I''d recommend shrink wrap if you store your boat in a windy location. My 34'' sloop is stored on Lake Champlain and it''s common for the tarps to tear during winter. Even when they don''t tear the make a mess of your boat as they break down and wear. I tested shrink wrap last year for $10/ft. I liked the cover but hated throwing that much money away each year.
I purchased my own shrink wrap gun after finding out that the wholesale price of 20''x90'' shrink wrap is about $80 (so the cost of materials is about $50/year). Friends could easily share the cost of the heat gun and pay for itself the first year.
Be sure to ventilate and don''t wrap a painted hull