When covering my boat for the winter, I like to use heavy gray-green poly tarps, as they are inexpensive and last several years if they are protected against chafe and are properly secured. I’ve learned that just tying down the cover won’t keep it from catching wind, so I also fill jugs with water and tie them to the edges of the cover. That way when a gust lifts the cover, the weight of the jugs immediately pulls it back into place.
There is just one problem with this setup: the weight of the jugs tends to tear out the tarp grommets over the course of the winter. I tried putting in stronger grommets, but they didn’t last much longer than the originals. Plastic tarp clips don’t work very well either. Not only are they hard to install on the heavier tarps I prefer, but the plastic fractures during the winter.
The ultimate solution was to get some old tennis balls, which I rolled into the edge of the cover and tied in place as shown in the photograph. The balls spread the loads created by the harsh winter wind without ripping the tarp and do no harm to the gelcoat on my topsides. A similar arrangement should also work well if you want to use a poly tarp as a low-budget awning when out cruising.
Photo by Bill Bleyer