This app converts apparent wind to true wind or ground wind, depending on the inputs for vessel speed and heading. This is a computation needed daily by sailing vessels underway and by ships reporting weather to national agencies. Use SOG and COG from the GPS for speed and heading to get the "true wind" used in official forecasts (sometimes called "ground wind") or use true heading derived from compass heading and knotmeter speed to get the" true wind" used on sailboat’s polar diagrams (sometimes called "water wind). Likewise this app does the reverse computation, true wind to apparent wind, so a mariner can forecast expected apparent wind based on a forecasted true wind change and known true wind boat speeds from a polar diagram. This allows mariners to plan for the sails needed and the courses available to them when the new wind appears. The app is designed with a simple, clean interface for efficient use.