It is an “old school” joint on a thoroughly modern boat.  The deck on a Melges M20 meets the hull like the lid of a shoebox.  A string of screws or bolts hold the two parts together, with a rubrail on the outside, and in some cases,  a strip of wood on the inside.

Flexing parts and old age will over time cause the sealant between these parts to crack and leak.   Heel the boat properly and the pressure will gush water into the cockpit, like an artesian well.  Worse, in a capsize, the hull will fill quickly and submerge.  The fix is straightforward:

• remove screws,
• wedge the hull apart from the rub rail,
• clean out the old sealant,
• squirt new stuff in between the rub rail and deck
• bolt it down again.

But there are some nuances.  Follow the fearless Tripp below as he works on the starboard gunwale of the 1977 M20 known as “Avocado.”