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Jackdaw

iPad polar generation app.. Tool or toy?

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There is a polar generating app available for the iPad.. From respected sailing software company KND SailingPerformance.

 

http://www.sailingperformance.com/iPolar.html

 

Says it generates accurate polars for non-extreme monohulls. But it ONLY asks for LOA and upwind and downwind sail area? LWL optional? Doesn't need displacement? Draft? Beam? I figure it assumes optimal foils but it still seems way to generic to be actually useful to me. Other thoughts? It's cheap I suppose but as Bob & Doug said, 'ten bucks is ten bucks'.

 

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I would love to hear if this program works or for that matter if anyone knows of another similar program out there that works. I have posted polars for just over 100 boats HERE so if anyone gets the program they can compare to the published numbers. I have dimensions for thousands of boats from several data bases HERE. Maybe the required dimensions are listed.

 

Allen

L-36.com

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This app might provide a good starting point for boats that don't have polars floating about on the internet.

 

for ~$275, you can get the US Sailing performance package from Jim Teeters, and for most boats that's a lot better than a starting point.

 

I use Expedition for refining polars, and the main issue there, is that you need a really good instrument system, with at least BSP, TWS and TWD working very well. In my experience, most boats don't have good enough instruments, or they are not calibrated well enough, to do much improvement over the Performance Package polars.

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This app is pathetic. I thought that for $10, I'd could risk that and find out. I tried it and loaded the dimensions of a boat for which I have the US Sailing polars. All it could do was produce downwind polars and even those weren't close.

A waste of time.

 

EDIT: if you can get a wifi instrument feed, iRegatta can build polars by logging your actual performance. They'll only be as perfect as your perfect performance !! :D

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This app is pathetic. I thought that for $10, I'd could risk that and find out. I tried it and loaded the dimensions of a boat for which I have the US Sailing polars. All it could do was produce downwind polars and even those weren't close.

A waste of time.

 

EDIT: if you can get a wifi instrument feed, iRegatta can build polars by logging your actual performance. They'll only be as perfect as your perfect performance !! :D/>

 

Won,

 

Hope I didn't goad you into that!! ;-)

 

It seemed to have to be a joke, ANY boats with the same LOA and sail area would generate the same polars and clearly that's wrong.

 

We have decent polars for both our boats (from the designers) but are planning to fine tune with iRegatta in the spring.

 

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Jack, no problem, I was interested to see it for myself :lol: and I'll stick with iRegatta and a wifi mux.

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I would love to hear if this program works or for that matter if anyone knows of another similar program out there that works. I have posted polars for just over 100 boats HERE so if anyone gets the program they can compare to the published numbers. I have dimensions for thousands of boats from several data bases HERE. Maybe the required dimensions are listed.

 

Allen

L-36.com

Fantastic website thx

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I would love to hear if this program works or for that matter if anyone knows of another similar program out there that works. I have posted polars for just over 100 boats HERE so if anyone gets the program they can compare to the published numbers. I have dimensions for thousands of boats from several data bases HERE. Maybe the required dimensions are listed.

 

Allen

L-36.com

Fantastic website thx

 

Thanks!

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I am new here, so hello everybody.

 

I purchased this app, very disappointing...

In fact, I think there is too few parameters taken into account.

I generated my boat's polars and it is way different from the ones provided by the boat designer.

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Hi there. I have also pourchased the app for my First31.7 I have to say that the results looks very good. The error compared to the ORC VPP is less than 5%. The reason I decided to use it is to investigate the use of various sailsets particularly while cruising when I dont want to use kites above 15kts TWS. Then I can have proper polars for my routing.

 

Cheers.

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While following the team we work with (Bella, Quantum and Ran) racing in Key West today I came across this thread discussing our iPolar.

 

So... Tool or Toy? Well it all depends!

If you are fighting for the podium in world class events, it's definitely a toy. You can still work with us if you please (like Groupama, Camper, BellaMente, Alegre, Quantum Racing, Ran, MACIF...) but timing and budgets will be slightly larger than the 10s/9.99€ iPolar... A full VPP takes a couple of days to run using our existing aero libraries, if you want your own aero, budget a couple of weeks of extra work and a hop to the Auckland wind tunnel...

 

If you are a cruiser or a club racer, then you might consider it since it can help you get started or enhance your performance program and use routing software. More of a tool then.

