Hopefully nothing...
Knowing that epoxy is generally regarded as the best and longest-lasting sealer, I personally still opted to run a high-quality deck sealer from Behr with a 5-year deck rating and 15-year fence rating. I guess I’ll let you know in 5+ years if it’s worth it...! My reasoning:
1. Convenience and cost
2. It will be coated thoroughly, with extra care to seal areas of exposed lamination like edges.
3. My boat will not be used much (~6 times per year max, realistically) and won’t be stored outside in the sun. I’m guessing I could get 10-15 years out of it.
4. All wood will be carpeted. The coating will also likely long outlive my carpet, so if I recarpet I can easily add a coat or two of sealer.
5. I don’t need the sealer to last my lifetime. Worst case scenario...I’m forced to work on my boat in 10-15 years, and my son will be old enough to help, so that sounds like a fun project to do together!
If my boat was going to see more use and/or harsher storage conditions, I probably would have opted for a sealer with more durability and longevity.