Zezo forum:

Post by zezo | 2014-01-27 | 17:17:37

I've added the ice zones to the Sodebo race. The french forum says boat speed is decreased by 70% in those areas.

I'm extracting the zone info from the VR image files, so there may be small differences, depending on the actual resolution of the data VR uses.

The forum also says the ice charts will be updated now and then, but the image files are dated 18-Oct-2013 now. Please let me know if you see a change or read about it somewhere.

33 Comments

Post by zezo | 2014-01-27 | 17:30:37

The ice zones are not directly visible in the chart, but can be detected by anomalies in the isochrones. This is the first zone along my way, around 46S 10W.

Edit: Fixed that.

Post by ctr | 2014-01-28 | 09:19:19

fantastic great wonderful

Post by zezo | 2014-01-28 | 13:10:11

Got the 'bergs in the chart too

Post by din0 | 2014-01-28 | 13:26:12

Many thanks. I see you've added iceberg images now.
Have you set extracting from VR image files automatically? Or you have to change it once it changes in VR. I read somwhere in fr forum that, once we are closer to iceberg zone, the ice fields will be updated daily.

Post by zezo | 2014-01-28 | 13:32:39

The conversion happens to be possible with single unix command line usnig ImageMagick:

convert -threshold 80% +append map*.png pnm:- | egrep -a -v '^(P4|# CREAT|1024)' > ice.bin

where map*png are 4 files downloaded from the game server. That can be easily scheduled to run few times / day.

Post by WaterHammer | 2014-01-28 | 18:17:08

You are genious!

Post by zezo | 2014-01-28 | 18:49:12

It's the authors of ImageMagic, a image manipulation command line tool which actually predates PhotoShop.

And then the UNIX user mindset. It would take less than 50 lines of code to do the same thing using some image manipulation library, but why bother if there is system tool for that already.

Post by PalaEksa | 2014-01-29 | 12:51:56

Hi
Fantastic job with the icebergs ! Thanks a lot !
BTW, did you integrate the fact that the speed will be proportionnally decreased after 60�S ? ( I think I've read that it will be a percentage, like 10% between 60 and 61�S, 20% between 61 and 62�S, and so on ) ?

Thanks again.

Post by zezo | 2014-01-29 | 12:59:14

In previous races there has been hard 50% speed drop at 60�S, and I've coded it that way now.

If you have reliable source about a new penalty system I can integrate it as well.

In reality it should not really matter, because below 60�S you get on the wrong side of the low pressure systems most of the time and the router should avoid that even without a penalty.

Post by zezo | 2014-01-29 | 13:16:27

Just found one possible exception to my own statement above.

Going below 60 could be an option on the long leg between Australia and Cape Horn. To make things even more complicated there is an iceberg zone there right now exactly north of the red line.

Post by ctr | 2014-01-29 | 16:11:51

hello
Here is a answer (in french) from the forum to the new penalty of 60�S :

D�s que l�on atteint les 60�, la vitesse est diminu�e de 25%, puis ralentissement progressif lin�aire � chaque �� jusqu�� 61� pour atteindre une diminution de 75 % (1/4 de la vitesse initiale).
Exemple pour une vitesse de 20 n�uds :
59� 59� 59�� : 20 n�uds ( - 0%)
60� 00� 00�� : 15 n�uds ( - 25%)
60� 06� 00�� : 14 n�uds ( - 30%)
60� 12� 00�� : 13 n�uds ( - 35%)
60� 18� 00�� : 12 n�uds ( - 40%)
60� 24� 00�� : 11 n�uds ( - 45%)
60� 30� 00�� : 10 n�uds ( - 50%)
60� 36� 00�� : 9 n�uds ( - 55%)
60� 42� 00�� : 8 n�uds ( - 60%)
60� 48� 00�� : 7 n�uds ( - 65%)
60� 54� 00�� : 6 n�uds ( - 70%)
61� 00� 00�� : 5 n�uds ( - 75%)
au-del� de 61� : 5 n�uds ( - 75%)

Attention, la vitesse affich�e ne pr�sente aucun changement et ne prend pas en compte cette baisse, mais en r�alit� le bateau est bel et bien ralenti de 25 � 75%.

Post by zezo | 2014-01-29 | 16:15:31

Thanks. I get the idea. Will implement it if/when needed.

Now the question is what happens if you are in an iceberg zone at 60� 30� - 10 knots or 3 knots.

Post by ctr | 2014-01-29 | 16:56:42

Logically I think the penalties are added together

Post by PalaEksa | 2014-01-29 | 19:26:15

Thank you CTR for having found these penalties. I knew they were written somewhere but I was unable to find them again, and I got no answer as usual from VR ...

