Shiva has a teak rub rail which is set over the (raised) deck
to hull joint. The hull is not aligned at the joint... the upper deck part is proud / over the lower hull. The original rr was riveted and set on some sort of butyl or dense foam rubber "tape". The rivets were glassed over on the inside. There teak dead ends into a stainless steel
receiver molding at the bow and the stern. The rivets are covered by 1/2 round ss molding,
There are no leaks
at this joint.
I have had to replace parts
of the rr over the years... when it split / cracked and so became unsightly to say the least. I did the work at dockside or on the hard
from a scaffold.
I have also replace the entire rr on a sister ship for a boat yard. They had the boat inside and scaffolds and ordered the profiled teak from the mfg. I scarfed it and screwed it with ss screws. This CAN leak if the screws punch through the fiberglass
on the interior
The deck to hull joint likely does not depend on these rivets...they simply hold the rr on.
I purchased 6 - 14' long 2"x3" planks of teak to replace the existing. I have been debating how to do this for 5 years or more... But this may be the Spring when I tackle it.
The options are:
1. Remove the existing and replace with new... milled and it would be actually a much larger finished profile. Existing profile is 1 1/4"d x 2"h Use new butyl tape or similar caulk. Fill in all existing holes with epoxy
2. Mill the existing rr in place (yikes) and profile the new 2x3 so it fits over with the old being a "key" and then screw and epoxy
the new to the old. Much of the 2x3 would be removed and it would make bending it easier. Scarfing would be a challenge!
3. Mill the existing rr in place (yikes) and then cut the 2x3 into "strips" and epoxy the strips over the "core" and with minimal screws and mostly held by clamps, profile in place with a router... add the old or new ss strip.
#2 and #3 will not put a 100 holes in the joint through the hull/deck fiberglass
which will inevitably see water
getting at the screws! YUCK.
#1 might be the simplest... but will involve 100 new holes through the hull/deck fiberglass which will inevitably see water
getting at the screws! in addition to the old rivets which required to be cut off and sealed over properly. #1 makes for a more attractive termination at the receivers with #2  a veritable bitch to do a clean looking job. But # 1 will have probably the most robust rr and the better looking joints and grain.
I have lots of design drawings for this project! That was not hard.