Dicor or Eternabond Tape -Which is Better

Bob B wrote:
Has anyone tried the 3M 4200 or 5200 marine sealants?

I will only use 3M polyurethanes on the roof. I prefer 3M 4000 UV which yellows less in the sun. The extra strength of 5200 is usually unnecessary (though I did use it for the solar panel mounts, there being no other fasteners).

However you will not get good results by dribbling it on the outside of a joint, as Dicor is intended (apparently) to be used. Pull off the vent or cover, clean it up, and reseal it properly with polyurethane if you are going to do it. I posted some pictures awhile back you would find with a search. However some seams, like the one in the OP, would be very difficult to open and reseal properly, so you are left with the band aid approaches. Also rubber roof materials may not be compatible with polyurethanes, I have no experience with them.

Regarding longevity, the standard strategy in the RV business is to fix the leaks in the roof (again) every year. This would never be done on a yacht. On my last Bigfoot camper, shortly after my new purchase in 1998 I scraped the mess of Dicor and silicone from the roof and resealed all the vents properly. I sold it last year with no leaks and no roof maintenance, the new owner has not touched it either, 16 years now leak and maintenance free. I am a believer in the old saying, "If you can't find the time to do it right, how are you going to find the time to do it again?"