through hull sealant mysteries

I removed a through hull yesterday. Bronze 1" (too small!) cockpit drain. This was an original equipment through hull, factory installed about 43 years ago. The through hull sealant was still functioning well. It was soft, had amazing elongation capability, and was black. I surmise the sealant is butyl rubber similar to that which is used in bedding auto windshields today. With the sealant functioning so well for so long, why do we not hear about it being recommended and highly touted today for use as a marine sealant? Why do we only hear about expensive, high tech, problematic "stuff" such as 5200? (and yes, I know 5200 is not a sealant, it is an adhesive.) Why can't butyl sealant or tape be recommended for doing jobs like sealing through hulls above and below the water line? Reggie

Reggie, let me guess. Now, in addition to everything else that has been going on, your hands, shirt, pants seat, and boat cushions are coated with a black goo. I love the way that one drop of caulk can somehow expand to cover the whole county. No idea on the caulk, but your guess sounds about right. Could also be something like LifeSeal adhesive/caulk in black. Best of Luck Charlie From: Ca… [at] yahoogroups.com [mailto:Ca… [at] yahoogroups.com] On Behalf Of r good Sent: Saturday, April 21, 2012 9:11 AM To: ca… [at] yahoogroups.com Subject: [Cal_Boats] through hull sealant mysteries I removed a through hull yesterday. Bronze 1" (too small!) cockpit drain. This was an original equipment through hull, factory installed about 43 years ago. The through hull sealant was still functioning well. It was soft, had amazing elongation capability, and was black. I surmise the sealant is butyl rubber similar to that which is used in bedding auto windshields today. With the sealant functioning so well for so long, why do we not hear about it being recommended and highly touted today for use as a marine sealant? Why do we only hear about expensive, high tech, problematic "stuff" such as 5200? (and yes, I know 5200 is not a sealant, it is an adhesive.) Why can't butyl sealant or tape be recommended for doing jobs like sealing through hulls above and below the water line? Reggie