Zezo forum: Cap constant, ou angle au vent ? Constant heading, or wind angle?

Cap constant, ou angle au vent ? Constant heading, or wind angle?

Post by misterdjul | 2020-12-06 | 17:36:14

Bonjour zezo,
peut-�tre une question idiote.
Quand je suis les recommandations du routeur, il peut y avoir plus d'1h avant un changement de cap.
Dois-je verrouiller l'angle au vent ?

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Hello zezo,
maybe a silly question.
When I follow the router's recommendations, it may take more than 1 hour to change course.
Should I lock the wind angle?

17 Comments

Post by Ricard34 | 2020-12-06 | 17:52:15

Oui / Yes ;)

Post by zezo | 2020-12-06 | 18:20:26

Check the red, green and blue projected lines. If the green one matches the track then lock the angle.

Post by Gabriel | 2020-12-06 | 23:04:21

When we put the mouse over a black point, it displays a window with a direction and a TWA. Which one should we follow until the next point ? How does Zezo calculate it ? With a locked wind angle or a locked direction ?

Currently my next 5 points (including the one on my current location) comming are saying TWA = 145 but if I try to pu the green line on theses points, it matches with a TWA = 149� ... where does this difference come from ?

Post by fab | 2020-12-07 | 19:14:14

Hi Cvetan,

A great feature for Zezo router would be :

Restart a projected track ( HDG, TWA )starting From a selected point in the computed track.

possible ?

Post by jokap | 2020-12-13 | 03:04:31

Wouldn't it be the easiest solution to just highlight or print in bold whether to use TWA or HDG in the little window appearing when hovering the mouse right over the respective waypoint in the router?
Thank you, Cvetan, for the great work!

Post by zezo | 2020-12-13 | 10:57:09

The router does not really know. It just wants to travel the most distance in given time, that's it.

Post by jokap | 2020-12-13 | 16:27:31

Oh, okay--that was not clear to me. However, I can see how users struggle to be able to tell whether to use constant HDG or TWA when the navigational points are really close together as in that case the different projected trajectories differ so little that visually it is hard to tell which one to follow...
Anyway, Zezo, thanks again for your great project! It is the one thing that makes playing in the virtual regatta a bit more manageable--considering all those bugs the professional team of VR just seem to not be able to get rid of :D

Post by Retsam | 2020-12-13 | 08:23:22

Sorry @jokeap: would you mind to use your mind, please? Think about designing a robot playing in your place. One of the specs will be just what you said.

Have fun!

Post by jokap | 2020-12-13 | 16:20:41

Wow, Retsam -- great advice! Why do you use zezo anyway, instead of using your mind?! There really is no need to become insulting...

Post by zezo | 2020-12-13 | 16:23:26

Yes, we are trying to keep friendly community here and rude comments are not welcome.

Post by jokap | 2020-12-13 | 16:30:44

So true, Zezo!
Which is why I would like to apologize to Retsam for the payback--I am sorry.
Again, Zezo, keep up the great work--and hopefully you won't have to do too much kindergardening--including me^^

Post by zezo | 2020-12-13 | 16:31:45

@jokap use the projected track tool as much as possible.

There is also another extension that shows overview of the data as a table:

https://chrome.google.com/webstore/detail/route-zezoorg/hfmdbddgjlicmflejkkoafbkdgnfggbg

That said, the router does not always get the optimum TWA right, so check the polars, and sometimes there is more than one way to achieve the same result.

Post by jokap | 2020-12-13 | 17:00:53

Thank you, Zezo, for putting up with noobs like me! :D

Post by zezo | 2020-12-13 | 17:14:06

It's part of the job description. A router is a router, but there is more to it. The main tool is not the track, btw. It's the isochrones. The blue lines that show all possible positions at any given time. You have to learn to read them like the height lines on a topo map.

Post by jokap | 2020-12-13 | 23:12:32

I see--so the route being displayed is a mere hint or rough indication for the optimal route? And the potential lines/isochrones together with the projected trajectories are the real tool for finding the best solution?

Speaking of the isochrones: Do I get it right--an isochrone is the envelope to the set of time-scaled polar charts to a respective set of discretely spaced points on the respective previous isochrone?

Post by zezo | 2020-12-14 | 09:30:29

The router is strategic tool. Main purpose is to tell you where to sail to get a good wind in a week - that's the part that's hard for humans.

It could also do game-specific short-term optimization, but that would require different logic and could lead to the fleet spreading less, so I'm leaving it as exercise for the reader ;-)

Also, never forget that the forecast changes every 6 hours, so the most carefully planned track may become a fiction in that time. Here some real-world sailing rules of thumb come into play.

The isochrones - yes. They are sets of polars for the corresponding wind speeds and directions. In a constant wind field the isochrones would look exactly like the polars, only with straight lines between the upwind and downwind VMG angles because the router will tack/gybe and not sail blindly into the wind.