Boat Hull Joint Repair

A rub rail at deck level is often the culprit.

The joint between your boat's hull and its deck can leak over time. If you've ruled out a crack in the fiberglass, look at the rub rail. If the leak doesn't come from the deck or the hull, it's probably from the failure of the caulking behind the rub rail on the outside of the hull, at deck level. Recaulking around the rub rail is a temporary--and visually unappealing--solution. The only permanent solution may be to remove the rub rail, then recaulk and reinstall it more securely than it was originally installed.

Things You'll Need

• Screwdriver
• 3M 5200 Marine Adhesive Sealant
• Drill
• Screws

Instructions

1. Remove the end caps from your boat's rub rail with a screwdriver. Remove the rubber pad from the boat's aluminum rub rail mount by sliding it out of the end of its aluminum mount.

2. Remove the screws that hold the rub rail mount in place. Remove the mount and set it aside.

3. Clean out the dirt and foreign material from the joint between the hull and deck with a plastic scrubbing pad. Smear sealant into the joint with your hand or a putty knife.

4. Replace the rub rail on the side of the boat. Drill additional holes in the rub rail mount, halfway between each pair of screws that hold the mount in place.

5. Insert an additional screw into the newly drilled holes to make the deck joint tight. Return the rubber pad to the rub rail and replace the end caps.

Tips & Warnings

• With older boats, the former owners likely have tried bigger screws in the joint (deforming the joint) or bigger screws in the rub rail without rebedding the rub rail in new caulking to prevent the water from gaining access.

• Use the smallest-diameter screws possible. If you remove the rub rail completely, you may use a caulking gun, but your hand or a putty knife will give better coverage.

References

• "The Fiberglass Boat Repair Manual"; Allan Vaitses; McGraw Hill Professional, 1988