The SailTimer app is free. You can import the excellent Navionics charts with in-app purchase. Display your optimal route through multiple waypoints.

Compare 3 different types of marine weather animations: AI forecasts (European model), crowdsourced wind maps and NOAA GRIB (US model) and Weathernews Inc. (WNI) weather for ships (Japanese model). When they are all consistent, you know your routing is based on accurate information. Each has a low-cost in-app subscription and 7-day free trial.