Carolena
Guru
Excellent article on marine sealants that includes a discussion regarding the use of Butyl Rubber sealant, something that has been discussed here in the past. Full disclosure, I've had great success with butyl for deck fittings and have found the best butyl to come from the source mentioned in the article (tried other sources, like big box stores and RV suppliers, and the article is right - not all butyl is created equal).
How To Pick The Right Sealant - BoatUS Magazine
How To Pick The Right Sealant - BoatUS Magazine