I had a rigging tube installed that runs from my bilge area (below the cooler cutout) to my coffin box on an Ankona Shadowcast so I can run power and ducer cables to a GPS/FF on my grab bar. Once I run the wires I would like to water tight that tube in with a cover I can remove without tearing up the deck surface whenever I need to re-run more wires. I am thinking of using a piece of starboard or similar flat cover and some type of caulk-like adhesive as shown in the picture below. What would be the best combination of material and adhesive such that it would be water tight and yet removable (~every 3-5 years)? Or if you have any other ideas on the best way to prevent water from getting in the tube please let me know. Its got to be relatively flat because a cooler will be sitting above this hole, so a riser of some sort probably wouldnt work. Thanks for any and all ideas.