Bought 4 20ft and about 10ft to place on our breakwater which is a flat concrete (sealed concrete) surface. Dressed up, got up the next morning and rolled back into the yard two o'clock! Light 10 mph breeze, no storms, strong winds and waves as the lake was calm. Dried them out, stacked them as recommended by the company representative, left the cottage, returned about 10 days later and they lay scattered like dominoes on the grass in the yard, rolling down the flat top of the breakwater, what…