Caulk and seal - a little pre-winter maintenance

We own a Ranger Tug and have identified several places, both interior and exterior, where the existing sealant is beginning to fail. For example, on the exterior where a fiberglass locker meets the fiberglass cabin side, the sealant line has fractured. Inside the cabin, we’re seeing a similar fracture where the galley countertop meets the fiberglass galley walls.

For seams like these, what sealant products do you typically recommend for recaulking? My plan was to use UV‑tolerant 3M 4200 in most locations, although I’ve used BoatLife sealant in a few areas previously. I’m open to other suggestions if you believe other products are better suited for these types of joints.

Additionally, in the main head, the silicone caulking around the shower pan has failed in one small section. I’m debating whether the entire seam needs to be removed to address this, which would be a significant job and risks damaging the sole during mechanical removal. I know silicone generally does not adhere well to itself, but I’m hoping that a marine‑grade silicone might be sufficient for repairing this one‑inch section without removing the entire bead. I’d appreciate your input!
Thank you.

After many years with a fiberglass rv and an older sailboat, I won't put silicone anywhere but kitchens and bathrooms.
In the head, I'm undecided.

I rebedded all my hatches this summer after dealing with a soggy headliner. Sikaflex 291 all around.

It was striking how easily they came off, much of the original sealant was not bonded to the frames anymore.