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Old 30-11-2012, 10:15   #226
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Hi maitai,
On the official vendee globe website i found this news

Following the latest readings by specialised companies, the ice is positionned quite high on the Vendée Globe route. The Kerguelen gate (50°00 S / 040°00 E - 050°00 E) is therefore replaced by the Crozet gate (39°00 S / 042° 00 E - 050° 00 E). As a consequence, the complete race route will be 300 nautical miles longer. CLS (Collecte localisation satellites) will share more information on that topic in their press conference on Friday afternoon.

Will this be the same in VLM
Hartmut
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Old 30-11-2012, 10:50   #227
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Re: VENDÉE GLOBE round the world race

No because the first boat of the fleet has already passed 10W, so according to our ICs we cannot move the gate anymore.
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Old 30-11-2012, 10:56   #228
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thanks for that information, because with that change the strategie would have been totaly different.
So now we can stay on our old strategie
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Old 30-11-2012, 14:56   #229
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Re: VENDÉE GLOBE round the world race

Okay I finally got a Routing that would show an "Reverse Isochrone" what is different now? I don't know why it worked this time. The "Show colored TWS" was also checked. Now that I have checked to "Reverse the Isochrone" I cannot uncheck it, that function is greyed out. I can only show or not show both the isochrone and the reverse isochrone.

How do I think about the "weather risks" of a Reverse Isochrone?

1. Do the wider distances between lines show the faster route towards the destination because they are the paths that have the most wind?
2. Where there is change and the wind drops along a line or ridge, the isochrones change direction and become closer together, the wind has dropped and changed direction, this might be a place to avoid depending on where you want to go.
3. Are there any general rules about Reverse Isochrone?

See attached example, I think the grey blob is from "Showing colored TWS" at the same time. Before I created the Routing I screwed around with the <Advanced Tab>
1. Divergence to 58% (which is what?)
2. Forecast Modification checked Use this Scenerio, then
3. Setting the date and time for the change.
4. Setting Forecast wind to 90% of the forecast
5. Offset grib forecast 1 hour

Was this the reason the Reverse Isochrone worked?
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Old 30-11-2012, 18:05   #230
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Re: VENDÉE GLOBE round the world race

Here's another example of an Reverse Isochrone which shows pretty well what Maitai has talked about "Weather Risk" I think.

You see the old "black" <Routing> that has been converted to a <Route> and has very very recently been optimized and simplified to death multiple times. The black Routing was forced to follow the Gates by use of multiple <Pivots> which set a special waypoint that does not move (I believe). Thus this black Route represents a melding of an old optimal route before the weather changed and recent optimizations which improve the ETA, but keep the special waypoints in place. (you can delete them as they are visible).

The "Pink" <Routing> has not been converted to a route and was just created, so it has not been simplified and optimized further in <Route> form. Notice that it follows the grey area which is defined by the intersection of the reversed isochrone lines (one node on each side defines the extent of the grey area). This grey area defines a theoretical area for reasonable routes. Note the risky thin grey area just after the WP4 long vertical gate. There is high risk in that area that the winds and weather will change from what is predicted and because there is not much leeway on this narrow "bridge" hitting it right is important. There are a series of 5 screens showing the time with a darker highlighted isochrone moving across the southern ocean. Note the intersection width of the same isochrone / reverse isochrone varies. This diagram corresponds to the amount of "curve" (tight or loose) that a isochrone has. "Tigher" radius is more risky from a weather standpoint, a little change affects the angle and speed of wind more than on a gradually curved isochrone.
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Old 30-11-2012, 18:14   #231
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Re: VENDÉE GLOBE round the world race

Hypothesis: The routing should stay within the greyed reversed isochrone area, generally, even if there is a more direct routing available that goes outside the grey area, in order to honor a gate (for example). Why? because the direct route will take the boat in risky weather areas and it would be less risky to chart a route to stay within the grey area. This route will take longer, but is not as weather risky.

This is a hypothesis that I'll be testing.
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Old 30-11-2012, 18:24   #232
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Re: VENDÉE GLOBE round the world race

I now think that hypothesis is wrong.
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Old 30-11-2012, 18:40   #233
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Re: VENDÉE GLOBE round the world race

Here is a screenshot with the underlying "Pink" <Routing> and greyed area from the reversed isochrone. Over that is a "Black" Routing which forces the boat to honor Gate WP3 with a Pivot Waypoint (Right click, create a new waypoint), the natural optimized route then gradually works its way back down to the greyed areas which are the preferred area, missing the other required gates.

To make this more complicated, just wait long enough and all this will change as the Grib predictions change in the next update! - So maybe it makes sense to start reading the Pilot Charts!
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Old 30-11-2012, 18:50   #234
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Re: VENDÉE GLOBE round the world race

Here the Routing is forced to honor the next Gate WP5 with a Right click > Create Pivot point and new isochrones are created, starting at that Pivot point.

The preferred route then tends towards the grey areas of the reversed isochrones. It appears to naturally go north of Gate WP7 in West Australia

There are now special Pivot waypoints set at Gates WP3 and WP5 that will not move even when the route is converted to a <Route> and optimized.
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Old 30-11-2012, 18:55   #235
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Re: VENDÉE GLOBE round the world race

This screen shot applies to above message.
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Old 30-11-2012, 19:05   #236
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Re: VENDÉE GLOBE round the world race

Here's a snapshot of that <Routing> converted to a <Route> then simplified and optimized several times. The route has been turned thick Orange. It is outside of the greyed Reversed Isochrone area for the first half and within it in the second half where there have been no path forced Pivot points.
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Old 01-12-2012, 00:51   #237
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Re: VENDÉE GLOBE round the world race

Hello maitai

i found a minor bug in VLM.
1. select the language German by clicking on the flag
2. select map (Karte)
3. select any choice of boat an click on apply (bestätigen)
--> the selection didnt work
The same sequence in english is ok

Hartmut
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Old 01-12-2012, 00:55   #238
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Re: VENDÉE GLOBE round the world race

So the first boat in VLM had passed the AtlanticGate and are now heading south. Boat 3925 (chboing) currently on #5 has missed the western point of this gate.
maitai is there a notification to such boats that they have missed such a gate.
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Old 01-12-2012, 01:34   #239
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Re: VENDÉE GLOBE round the world race

chboing has realised his mistake and turnd 180 degrees back to the AtlanticGate
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Old 01-12-2012, 01:35   #240
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Re: VENDÉE GLOBE round the world race

Thanks for the bug report. It's not in qtVlm it's at VLM webpage is it?

There is no motification if you miss a gate (such as an email). Especially in this case it's an ice gate so the only thing required is to be seen at least once at the north of it (it's not compulsory to cross it). btw chboing has realized his mistake and is heading north again.
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