[163233]
...
Why would I want to change a serviceable item ?
Think on this : Ships not only have large valves and seacocks .. but also many small ones ... they do not change every 5 years - in fact vast majority of them go the life of the vessel in far harsher conditions than your boats ...
5 years sounds a touch short, but when we had our boat surveyed last the surveyor - hardly a gorilla - managed to rip one of the seacocks off the through hull with his bare hands. Fortunately while on the hard.
They don't last forever. The boat is only 15.