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NZL51

Low cost, effective, tide and wind routing

38 posts in this topic

Hi Guys,

 

We are doing the fastnet in two weeks time. Currently we are doing our routing by running a wind routing using gribs on qtvlm and then consulting the admiralty tidal book to make a decision on where we should be going. its pretty rough.

 

We arent looking to spend a fortune so deckman is probably out, but does anyone have any suggestions for low cost software solutions that will account for wind and tide?

 

On another note what are the options for data logging software for windspeed awa bs etc for refining the polars we are currently using?

 

Any thoughts would be great

Cheers

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I think Great Circle offer a short-term license for their software.

 

http://www.greatcircle.be/

 

they also have an ipad app

 

as far as logging goes..., do you have an on-board PC connected to your instruments?

 

you need very well calibrated instruments if the logged data is to be useful for refining polars.

 

what kind of boat.., and what polars are you starting with?

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thanks i will check that out.

 

Yeh its all hooked up to a pc.

 

Current polars we found in a random iphone application someone downloaded.

 

The boat is a JPK 9.60 . Just wanted to validate the numbers really as the boat was set up for short handed sailing by the frenchies. Large sail crossovers to reduce changes. As such it is possible that the sail inventory is nothing like the one used to produce the polars, but we just dont know.

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well, i know there is an iphone app out there that will create polars based on a few input parameters.

 

it was discussed in a thread here some time ago.

 

i think some people got a result that at least approximated their "real" polars, and some didn't..

 

i think the author of the app said it works best for displacement cruiser-racers.

 

anyway, it's a starting point.., but if you ask around you might find that there are designer polars that would be better.

 

 

SA member Valis has a free program that will log NMEA instrument data

 

http://www.navmonpc.com/index.html

 

i haven't used it, but it looks like it will do what you need.

 

then, you could maybe edit the polar table in a text editor, or a spreadsheet program.

 

Expedition has a pretty good polar editing utility - but it sounds like you don't want to spend ~$1300

 

again - you need to calibrate your instruments before logging, or it won't be very useful.

 

what instruments do you have?

 

if you can get designer polars, i would probably just use them for routing - if it's really windy, with big waves etc., just slow them down a bit as they are probably for flat water.

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I made usable polars with some trial and error using ipolar on iPad.

Result can be easily exported to app weather4D Pro. (W4Dp)

In W4Dp you can import gribfiles and current data from several providers, also GreatCircle.

With W4Dp then you can do routing based on these variables. Result looks like this:

http://lh4.googleusercontent.com/-cukM24XQu4o/Ub9bI8SZR1I/AAAAAAAAIf0/Isv4A6UmwFo/s2048/IMAGE_DED61B04-8DA6-43FE-ADC1-9163E61018A8.PNG

Resulting route can be exported easily to for example iNavX.

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Just made a more specific example: fastnet route; Imoca60 polar (not mine ;-) ; current up to Penzance. Departure "NOW". Arrival thursday around 8:00AM

http://lh3.googleusercontent.com/-s9Qtj5uErQA/UfagXSmnpAI/AAAAAAAAIkA/vnHMB5Dy9GQ/s2048/IMAGE_5.jpeg

 

thanks for that. thats factoring in the currents to penzance? where did you source your tidal data?

 

is there a version of this that runs on windows?

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Tidal data through in-app W4Dp from Tide-Tech. Yes, currents only up to Penzance. The tide tech data is very detailed (large download) but segmented in areas. Other less detailed and less segmented current data is available, but for Channel not advisable.

All apps I mentioned are iPad, not Windows.

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the w4d app is the app is by the same guys who do the great circle software i linked above - so i guess that is the windows version of the app

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the w4d app is the app is by the same guys who do the great circle software i linked above - so i guess that is the windows version of the app

ah right i see, i installed the squid software to have a look. Seems simple enough though the accessible features are restricted.

it has a button that says "request a routing". does this mean the routing calculations arent performed locally on the machine? Being that we are relying on 3G to download new information this would be an issue when we get offshore.

I have emailed them to ask.

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the w4d app is the app is by the same guys who do the great circle software i linked above - so i guess that is the windows version of the app

ah right i see, i installed the squid software to have a look. Seems simple enough though the accessible features are restricted.

it has a button that says "request a routing". does this mean the routing calculations arent performed locally on the machine? Being that we are relying on 3G to download new information this would be an issue when we get offshore.

I have emailed them to ask.

 

i haven't used the software, so i don't know if routing is done locally or not

 

i have been looking for an excuse to play with it, so maybe i will do so in the next few days.

 

but, there may be an issue beyond the 3G..., if the routing is not done locally, it might be considered "outside assistance" under the RRS.

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Expedition can typically be demo'd for either 14 or 30 days..., as a fully operational program.

 

I suppose if you know now that you have no intention of buying it, it might be a bit offside to do so, but if there is a chance you would like it enough to buy it, then maybe it's ok...

