racing, but someone else always dealt with the handicap stuff....Since I haven't raced my own boats in a competitive venue, I haven't seen it....Especially the IOR stuff.
Thanks,
Guy
Quiet Magic
Member II
what is a polar diagram?
Please excuse my stupidity but, what is a polar diagram? Does it have to do with racing ratings?
Please excuse my stupidity but, what is a polar diagram? Does it have to do with racing ratings?
Nothing stoopid here (except me)
A very reasonable question. Polar charts (or diagrams) are a graphic depiction, also given in table format, of expected speeds at a range of wind angles and wind speeds for given boat design.
These speeds are derived from one of the racing measurement formulas now in use-using a program called VPP (velocity prediction program). In this program, certain measured dimensions from the actual boat (or a sistership), such a Length, Beam, Width, LWL, etc. as well as rig and sail dimensions are entered, along with some flotation measurements to indicate weight, and the result is a very accurate speed prediction. Designers will use this formula to predict performance of a new design by entering the DESIGNED values for these specfic measurements, and get "pro-forma" Polars.
Cruisers can use them simply to get an idea of what they can expect from their boats-or to have an idea how well they are sailing at any given time. Racers WILL use them to tweak trim and weight placement (and sail selection) to get as close to the boats' potential as possible.
It is common to laminate these tables and tape them near the cockpit, so that will reasonably good instruments a sailor can see if he is close to the potential of the boat in a given condition.
If you have a design that has been around a while and raced, these records probably exist in the US Sailing Database, and may be purchased.
If you have a one-off design you would either have to ask the designer to prepare a pro-forma measurement, and produce the Polars (for a fee, of course), or have it actually measured by a designated measurer (also not free).
Currently the IMS and IRC are being used as the measurement rules under which boats are measured (meaning these rules spell out which measurements are to be taken and how), and these numbers fit into the VPP.
In years past, the IOR and MORC rules also could produce Polar charts-although not as accurately.
This is a somewhat basic explanation-I hope it helps!
Cheers,
S
A very reasonable question. Polar charts (or diagrams) are a graphic depiction, also given in table format, of expected speeds at a range of wind angles and wind speeds for given boat design.
These speeds are derived from one of the racing measurement formulas now in use-using a program called VPP (velocity prediction program). In this program, certain measured dimensions from the actual boat (or a sistership), such a Length, Beam, Width, LWL, etc. as well as rig and sail dimensions are entered, along with some flotation measurements to indicate weight, and the result is a very accurate speed prediction. Designers will use this formula to predict performance of a new design by entering the DESIGNED values for these specfic measurements, and get "pro-forma" Polars.
Cruisers can use them simply to get an idea of what they can expect from their boats-or to have an idea how well they are sailing at any given time. Racers WILL use them to tweak trim and weight placement (and sail selection) to get as close to the boats' potential as possible.
It is common to laminate these tables and tape them near the cockpit, so that will reasonably good instruments a sailor can see if he is close to the potential of the boat in a given condition.
If you have a design that has been around a while and raced, these records probably exist in the US Sailing Database, and may be purchased.
If you have a one-off design you would either have to ask the designer to prepare a pro-forma measurement, and produce the Polars (for a fee, of course), or have it actually measured by a designated measurer (also not free).
Currently the IMS and IRC are being used as the measurement rules under which boats are measured (meaning these rules spell out which measurements are to be taken and how), and these numbers fit into the VPP.
In years past, the IOR and MORC rules also could produce Polar charts-although not as accurately.
This is a somewhat basic explanation-I hope it helps!
Cheers,
S
Looks Like this:
This one is true wind, there is another that is apparent wind which is a bit more usefull in the cockpit in my opinion.
This one is true wind, there is another that is apparent wind which is a bit more usefull in the cockpit in my opinion.
Attachments
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polar for eyo.jpg
Why didn't I think of posting that???
D'oohhh! Thanks Guy-that is a Polar chart. There is usually a table, or spreadsheet format as well when you get these.
It is also true that they are usually calculated for both True and Apparent wind speeds and awind angles, but I would differ on the value of the apparent wind data-Apparent wind it is quite a bit less accurate in that the apparent wind angle changes significantly as you accelerate, slow down, etc. If you hit a big wave, and slow down, the apparent wind speed slows and moves aft-putting you on a broader reach with less wind-if these were actual changes in woind speed and direction they would be of more value-but in fact they are quick and momentary, but will indicate better or worse than you can really expect from your boat.
