One seam between the deck and the coachroof has definitely given me a headache! I repaired it twice last season, but unfortunately the caulking had once again separated from the teak. I believe that the problem with the repairs done during the sailing season is that the teak does not have enough time to get dry thoroughly. It may take at least a week or so for teak to dry thoroughly, and you are not always that lucky with the weather in Northern Europe. If the teak is not completely dry when making the repair, there is a risk that the caulking is pulled off when the teak shrinks. Furthermore, deck gets frequently washed with seawater when sailing, so it makes the repairs during the sailing journey more challenging. And you do not want to spent a week at a harbour just to get one seam fixed…
After the old caulking was removed, I injected some epoxy under the teak planks. There appeared to be a void in the corner of the coachroof and deck, and this was a place for water to collect. The void was easily detected as the spot remained wet longer than the surroundings. Thus I decided to fill this void with SP 106 epoxy. I was influenced by this sailor/blogger, who used epoxy injection on deck repairs as well. The repaired seam is now let to dry under the tarpaulin for a while, before I start cleaning the deck.
The new caulking after the masking tapes are removed. There is no need for sanding the teak.