Sealant Shorthand

By Don Casey

Revised by BoatUS editors in April 2012

What type sealant to use can be confusing. Here is the code:

  • Use silicone to electrically insulate dissimilar metals and to bed plastic.
  • Use polyurethane only to join components that will NEVER need to be disassembled.
  • Use polysulfide for everything else.

There are exceptions, but following these three rules will avoid most wrong-choice problems.

Don Casey has been one of the most consulted experts on boat care and upgrades for 30 years, and a panelist on our "Ask The Experts" website for a decade. He and his wife cruise aboard their 30-footer part of the year in the eastern Caribbean. His books include Don Casey’s Complete Illustrated Sailboat Maintenance Manual, and the recently updated This Old Boat, the bible for do-it-yourself boaters.

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