Well after all that wind at least I now know how strong my boat cover is - 68 mph strong
At one point last night we did wonder if we should remove it incase it got ripped off - but then I figured we were past the point of no return. If we had have started to remove it we would have been blown away ourselves. So we left it and every hour or so looked out the window anxiously.
All fine now. But I think next time I may take it off just to avoid a whole evening of wondering.