Zezo forum: clarification - Ice exclusion zone for dummies

clarification - Ice exclusion zone for dummies

Post by freudenoli | 2020-11-15 | 21:37:10

my apologies if I test the patience of smarter people...I did read the posts about ice exclusion zones and how to navigate along them...but I am still not sure I understood correctly...so could please somebody confirm:

- is it safe to sail the boat on a compass course parallel to the exclusion zone over a longer distance without danger to cross it?

- is it safe to program two waypoints parallel to the exclusion zone over a longer distance without danger to cross it?

- if you set a timer programmation approaching the exclusion zone very closely, is there a danger that the boat overshoots the programmation and gets you into the exclusion zone?

many thanks for your answers and patience!

17 Comments

Post by Jeanbern19 | 2020-11-15 | 21:39:10

Hello ,
yes there is an obvious risk

Post by zezo | 2020-11-15 | 21:47:24

1) Probably yes.

2) Probably no.

3) Probably yes.

To elaborate a bit:

1) It should be safe, but the compass course you set is not exact. Game shows it rounded, but in reality it's +/- 0.5 degree

2) Ice limit is _probably_ defined as loxodrome. Waypoints are sailed on orthodrome. The two lines will cross sooner or later, especially on that latitude.

3) There is always danger with the programmer. Like not executing at all, or using the wrong forecast, resulting in wrong distance

At some point this game becomes quite tiring. It takes a lot of effort to be at the top. Alarm clock at odd times to pick the best moment for a tack, waking up every morning at 5AM to check the new GRIB, etc.

Post by freudenoli | 2020-11-15 | 22:44:46

thank you zezo!
is it possible to say what should be a safe max distance two waypoints can be set apart without loxodrome/orthodrome crossing at lets say 45 south? 10nm apart...50...100?

Post by zezo | 2020-11-15 | 23:00:14

That is related to how close they are to the line. If you place them exactly on the limit than you'll cross it, no matter how close the waypoints are.

The crossing will be visible in the dashboard map and in the game itself. but we can't be sure of the exact implementation, so that may not be useful.

Post by PML | 2020-11-16 | 08:30:13

A question for Hardtack: would it be possible to display on the Dashboard map the future boat route (at least for boats sailing at constant heading) - same as when using waypoints ?. It could be useful when it comes to navigate as close as possible to the ice exclusion zone...

Post by Hardtack | 2020-11-16 | 09:19:57

It can't - computing the future boat path requires wind information, but the Dashboard doesn't have it.

Don't forget the game still has a UI :-)
If you can't actually use it to navigate your boat, I think it would be justified to turn to the game providers asking for improvements.

Post by PML | 2020-11-16 | 10:16:05

Thanks for the swift response. Understood. What about a rhumb line in front of the boats sailing at constant heading (to see if their future path are set to intersect the ice limit line) ?

Post by zezo | 2020-11-16 | 10:22:47

A dimensionless course projection could work - graduated in distance, not time. But that would re-implement existing game functionality.

Post by PML | 2020-11-16 | 16:14:20

Yes, but with more accuracy (for some reasons, I do not trust what the client displays).

Post by rids | 2020-11-16 | 13:43:12

The edge of the IEZ looks like a pedestrian crossing when zoomed in. is the speed penalty already effective if you cross the lighter areas , or is it just a warning signal ?

Post by YourMomSA | 2020-11-16 | 14:19:30

I've been wondering the same. If no one knows yet, then whoever gets there first will find out. :-)

Post by rids | 2020-11-16 | 19:20:42

Quote from the VR help page :
https://virtualregatta.zendesk.com/hc/en-us/articles/115001442713-What-are-ice-zones-

This limitation is added in order to get as close as possible to the real race course. As is already the case for all races, the white line on the map shows you the route to follow.

A boat crossing this line or sailing on the wrong side of the line has its speed greatly reduced.
It is therefore important to keep clear of this boundary by navigating on the side indicated by the white line, without sticking to it.

The dotted area shows the danger zone to avoid when navigating.

In fact, when sailing in the far south, your trajectory between two points may not be strictly straight and you could cross the line without noticing it.

Caution: this line may vary and be placed at a different latitude during the actual race.

Post by BooBill | 2020-11-16 | 19:38:24

So, since they explicitly state the line can change during the course of the race, and they will follow the real race, that means it will be made without regard to virtual boats who might be within track limits currently, but caught outside by the change.

Any guesses what happens then?

Post by zezo | 2020-11-16 | 19:55:26

That should not happen unless the virtual boats are days ahead of the real fleet. Real world sailing instructions can't be changed on a whim, there should be some advance notice, and there will always be a real boat close to the current limit.

Ooops. I just read what I wrote and realized that we won't get the advance notice. Someone should be checking the VG site daily for amendments.

Post by YourMomSA | 2020-11-16 | 21:07:26

It seems likely the leader of the real race will be well ahead of the leader of the virtual race. Once the other top foilers hit ideal foiling conditions, several of them will be ahead of our fleet and won't come back unless they break down.

So I guess the main question is whether or not the real life race can change the lice limits behind the real life leader. Ordinarily, I'd say absolutely not. You can't change a race course behind the leader, in general. But... given that the ice limit is a safety concern, perhaps I'm wrong about that.

If they won't change it behind the real leader, then we probably don't need to worry about it suddenly shifting over a virtual boat's current position. However, it'll still be important to adjust the router's data whenever the limit changes. The current projected downwind lane Eastbound is pretty narrow.

Post by nrten | 2020-11-19 | 07:04:47

I watched a vendee globe update yesterday. They were explaining, that the race committee will have to set the ice exclusion zone right before the leader reaches it and not change it any more, as otherwise the rules would be different for different sailors. Which would make sense, right?