From boating magazine...
Polysulfide
BoatLife's Life-Calk is the sole polysulfide on the market. Its flexibility, resistance to chemicals, gas and diesel, plus sunlight stability make polysulfide a good choice for bedding fuel fills and teak decks.
Silicone and Blends
Silicone is primarily a sealant — a flexible, sunlight-resistant gasket, not a glue. For waterproofing hardware that you know must come apart again someday, like navigation light fixtures, marine silicone products from 3M, Star brite, West Marine and BoatLife are hard to beat. BoatLife's Life Seal is a blend of silicone for UV resistance and polyurethane for better adhesion. The 3M 3000UV is an SMP formulated for less adhesion, specifically for sealing.
