If you want to buy a (new) windsurf board and you are not shure what minimum board volume you can handle, you can use this app to calculate a minimum board volume required. It avoids that you buy a board with not sufficient volume to keep you floating under non-planing wind conditions. Meaning, that if the wind speed drops during your surf session and comes under a decent planing level, you might end up swimming to your home spot, as the board floatation is not enough. This app takes body weight and the weight of all gear components (like sail, mast, boom, wetsuit weight etc.) into consideration. Smartphones as well as tablets are supported devices.