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the w4d app is the app is by the same guys who do the great circle software i linked above - so i guess that is the windows version of the app

I don't think so: W4D is an app made by a Frenchman, great circle is Belgian. They do have some sort of cooperation though: GC acts as a data provider for W4D(p) trough Internet and thus 3G

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the w4d app is the app is by the same guys who do the great circle software i linked above - so i guess that is the windows version of the app

I don't think so: W4D is an app made by a Frenchman, great circle is Belgian. They do have some sort of cooperation though: GC acts as a data provider for W4D(p) trough Internet and thus 3G

 

 

ok - thanks..., i wasn't sure of the exact relationship

 

i see that on the great circle web site there is an asterisk indicating that purchase of a great circle subscription doesn't include the W4D app - just the data for the app.

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the w4d app is the app is by the same guys who do the great circle software i linked above - so i guess that is the windows version of the app

ah right i see, i installed the squid software to have a look. Seems simple enough though the accessible features are restricted.

it has a button that says "request a routing". does this mean the routing calculations arent performed locally on the machine? Being that we are relying on 3G to download new information this would be an issue when we get offshore.

I have emailed them to ask.

 

i haven't used the software, so i don't know if routing is done locally or not

 

i have been looking for an excuse to play with it, so maybe i will do so in the next few days.

 

but, there may be an issue beyond the 3G..., if the routing is not done locally, it might be considered "outside assistance" under the RRS.

Very good point.

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OpenCPN. Available for Windows, you can input Tide data (or use what comes with it), weather and polars for routing. Not sure the tides are taken into account on the routing though you'd have to look at their documentation.

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OpenCPN. Available for Windows, you can input Tide data (or use what comes with it), weather and polars for routing. Not sure the tides are taken into account on the routing though you'd have to look at their documentation.

 

OpenCpn routing is just importing the route as a kml file from Qtvlm.

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Reply from great circle,

 

the routing is done on their servers, so not an option for us.

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right quick brainstorm then, Can people throw the names of any and all programs that do current and wind routing at me?

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Expedition

Adrena

Deckman

SeaTrack

QtVlm - no currents i guess...

SailFast

possibly others too

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And weather 4D Pro

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Try Predictwind. Wind and Tide and choose from a range of pre loaded polars or upload your own. This is what they suggest if you left now for a Bendyslow 40.7

 

http://www.predictwind.com

I am pretty sure that predict wind routing is not done locally so you have the same issue of outside assistance as discussed above for great circle

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Yacht Racing Rules

Is it legal to use PredictWind whilst racing?

Rule 41 of the Racing Rules of Sailing (RRS) state "A boat shall not receive help from any outside source, except ..." , and the exception 41 © which states "help in the form of information freely available to all boats;"

The interpretation given for the words “freely available” as used in RRS 41© was "free of cost" for all competitors. Therefore during racing, competitors are limited to only using the free package of PredictWind. Before the start of the race competitors may use the PredictWind paid packages.

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he said he wants to do routing during the race.

 

that's typically how it is done - as new WX becomes available, you re run the routing from your position at that time.

 

WX is available 4 times a day - depending on what models you are using

 

if i understand correctly, the predict wind routing is always a paid service, it is not available in the free package

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Try http://www.bluewaterracing.com/, $10 donation is nice

 

Having read their forums i gather that although the software will display tidal data that is in a grib format it doesnt use it in its routing calculations yet. I will install and look as to whether this is an improvement on qtVLM

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Try http://www.bluewaterracing.com/, $10 donation is nice

 

Having read their forums i gather that although the software will display tidal data that is in a grib format it doesnt use it in its routing calculations yet. I will install and look as to whether this is an improvement on qtVLM

 

qtVlm do include currents in its routing calculations if a currents grib is loaded (you can load a regular winds grib plus a currents grib at the same time).

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Try http://www.bluewaterracing.com/, $10 donation is nice

 

Having read their forums i gather that although the software will display tidal data that is in a grib format it doesnt use it in its routing calculations yet. I will install and look as to whether this is an improvement on qtVLM

 

qtVlm do include currents in its routing calculations if a currents grib is loaded (you can load a regular winds grib plus a currents grib at the same time).

By any chance are you the same maitai i saw on the cruiser forums website?

 

Thats excellent news is there anything special i have to do to make it work?

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You just need to find and load a grib containing currents data. If this grib contains both winds and currents information (which is quite rare) then you can load it as usual, if it contains only currents data then you need to load it on top of a regular winds grib (grib->open a currents grib). Some currents grib are not supported yet in this version (the next version due soon will support some more).

 

(and yes I am the same maitai ;) )

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Thanks Maitai,

 

can you recommend any sources for the current data that will work with qtVLM? We need it for the English channel and irish sea.

Ideally we dont want to have to take out a subscription to a provider.

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If you look at the Vendee thread - Estar was using an free package for routing all the boats. I think it was Adrena. Send him a PM.

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Last weekend did the Brisbane to Keppel and did the whole thing with Weather4d pro and Tidetech. Finished 2nd overall. Some top line program's in the race including Wild Oats, Black Jack etc. Can't complain at that.

 

You need a nav package to make up GPX files as well. We used i sailor, but inavx would be preferable

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