 

How come a VPP can work with so little input?

iPOlar is operating on a set of 81 proper VPPs. These VPPs have been run with a set of yachts we have designed. These boat are not aimed at replicating any existing model but to cover the production boats range in terms of power/displacement and length/displacement ratios. As a consequence, we have designed 3 yachts @ 9m, 12m and 15m representing comfortable cruiser, a standard cruiser and a cruiser racer. For each of these boats we have defined 3 sails area for Main+Jib, Main+Kite & Main+A-Kite (I mean 3 sails area for each sailset). Afterwards, we interpolate on L, DSP and SA and the results are not to bad.

 

How do we know it's good or bad?

We have retrieved the ORC international certificates of yachts ranging from a First 300 Spirit to a X50 going through some Oceanis, J Boats... The average error on our 17 yachts VPPs is 2% (averaging on the full TWS/TWA grid). The peak errors are usually below 10%. Here are a couple of examples:

Hunter32 Avg. Err 0% Std Dev 4%

First 36.7 Avg. Err -1% Std Dev 1%

J111 Avg. Err 0% Std Dev 5%

Swan 44 Avg. Err 2% Std Dev 2%

Yachts whose parameters are away from the production range (pure racers like TP52, Class40...) or with LOA above 65ft or below 24ft will yield much larger error levels as the tool is not covering their power/displacement ratios.

 

Why not just getting a polar from the web?

Actually that's a good idea. iPolar is still there for the ones who cant find their boat or need a bit more versatile tool:

iPolar produces targets for each sailset while VPPs usually gives you only the best sailset polar. That allows to do routing not using kites above a threshold TWS like CruiserRacer explains it here above One can also get an idea of sensitivities of sail area on the performance when considering new sails...

Club Racers, will probably want to combine this tool which is a base polar generator (and can be tweaked as much as you want!) to performance apps like iRegatta.

 

 

Dimitri.

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While following the team we work with (Bella, Quantum and Ran) racing in Key West today I came across this thread discussing our iPolar.

 

So... Tool or Toy? Well it all depends!

If you are fighting for the podium in world class events, it's definitely a toy. You can still work with us if you please (like Groupama, Camper, BellaMente, Alegre, Quantum Racing, Ran, MACIF...) but timing and budgets will be slightly larger than the 10s/9.99€ iPolar... A full VPP takes a couple of days to run using our existing aero libraries, if you want your own aero, budget a couple of weeks of extra work and a hop to the Auckland wind tunnel...

 

If you are a cruiser or a club racer, then you might consider it since it can help you get started or enhance your performance program and use routing software. More of a tool then.

 

How come a VPP can work with so little input?

iPOlar is operating on a set of 81 proper VPPs. These VPPs have been run with a set of yachts we have designed. These boat are not aimed at replicating any existing model but to cover the production boats range in terms of power/displacement and length/displacement ratios. As a consequence, we have designed 3 yachts @ 9m, 12m and 15m representing comfortable cruiser, a standard cruiser and a cruiser racer. For each of these boats we have defined 3 sails area for Main+Jib, Main+Kite & Main+A-Kite (I mean 3 sails area for each sailset). Afterwards, we interpolate on L, DSP and SA and the results are not to bad.

 

How do we know it's good or bad?

We have retrieved the ORC international certificates of yachts ranging from a First 300 Spirit to a X50 going through some Oceanis, J Boats... The average error on our 17 yachts VPPs is 2% (averaging on the full TWS/TWA grid). The peak errors are usually below 10%. Here are a couple of examples:

Hunter32 Avg. Err 0% Std Dev 4%

First 36.7 Avg. Err -1% Std Dev 1%

J111 Avg. Err 0% Std Dev 5%

Swan 44 Avg. Err 2% Std Dev 2%

Yachts whose parameters are away from the production range (pure racers like TP52, Class40...) or with LOA above 65ft or below 24ft will yield much larger error levels as the tool is not covering their power/displacement ratios.

 

Why not just getting a polar from the web?

Actually that's a good idea. iPolar is still there for the ones who cant find their boat or need a bit more versatile tool:

iPolar produces targets for each sailset while VPPs usually gives you only the best sailset polar. That allows to do routing not using kites above a threshold TWS like CruiserRacer explains it here above One can also get an idea of sensitivities of sail area on the performance when considering new sails...

