For the last several years I’ve been using
Griot’s 3-in-1 Ceramic Wax spray above the rub rail on our Cobalt, and on our cars. (I leave the hull to the marina since we’re in a slip throughout the season). I apply it twice per year, first thing in spring and again in the late fall, and it holds up quite well, leaving a good shine and very good water repellency/beading properties. Very easy to apply, just spray on and wipe right off, no drying time needed.
Like Woody notes, a well prepped clean surface gives best results. Wash with a high ph detergent or use a surface prep cleaner to remove any old wax or sealant before applying the ceramic wax product. Griot’s also sells a detailer spray (Ceramic Speed Shine) for keeping everything nice and shiny.
Of course it’s not as durable or equivalent to a full blown ceramic treatment.