It is my humble opinion that all finishes, if submerged in water long enough, will fail. If high durability is your priority, a two part, slow setting epoxy is the answer. There is really no laquer (like DN's), urethane or waterborne clear that can compete with its durability. The waterborne that we use claims that it is as durable as a two part epoxy, but I don't believe it. It works well for us becuase we only make topwaters, and we like to dip the final coat. By its nature, epoxy bonds to form a new crosslinked polymer that cannot be chemically broken. Laquers and urethanes just have a solvent that evaporates, and what remains is your finish, so they can be 'uncured' with a stong solvent or even water that has a high alkalinity.
John
Aiden James Lures
http://AJLures.com