In my opinion, the use of either a hair dryer or heat gun is the fastest and cleanest method to use, when trying to remove vinyl decals or stripes. Usually, you can remove the decal in one piece, once you get an edge started. You might want to use a plastic scraper or putty knife, so that you don't scratch the gel coat.
Some people rave about the use of a stripe removal tool made by 3M. You can buy them in an autobody or paint supply store. I didn't see them in the Boat Fix catalog. Basically, it's a rubber wheel that you use in a drill. My experience with this product it that it's a PIA to use and very messy.
Bob