
Post by
zezo | 2018-01-01 | 18:00:48
Most of the time there are many different possible routes with very close outcome, so every 10 minutes the router may pick slightly different version.
Sometimes it can be relatively big change - there are spots in come polars where 15 or 20 degree TWA difference gives very close result.
Then the boat does not move exactly as predicted because of the small differences in wind speeds and interpolation details so you start from slightly different conditions. The game also does not execute your commands exactly - it introduces +/- half degree difference in both TWA and heading commands.
And then the routing step changes over time. Smaller step is more accurate, so the forecast 12 hours in front of you may still be the same, but the traveled distance with 20 minute vs 10 or 30 minute steps will be different if there is temporal or spatial wind gradient and so on.