Post by ctr | 2014-01-30 | 21:02:59

Thomas Coville ayant abandonn�, Virtual r�gatta ne recevra pas les coordonn�es des icebergs ainsi que leur �volution.

Les zones des glaces affich�es sur la carte resteront donc telles-quelles.

Post by zezo | 2014-01-30 | 21:22:16

Thanks. That zone at 60S/128.5W may be nasty. I was hoping it would move away a bit.

Post by ctr | 2014-01-30 | 21:40:20

It may be more interesting to go below 60 degrees in this area

Post by zezo | 2014-01-30 | 21:44:31

The low pressure systems run deeper there, the great circle is longer and much more South. May well be worth the few hours lost in the ice fied/below 60. One thing that is not clear is the resolution of the ice zones - Most of them look like 1x1 degree with 15% more and rounded corners, but some of them around Cape Horn are more like half degree circles.

Post by sudoeste | 2014-02-17 | 15:31:33

Hi Cvetan

Zezo is recomending me to end the day below 60� and has changed the recomended route through the icebergs in South Pacific, and is now sending us directly through the icebergs. Is your simulator allready considering the 70% speed penalty from going through the icebergs and the progresive penalty from descending below 60�?

Many thanks

SW

Post by zezo | 2014-02-17 | 15:50:17

The problem with crossing the icebergs at 54S is that the routing is done in 1-hour steps for the longer periods (> 2 days).

This means that one step skips half of the iceberg field and the expected penalty is reduced from 6 to 3 hours.

Going below the red line could be viable option indeed - you would have about 70% boat speed there.

Penalty will become more accurate when we are within 48 hours of the iceberg, and even more so within 24 hours.

BTW there has always been similar problem with jumping over small islands.

Post by sudoeste | 2014-02-17 | 21:39:20

Thanks for the explanation Cvetan. We have been fighting neck to neck since the brasilian coast, and zezo has been a great help. I didn't follow zezo's directions last night and fell behind you, but we still have a lot of sailing to do...

Post by sudoeste | 2014-02-19 | 12:47:51

Here we go... straight to the icebergs. I'm trusting you with my life and the safety of my boat, but I fear it will take us a bit longer to cross than anticipated by zezo, even in 24 hr resolution. Anyway, you are just by my side so if I sink you will be there to rescue me. Eheheh!

Post by zezo | 2014-02-19 | 12:49:52

Yes, probably about one hour longer, but that remains to be seen. There seems to be a peripheral area where speed reduction is only 50%, bit its exact size is unknown. We'll learn soon ;-)

P.S. It looks like the real issue is not the iceberg zone itself but the small high pressure system lurking 24 hours ahead. It will affect one of the 3 possible routes.

Post by Gwellan | 2014-02-19 | 14:22:05

I'm in an iceberg zone and my speed is reduced by 50%.
It displays 18.2k on my screen but when a friend look at my boat he can see my speed at 9.1k.

Post by zezo | 2014-02-19 | 14:26:11

I saw two boats in the same state today and checked the forum. There is a post in the french version about 50% penalty in the periphery of the ice field.

The game engine view of your speed at the last update should be visible in the green info box below the "Boat name" input.

Post by sudoeste | 2014-02-19 | 15:43:50

Haha! zezo is now beeing more cautious and is sending us over the top of the iceberg zone. Did you make any changes?

Post by zezo | 2014-02-19 | 15:53:14

Nope. It was mostly the noon GFS update, possibly combined with the precision going down from 20 to 10 minutes as we get closer to the zone.

Post by sudoeste | 2014-02-19 | 16:39:08

You, on the other hand, are keeping to the old strategy. Our paths will now part, after more than 5.000 miles side by side? Brave Cvetan, ready to dodge the icebergs.

Post by zezo | 2014-02-19 | 17:36:13

It was not very good idea after all. Bailing out.

Post by Gwellan | 2014-02-19 | 20:35:14

So the theory is that the speed is reduced by 50% in the periphery and 70% in the middle ?

Post by zezo | 2014-02-19 | 20:37:26

Yes. I watched few boats today. 50% boat speed in the first 5 miles or so and then 30%.

Post by sudoeste | 2014-02-20 | 01:24:40

Maybe the limits of the icebergs you imported from the game are the ones with the 70% penalty. If you compare the limits of the icebergs in the actual game with the ones you have on zezo, you realise the icebergs in the game are bigger. For instance, zezo is recomending a route north of the iceberg zone we're aproaching, and this route should keep the boats pointing east, between 52�53'S and 52� 54'S when in fact, if you check the map in the game, the iceberg zone goes all the way to 52� 51'S. Could it be that the difference is the 50% penalty area?

Post by zezo | 2014-02-20 | 01:31:28

That's right, see the original post. The router is more about long-term strategy. In short quarters you should always check the official interface. My chart lacks some features like small islands and such.