Notice:
The advice given on this site is based upon individual or quoted experience, yours may differ.
The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.
Used blue poly-tarp for four winters now with bungee-cords and one half inch rope wrapped around top of tarp and boat to keep it from tearing in the wind. No UV damage here.
As long as you can keep an eye on it you should be OK. The biggest concern I've had is excessive wear at points of contact with hard points. The most frequent place is the part that crosses the back end of the boom. As Bear noted, creative lashing (and some cushioning) will help with that.
One caution: keep an eye on the winch covers. Mine got a bit beat up when the wind moved the tarp. but nothing critical.
If the tarp is to be draped over the boom and you leave the sail/sail cover on, make sure the tarp is secure and cannot move. One winter I had a tarp over the boom (secured at the sides by bungees), and by spring my sail cover had a dozen pin holes where the tarp had worn through during the winter winds.
Notice: The advice given on this site is based upon individual or quoted experience, yours may differ. The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.