Club Racers, will probably want to combine this tool which is a base polar generator (and can be tweaked as much as you want!) to performance apps like iRegatta.

 

 

Dimitri.

 

Dimitri,

Thank you for your detailed explanation. Seems more to it than first meets the eye.

For comparison, would you be willing to post some samples of overlayed images of your polars on VPP generated ones?

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Dimitri,

Thank you for your detailed explanation. Seems more to it than first meets the eye.

For comparison, would you be willing to post some samples of overlayed images of your polars on VPP generated ones?

yes a good explanation and a useful idea to allow a change of spinnaker. When switching between asymm and symm I couldn't see any substantial change in the reaching angles on a boat that is similar to the B36.7 in terms of performance and characteristics.

 

It might be an idea to put more of an explanation in iTunes of the range of ratios that the tool was designed for, to better manage expectations.

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Glad to see the explanations were welcome,we'll try and make sure the website and iTunes convey a bit more info of that nature.

 

Now onto some comparisons with ORC VPP certificates so you can make yourself an idea of the deltas.

 

X37 iPolar

iPolar TWA/TWS 6 8 10 12 14 16 20 50 5.1 6.18 6.86 7.28 7.47 7.55 7.6 55 5.42 6.49 7.13 7.53 7.71 7.8 7.83 60 5.65 6.69 7.29 7.69 7.9 7.99 8.03 75 6 6.95 7.51 7.9 8.23 8.47 8.57 90 6.22 7.27 7.85 7.82 8.12 8.44 9.04 110 5.7 6.88 7.58 8.06 8.49 8.95 9.51 120 5.47 6.67 7.41 7.9 8.3 8.71 9.78 135 4.79 6.02 6.89 7.47 7.88 8.25 9.03 150 4.11 5.16 6.09 6.83 7.4 7.85 8.63

 

 

Delta to ORC certif.

Error (kts) 52° -0.06 -0.04 -0.01 0.09 0.11 0.09 0.04 60° -0.21 -0.17 -0.04 0.09 0.14 0.13 0.06 75° -0.47 -0.35 -0.25 -0.08 0.08 0.17 0.11 90° -0.36 -0.07 0.06 -0.37 -0.41 -0.25 0.12 110° -0.35 -0.14 -0.11 -0.12 -0.15 -0.07 0.04 120° -0.25 -0.19 -0.07 -0.03 -0.07 -0.11 0.01 135° -0.16 -0.13 -0.09 -0.05 -0.07 -0.12 -0.24 150° -0.01 -0.05 -0.15 -0.14 -0.08 -0.05 -0.06

 

 

Same in %

Error (%) -1% -1% 0% 1% 1% 1% 0% -4% -2% -1% 1% 2% 2% 1% -7% -5% -3% -1% 1% 2% 1% -5% -1% 1% -5% -5% -3% 1% -6% -2% -1% -1% -2% -1% 0% -4% -3% -1% 0% -1% -1% 0% -3% -2% -1% -1% -1% -1% -3% 0% -1% -2% -2% -1% -1% -1%

 

 

First40.7

iPolar TWA/TWS 6 8 10 12 14 16 20 50 5.4 6.5 7.2 7.5 7.7 7.8 7.8 55 5.7 6.8 7.4 7.8 8.0 8.1 8.1 60 5.9 7.0 7.6 8.0 8.2 8.2 8.3 75 6.3 7.2 7.8 8.2 8.6 8.8 8.8 90 6.3 7.2 7.8 8.1 8.5 8.9 9.4 110 5.7 6.9 7.7 8.2 8.6 9.1 9.8 120 5.4 6.7 7.5 8.0 8.4 8.8 9.9 135 4.7 6.0 6.9 7.5 8.0 8.4 9.1 150 4.1 5.1 6.1 6.9 7.5 7.9 8.7

 

 

Delta ORC certif

Erreur (kts) 52° 0.18 0.20 0.30 0.36 0.34 0.31 0.22 60° 0.17 0.19 0.23 0.33 0.33 0.30 0.20 75° 0.15 0.18 0.18 0.21 0.30 0.35 0.27 90° 0.14 0.17 0.16 0.13 0.11 0.16 0.37 110° -0.06 0.00 0.03 0.02 0.00 0.11 0.52 120° -0.09 -0.03 0.00 0.01 -0.05 -0.09 0.16 135° -0.15 -0.11 -0.05 -0.03 -0.06 -0.12 -0.23 150° -0.02 -0.05 -0.10 -0.08 -0.06 -0.04 -0.06

