Zippers or Velcro on cover
 

Cutting up newer universal boat cover to go around tower legs. Any ideas on what type of fastener works or holds better? If so, what type of zipper or velcro?
I heard the adhesive velcro gums up the sewing needle.

If you need strength go with a zipper. But, most zippers degrade in the sun. So, if you need sun protection add a velcro flap that covers the zipper.

BTW, I am looking into making my own sunbrella cover for my little fishing boat. I think I can buy a sewing machine and the material for less than it would cost me for a custom cover.