Squalls / calms are (currently) only applied in Xtreme mode.   They are in addition to the continual shifts and gusts that give momentary variation in the wind.  (For brevity I'll just use "storms" but Zephi serves up both!).

 

Heres how it works.  Every 90 - 120 minutes Zephi detemines the storm 'scenario'.   That scenario then stays fixed, until it expires and a new scenario is calculated.

 

The scenario is defined by 5 paramters:

- storm start time

- phase-in (and out) period

- durattion

- force

- scenario expiry time

 

For example:

at 09:17 Zephi might set the following scenario

- start time  09:33

- phase-in   10 minutes

- duration   45 minutes

- force  150%

- expiry 11:04

 

So, from 09:17 to 09:33 you get the 'base' Xtreme wind.   WInd speed starts picking up at 9:33, over the next 10 minutes, building to 150% of the base speed.   Wind will staty at that level for 25 minutes (till 10:08), then die back over the next 10 minutes to the 'base level', and remain there till 11:04.   At 11:04 a new scenario is determined (*)

 

So if you cast off after 10:18 you will only get normal (Xtreme) wind.   If you cas off at say 9:45 youll be bang i the middle of the storm.  Etc.   The key point is the times are not relative to when you cast off but to the scenario 'window'.

 

A 'calm' is simply when the force is < 100%.

 

When you board or cast off with Xtreme wind, you will get a weather forecast.  It will give an indication of whats to come - timing and severity.   However just like in RL, forecasts are often inaccurate and incomplete.

 

Possible / probable future enhancement ... a shift in the wind direction as well.

 

Note for WWC experts ... this is different from the built in WWC race resume in that the change is not a one time event but builds up (and down) gradually.   The phase-in time varies between 2 (think line squall) and 40 minutes.

 

Note also - this is NOT meant to be any sort of realistic model of RL weather.   In particular the time frames are adjusted to SL time horizons and 'scale'.   The idea is to give a 'storm effect' (or calm) in a simple way in the SL envirnment.  Also be aware that not all boats handle very string winds in the same fashion.  (We do have on our list making Zephi wind somewhat 'boat aware' but are still thinking through how to do that).

 

(*)  NB: The new scenario is not 'pushed' to boats but only affects boat casting off after its set.   This is under consideration ... my current approach is mainly based on - people rarely sailing for more than 2 hours at a time (single 'cruise'), and not adding extra code that would be very rarely used.