A rubber O-ring on these plastic deck plates creates a watertight seal for safety. Screw-in style has a single-start, non-jamming (no cross-threading), extra-strong, self-cleaning buttress thread. Use only 100% silicone caulk. ShWt .4
The West Advisor articles have answered boaters' questions and provided solutions to boating problems for more than 20 years. West Marine has compiled one of the Web's most comprehensive collections of technical boating information articles.