Leaving your spin outside in your snuffer would decrease the life alot more than 10-20%! Especially in Florida.
Why do you say that?
the guys i sail with have had the same spin in their snuffer for years... with 100's of uses.
One guy even told me last week he has never even rigged his spin. he never took it off the boat since he bought it.
Mine is about 6 month old with over 70 uses (est). I have had some small holes where the retrieval line has burned through the cloth... but not bad.
