@aztabona I tried this trip planning between Lefkada and SE of Sicily. When the speed is turn off, there is some thunderstorm on the route, which disappears when the speed is turn on. Without speed it is the weather on the route at your start time. Then when you are sailing at your speed the boat does not encounter the same weather as it was at start time along the route. By the way why do set your speed in m/s when kt are available (click on the speed units)