 

 

Error (%) 3% 3% 4% 5% 5% 4% 3% 3% 3% 3% 4% 4% 4% 2% 2% 3% 2% 3% 4% 4% 3% 2% 2% 2% 2% 1% 2% 4% -1% 0% 0% 0% 0% 1% 6% -2% 0% 0% 0% -1% -1% 2% -3% -2% -1% 0% -1% -1% -2% 0% -1% -2% -1% -1% -1% -1%

 

 

SUN FAST 32

 

iPolar TWA/TWS 6 8 10 12 14 16 20 50 4.2 5.2 5.8 6.3 6.6 6.7 6.8 55 4.5 5.5 6.1 6.5 6.8 6.9 7.0 60 4.7 5.7 6.2 6.6 6.9 7.1 7.2 75 5.0 5.9 6.5 6.8 7.1 7.3 7.7 90 4.9 5.9 6.4 6.8 7.0 7.2 7.7 110 4.7 5.8 6.4 6.8 7.1 7.5 8.2 120 4.5 5.6 6.2 6.7 7.0 7.3 8.0 135 4.0 5.0 5.8 6.3 6.7 7.0 7.6 150 3.4 4.3 5.1 5.8 6.3 6.7 7.3

 

 

Erreur (kts) 52° 0.1 0.11 0.195 0.295 0.365 0.375 0.325 60° 0.06 0.11 0.21 0.28 0.35 0.4 0.36 75° 0.03 0.13 0.22 0.26 0.3 0.34 0.4 90° 0.02 0.09 0.08 0.08 0.11 0.19 0.3 110° -0.12 -0.06 -0.01 0.02 0.03 0.04 0.31 120° -0.15 -0.13 -0.07 -0.02 -0.02 -0.02 0.08 135° -0.17 -0.24 -0.16 -0.11 -0.09 -0.09 -0.11 150° -0.12 -0.22 -0.27 -0.2 -0.13 -0.08 -0.07

 

 

Erreur (%) 2% 2% 3% 5% 6% 6% 5% 1% 2% 3% 4% 5% 6% 5% 1% 2% 4% 4% 4% 5% 6% 0% 2% 1% 1% 2% 3% 4% -2% -1% 0% 0% 0% 1% 4% -3% -2% -1% 0% 0% 0% 1% -4% -5% -3% -2% -1% -1% -1% -3% -5% -5% -3% -2% -1% -1%

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Jack, no problem, I was interested to see it for myself :lol: and I'll stick with iRegatta and a wifi mux.

 

We're using iRegatta in stand-alone mode at the moment, but I'm in the process of shopping for an instrument package for the boat and want to add the wifi connectivity if possible. Any suggestions on instruments and/or wifi portals?

 

DJL

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This app might provide a good starting point for boats that don't have polars floating about on the internet.

 

for ~$275, you can get the US Sailing performance package from Jim Teeters, and for most boats that's a lot better than a starting point.

 

I use Expedition for refining polars, and the main issue there, is that you need a really good instrument system, with at least BSP, TWS and TWD working very well. In my experience, most boats don't have good enough instruments, or they are not calibrated well enough, to do much improvement over the Performance Package polars.

 

The problem with the US Sailing package is that you still have to have accurate measurements of your boat, which generally means getting it laser measured, which depending on the size of your boat may double (or more) the price of the package.

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NMEA 801, 2K, and seatalk compatibility.

 

http://www.dmkyacht.com/specifications

 

Sadly it does not TRANSLATE... so if data (kie wind and speed) is seatalk it will broadcast it as seatalk... if your app (like iRegatta) needs nmea you still need a translator. Grrrr...

Shipmodul Miniplex2 Wi and Brookhouse both have SeaTalk ports that translate to NMEA 0183

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This app might provide a good starting point for boats that don't have polars floating about on the internet.

 

for ~$275, you can get the US Sailing performance package from Jim Teeters, and for most boats that's a lot better than a starting point.

 

I use Expedition for refining polars, and the main issue there, is that you need a really good instrument system, with at least BSP, TWS and TWD working very well. In my experience, most boats don't have good enough instruments, or they are not calibrated well enough, to do much improvement over the Performance Package polars.

