Southmark, You're right! My math was OK, but my science was bad. Nevertheless, there ought to be plenty of light to make shadows in the deep, dark woods. The old custom among the 'Gullahs' and 'Geechees' in the low-country of SC was to paint their door and window frames blue to keep the 'haints' away. As far as I know, it worked pretty well for the most part, so, I'm gonna use an Amsteel Blue ridge line on my tarp, just for safety's sake.