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 is one of the BoatUS Magazine's panel of experts. 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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