 

The problem with the US Sailing package is that you still have to have accurate measurements of your boat, which generally means getting it laser measured, which depending on the size of your boat may double (or more) the price of the package.

 

Ryley,

This is precisely why we have been asked to developed a simple tool like iPolar! Most cruisers and club racers do not have access to their yacht hull surface nor VCG to be able to use an advanced VPP.

 

 

 

US7070

You are right. There are packages available for performance analysis (including ours!). However,

to be able to do anything valuable with sailing data, one needs to make sure the calibration is good. And that is definitely not the case 99% of the time on a cruising or cruiser racer. Therefore trying to define VMG up and down targets is not an easy task since 1° TWA error is roughly 1% error on the VMG upwind.

Now lets assume the calibration is good. There are still problems to tackle through filtering of the data. Two examples: 1) days with wind shear will alter significantly the port/stb behavior and you can easily 'inflate' your targets by a couple % if you dont filter those out. 2)transitions. the moment you get out of a puff, the performance increases significantly because of your boat inertia until it slows down. Therefore, looking at individual points (like 1s data) is not very meaningful and a filtering of stable conditions + averaging on larger time samples is requred.

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Hi Jackdaw

 

Great work above

 

Iam look at buying a cruiser / racer

Iam considering a Benny first 47.7

What's your thoughts?

Any other suggestions ??

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Hi Jackdaw

 

Great work above

 

Iam look at buying a cruiser / racer

Iam considering a Benny first 47.7

What's your thoughts?

Any other suggestions ??

You might get better replies posting this in the main Sailing anarchy forum or cruising anarchy. In any event, you could PM Cirdan who has an exceptionally well equipped First 47.7 that's sailed from Vancouver to Sydney, and back, including a Sydney Hobart, and numerous Vic-Maui races (and a win in 2010). There is nothing he doesn't know about that boat.

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Hi Jackdaw

 

Great work above

 

Iam look at buying a cruiser / racer

Iam considering a Benny first 47.7

What's your thoughts?

Any other suggestions ??

You might get better replies posting this in the main Sailing anarchy forum or cruising anarchy. In any event, you could PM Cirdan who has an exceptionally well equipped First 47.7 that's sailed from Vancouver to Sydney, and back, including a Sydney Hobart, and numerous Vic-Maui races (and a win in 2010). There is nothing he doesn't know about that boat.

 

I concur. PM Cirdan.

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for ~$275, you can get the US Sailing performance package from Jim Teeters, and for most boats that's a lot better than a starting point.

 

As someone pointed out, you need accurate measurements of your hull and rig, including weight. That said, Jim has a pretty good database with many, many boats. Unless you have a very odd boat he probably has some good measurement data. If not, have the boat measured. If you're spending for an instrument package that is capable of using polar data, the cost of measuring and the polars is probably less than the cost of one display.

 

Properly calibrated instruments are key to getting this to work. It takes time to calibrate, but if you don't do it, the instruments won't help you.

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Toy. The most frustrating part is that Weather4D Pro requires iPolar for the polar inputs, but you can't edit the iPolar table, even if you already know your Polars. Grrrrr.... Stupid.

 

I had to make our jib genoa sized and our spinnaker about 200 sq feet smaller to get close to our actual numbers.

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Yes... totally unrealistic for the boat I tried.... C&C 110 sprit verson with asymm. It is way under on the upwind targets we actually experience, and the shape of the downwind targets seems more suited for a symmetrical. even though I selected asymm. I will use other tools to refine them. On the next round of distance races where I can get lots of samples data, I will be using Expedition to do this. Anyhooo... it was a giggle trying this iApp :)

.

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This app is pathetic. I thought that for $10, I'd could risk that and find out. I tried it and loaded the dimensions of a boat for which I have the US Sailing polars. All it could do was produce downwind polars and even those weren't close.

A waste of time.

 

EDIT: if you can get a wifi instrument feed, iRegatta can build polars by logging your actual performance. They'll only be as perfect as your perfect performance !! :D

 

Have used the IRegatta polar generating program over the course of a recent regatta and I thought the info it produced was pretty good. Certainly started to generate some consistent results over the series.

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Vagabundoll,

 

You have a nice looking yacht but its characteristics (SA/DSP ratios, appendages...) would yield to significant loss of accuracy for iPolar which is based on a set of VPPs corresponding to modern production yachts.

 

Dimitrivlc - KND-SailingPerformance

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