I am with Tate on this! I'm switching to using "BEHR PREMIUMĀ®
Transparent Weatherproofing All-In-One Wood Finish" on our Douglas fir bowsprit, and that'll be the only thing top-side that has a coating. I tested the stuff on a cedar planter box that I built for our balcony at home, it has been sitting directly in the Florida sun for a year and a half with two coats on it, only on the faces as well, and the coating has held up very well. I'm sure that the bowsprit, encapsulated in the stuff, will be fine, and it is extremely easy to reapply. Water-based, so easy thinning and cleanup, and all you have to do is scuff the surface with a green 3M pad before reapplying. It's about $12 for a quart.
As someone else pointed out a while back, these big companies that market to homeowners have a lot more money to throw into figuring out good formulas, and as far as I can tell this product is about as good as you could ask for in terms of protection and ease of application, and it looks quite good.
-Aaron