Another problem is with upwind sailing (and downwind gybing). Although you may be sailing at 28-35 degrees or so to the apparent wind (upwind), your tacking angle (difference in compass heading from one tack to the next) is the result of your TRUE wind angle-somewhere between 40-47 degrees (this is why the 80-90 degree tacking angle is "typical"-not 60-65 or so as you would expect based on AWA (apparent wind angle).
Same thing downwind: TWA of 155-160 is common in medium airs annd higher,
but you AWA could be 100-130 (some boats must reach higher than others to get good VMG DDW)-and your gybing angle is basewd on TWA-NOT AWA.
It may seem counterinuitive to those of us who learned with little or no instrumentation(like me), and worked with apparent wind because "that is what the boat feels", but you really get much more accurate, and apples to apples comparisons by using TRUE (if you have the guages to display the values). It was a big change in thinking for me, but once I got it through my skull, it makes more sense.
Sidebar to this is the fact that when you are trying to track wnd shifts (for example to know which tack or gybe is favored, or "closer" in heading to your destination), you need to work with TRUE wind direction and compass heading.
Anyway, this is the reason performance claims, and other comparitive data are generally expressed in terms of TWA, TWS, etc.
Is that horse dead yet? Someone check..
Cheers!
S
D'oohhh! Thanks Guy-that is a Polar chart. There is usually a table, or spreadsheet format as well when you get these.
It is also true that they are usually calculated for both True and Apparent wind speeds and awind angles, but I would differ on the value of the apparent wind data-Apparent wind it is quite a bit less accurate in that the apparent wind angle changes significantly as you accelerate, slow down, etc. If you hit a big wave, and slow down, the apparent wind speed slows and moves aft-putting you on a broader reach with less wind-if these were actual changes in woind speed and direction they would be of more value-but in fact they are quick and momentary, but will indicate better or worse than you can really expect from your boat.
Another problem is with upwind sailing (and downwind gybing). Although you may be sailing at 28-35 degrees or so to the apparent wind (upwind), your tacking angle (difference in compass heading from one tack to the next) is the result of your TRUE wind angle-somewhere between 40-47 degrees (this is why the 80-90 degree tacking angle is "typical"-not 60-65 or so as you would expect based on AWA (apparent wind angle).
Same thing downwind: TWA of 155-160 is common in medium airs annd higher,
but you AWA could be 100-130 (some boats must reach higher than others to get good VMG DDW)-and your gybing angle is basewd on TWA-NOT AWA.
It may seem counterinuitive to those of us who learned with little or no instrumentation(like me), and worked with apparent wind because "that is what the boat feels", but you really get much more accurate, and apples to apples comparisons by using TRUE (if you have the guages to display the values). It was a big change in thinking for me, but once I got it through my skull, it makes more sense.
Sidebar to this is the fact that when you are trying to track wnd shifts (for example to know which tack or gybe is favored, or "closer" in heading to your destination), you need to work with TRUE wind direction and compass heading.
Anyway, this is the reason performance claims, and other comparitive data are generally expressed in terms of TWA, TWS, etc.
Is that horse dead yet? Someone check..
Cheers!
S
Kevlarpirate
Member II
Thanks for the info
Thanks to both of you , I was sailing this weekend and came back to all this info!! Guy, the bump in the 10? KT line is the math prob you mentioned?
Anyway, the new double head rig is a big winner, I was surprised at it's power in the light air we were sailing and that the helm was very balanced.
I was also running my 5 full batten max roach main, Which I'm sure helped
My headsail was onky a 85% Yankee, very high clew, the big jibtop would have made 100% of the 6KTS VTW we were in, next week , more practice.
.Now all I need is a few bodies to help out! Anyway , great info , Thanks,
David
#12, ex Warlock
Thanks to both of you , I was sailing this weekend and came back to all this info!! Guy, the bump in the 10? KT line is the math prob you mentioned?
Anyway, the new double head rig is a big winner, I was surprised at it's power in the light air we were sailing and that the helm was very balanced.
I was also running my 5 full batten max roach main, Which I'm sure helped
My headsail was onky a 85% Yankee, very high clew, the big jibtop would have made 100% of the 6KTS VTW we were in, next week , more practice.
.Now all I need is a few bodies to help out! Anyway , great info , Thanks,
David
#12, ex Warlock