I just repaid the deck seams one IDUNA's companionway hatch. We use 3M's fine line tape as a bond breaker. It is made in various widths from 1/8" and wider. The 1/8" works fine. To removed the seams, we used the Fein Multimaster tool with seam removal attachment - highly recommended. Once the caulking was removed, I used 80 grit sandpaper wrapped around a tongue depressor to sand the seams.
We did this job in 2003 but after 4 years the Boatlife Type P polysulfide caulking failed - see photos. The caulking cracked, shrank, became sticky and soft. This only happened on section exposed to sunlight. The section under the seahood appeared sound. The seahood was also caulked at the same time as the hatch. This still looks new. BoatLife has been less than sterling about this problem. My understanding is Detco two-part polysulfide is a better product than Boatlife's.
Detco is available on the West Coast but not the East Coast, hence I used BoatLife's Type P again.
Edited 1 times. Last edit at 09/23/09 05:09PM by IDUNA.