I have a 14' aluminum boat and put a carpeted deck on it. My problem is the boat stays at my dock no cover so it's exposed to the elements. The problem is I store my tackle in there and am tired of opening the hatch to find water in it. The lid is just a board cut to size that rests on a lip so it's flush with the deck. I've bought flambeau zerust waterproof boxes but am still worried that my lures will rust. Any suggestions how to keep water out or minimize it?

Sorry, but you are not going to keep water out of your setup. I would cover the boat.

Ziploc makes some waterproof storage boxes called Weathershield that have gaskets around the lid seal. They may have something in a size that will fit a few 3700 boxes and still fit under your deck.