Zezo forum:

Post by 3dayslate | 2015-01-21 | 16:01:17

Several times I have noticed zezo giving 'variable' results on when to tack.

Example 1. Right now it says I should tack in 5 hours, but ten minutes ago it said I should tack in 1 hour and in ten minutes time it will likely tell me to tack in 5 hours again

Example 2. Zezo tell me I should tack in 30 minutes hours but when I get to the 30 minute point, zezo often will tell me to wait for another 10 minutes. And then another 10 and so on.

Example 3. Zezo tell me to tack and I tack and then after 10 minutes it tells me to tack back.

I am not criticizing because it is a great tool. I would just like to understand the tool better:-)

7 Comments

Post by zezo | 2015-01-21 | 18:39:42

Assuming there is no weather data between the updates (which is a separate case) the reason for this is that most of the time there is more than one track that would result in the same position. The router does not keep state and selects one of them at random with each new calculation.

The routing "step" also varies with the time. First 6 hours are run with 10-minute step, then 20-minute step up to 24 hours and so on, and this will change the calculations slightly as your boat moves.

Post by 3dayslate | 2015-01-21 | 19:03:26

Hi, thanks - that answer is actually quite reassuring!

Post by Sir_Petrus | 2015-01-22 | 00:39:24

Zezo is keeping postponing my time to turn north. Since I am very Fidel to who helps me (and zezo helps me a lot) I will turn when it tells me to to turn or,big bird turns or, my bottle of whiskey turns dead.
Life is hard and then you die. So lets have some fun.

Post by zezo | 2015-01-23 | 01:13:13

It was the same here "tack in 1 hour" for 6 hours or so. It probably did not really matter with the current forecast, so the exact moment was a matter of preference - stay closer to the straight line or risk with some leverage.

Post by RickW | 2015-01-23 | 03:51:15

Petrus, you are the man. Hilarious. How can I not support him.

I arise in the US Pacific time (0300) for a course tack and it is delayed 20 minutes. I wait to find it is delayed another 30 minutes. And, so the drill goes. Yes, I understand the bottle.

I have the same issue with a current wind routing that is planned at the helm and each time the zoom is used it is changes. I agree it may all go to the same place, but it still confuses the mind; my mind.

Speculation: If the wind had not changed, could we freeze or select a route. Would this require massive donations? This is getting to be fun Heh, Petrus.

Post by obloviate | 2015-01-24 | 13:51:03

For those 0300 'rises' I suggest my technique; I hook myself up to an IV bag of Vodka on a stand with wheels and shuffle between the bed and the Bridge as needed for 3+ weeks!! No pain, just disappointment when we reach port!

Post by WretchedExcess | 2015-01-24 | 16:18:24

Not to go totally off topic but obloviate reminds me of Bill Murray in the movie Where The Buffalo Roam. (The story of Hunter S Thompson) By the way Thanks for this these charts. They allow me to get some sleep.