The Distance & Planning (D&P) tool is great. I recently used it to plan the best day and departure time for crossing the Gulf of Mexico from Panama City to Tarpon Springs Florida in a sailboat. This passage cut across what is called "The Big Bend" around the Florida pan handle and the main part of the peninsula with few suitable ports in between. This is a 210 nautical mile (nmi) trip which at 7.5 knots (kts) takes about 29 hours, most of the time out of sight of land, cell phone coverage, and even VHF radio coverage. Because there are no real good ports to put into along the way if the weather turns bad, having a good forecast along the route is important. The first improvement that could be made, is to support waypoints imported from GPX files. Currently the path (course) is imported, but not the waypoints. I got around this problem by plotting my course with a zigzag pattern with legs a little longer than 15 nmi which corresponds to 2 hour legs at 7.5 kts, export the file from my navigation program in GPX format, then import into Windy, and use the D&P tool to plot a straight course with points that correspond to the zigzags. Then I picked a start time and date, looked at the forecast at point 1 for cloud cover, temperature, wind direction and strength and wave height and direction, then advanced the time by 2 hours and looked at the forecast at point 2. I repeated this process for each of the times/points along the route, then did this whole procedure for different start dates and times. I found the best day and time to make the passage with this process. During the passage, I made weather observations at each 2 hour interval, and the weather, wind and wave forecasts were very close, and the passage was comfortable.
One other improvement would be to automate this process. If the user could lay out a route with the D&P tool, set a speed, then enter a start date and time and have Windy display the forecast at each point along the route at its appropriate time, that would save a lot of manipulating the forecast tool time scale.
Thanks for a very useful tool.