Zezo forum:

Post by BooBill | 2020-07-10 | 00:39:38

I've gotten burned by this many times and just fell for it again, so I have to ask why?

I had a bearing of 120 set for the Arctique. When I last checked after the weather update the router was indicating to hold that TWA till after the next weather update. However, I got timed out of VR over dinner and when I logged back in the new route that was autogenerated had me sailing 110TWA. I've noticed this before. Sometimes the route is a completely different strategy. Usually, I wait till the next 10 minute update to run the route with fresh coordinates before making any course changes, just to be sure. However, this time I reacted and made the course change because it appeared that a lot of other boats had headed up a bit. After incurring a sail change I check the rest of the pack. Shit, only that one boat I had looked at before making the move had actually headed up, everyone else was still at 120TWA. When I ran the route at the next update from the server, sure enough back to 120, exactly what I saw before dinner.

So, has anyone else noticed this? When a route is autogenerated upon login, does it take your start position from your actual position at that moment, from the last server update, or is VR feeding the router BS?

8 Comments

Post by Hardtack | 2020-07-10 | 12:40:08

As to your second question, the VR server sends a status message when you log in to race, containing the boat position and other data. VR Dashboard calls the router with this position. Looking at the race log, it seems to be more recent than the latest 5min update.

Btw, I'm fairly sure a few weeks ago, the server just repeated the latest 5min update. And about a year ago, it sent fresh updates like it does now.

Post by BooBill | 2020-07-10 | 17:54:20

So, basically, don't trust it and wait till the next update to make any course changes. Also, do not swirl the compass to bring up debug mode when you have program points set.

I've learned a lot from you today Hardtack. Thanks.

Post by MidnightFoiler | 2020-07-11 | 03:37:35

How about we change the dashboard to give zezo the last position closest to a 10 min boundary? Or add wheels to the race log column so you can do so manually?

Post by BooBill | 2020-07-11 | 09:51:44

I would prefer to have it be your live position if that's possible and we knew for sure that's what we were getting from VR. That way exiting and re-entering a race would give you a live update in between server runs.

Post by MidnightFoiler | 2020-07-11 | 10:05:43

That is what it does now BooBill. You don't always get an update from the server by re-entering ... seems to me to need to be 2 mins or more later than the last server update.

What that means though is if you re-enter at 10:08 you will get a zezo route from 11:00 but using your 11:08 position as the start point.

Post by Hardtack | 2020-07-11 | 13:57:10

@MidnightFoiler this is my observation too. But you probably want a routing immediately when you log in. On the first login all we have is a position that may be 2-3min old. If you want to align the start time with zezo just call the router again on the next 10min boundary.

That's what I do, but it feels a bit superstitiuos. Such small differences shouldn't really affect the routing. On the other hand I think that the 10min interval sometimes misses the optimal tacking point and the router tries to approximate by pointing lower than optimal VMG or it oscillates between two similar routes.

Post by BooBill | 2020-07-11 | 14:57:34

It's my observation that sometimes it makes a very significant difference. Light winds, slow boat, steady wind, no biggie. On an Ultim moving fast in shifting winds, it can be huge. I've lost count of the times that I've sat down to the computer later than I wanted to, logged in, panicked and reacted. Re-running the route on the next 10 minute update finds that I was on the correct trajectory and now I've just done 2 unnecessary sail changes.

I make it a point of only really trusting routings run with my finger over the button waiting for the 10 minute update. However, it's hard not to react to what you first see if you've come home late from something.

Post by MidnightFoiler | 2020-07-12 | 12:15:36

Yes Hardtack, that is what I do too. I also sometimes try the 5 min routing heading into a tack or gybe to see if it thinks I should go 10 mins earlier which probably means a tack 5 mins earlier is ideal.

Interesting what you say about the VMG. I recently saw an assymetry of TWA before/after the tack in the low wind transition in Arctique and did the 5 minute route and it was symmetric at optimal VMG.