Rub Rail Repair Method
I've recaulked rub rails on 3 O'Days - 1984, 1985 and 1989 vintage, and all three had a 2-part rubrail: 1. an off-white plastic extrusion, and 2. a "rubber" (really a black vinyl) strip. The white part was screwed to the hull/deck joint every 4 to 6 in. The black strip snapped into the white plastic base, to cover the attachment screws and serve as the "working surface" to absorb impacts. I'm unsure about the design of the rubrail on your 25, but for the design described above, here's the method that worked well:The first step is to unsnap the black vinyl strip. It's easiest to do this when the vinyl has been warmed a little by the sun. Use a 1 in. wide putty knife to get it started. Start midway along the gunwale and remove either the forward of aft half along the boat length. Then at the point 1/2 way from bow to stern, carefully saw the white extrusion. Use a very fine back saw. The thinner the blade, the better in order to minimize the width of the cut. Now proceed to unsrew the white extrusion as far forward or aft as the black strip has been removed. Check the hull-to-deck joint while the strip is loose. Recaulk whatever needs it with a polysulfide caulk. I use life caulk. After the white extrusion is remounted, snap the black vinyl back in place. Then repeat the whole process in by working in the opposite direction. Treat the stern the same way. There will probably already be a joint or ends of the white extrusion, and therefore you won't need to saw it.The key here is to keep most of the vinyl and white extrusion in place, so that parts don't stretch, but stay in line for reassembly.