Deepen the grooves
All teak deck owners know the problem: after so many years and maybe a sanding job the deck gets thinner, causing the rubber to get loose and fall out. I want to use my deck another 10 years and then sell the boat (HR352 #375 from 1984). Every year I replace some caulking rubber (I buy one 300 ml tube per year and use it up right away, the stuff will not last long once opened) and this is my simple procedure. 1. Remove the loose old rubber. 2. Cut half of the deeper wood in the goove away under a 45 degrees angle with a sharp chisel, to deepen the groove without making a large opening to the deck. 3. Apply masking tape on either side of the groove. 4. Clean the groove and apply the caulking primer and let it dry. 5. Apply new caulking rubber, seeing to it that it extends a bit above the wood surface. 6. After hardening remove the masking tape and cut the rubber to size with a sharp knife.I only do the loose rubber sections and if I live long enough one day I will have done the whole deck. The treated parts do not come out any more, so that's good.