Having the same problem although it has been pretty windy yesterday and today. This is my first closing too. I haven't winched down the cover yet. I have bleach bottles with bungey cords holding it down for now along with some cover clips. I think I need some adjustement with mine. I noticed the the cover isn't sitting on the water which I think is why it's flapping around a lot. I'm going to be adjusting it some more after work. My cover clips keep falling off too which is annoying!