Just be be clear here when referring to 304 stainless steel, it contains chromium (min. 18%), and nickel (min. 8%). It is an austenite steel and is only slightly responsive to magnetic fields.
It also contains 18 – 20% chromium and 8-10.50% nickel, and lesser quantities of some other elements.
Where as 316 grade stainless steel is a molybdenum-alloyed steel. The fact that it is also negligibly responsive to magnetic fields
means that it can be used in applications where a non-magnetic metal is required. It also contains a number of other elements in varying concentrations, making it a preferable material for marine use,
What is see more often is Galvanic corrosion forming around two dissimilar materials such as SS with wood/rubber/Aluminium/steel/brass/bronze etc,
Strangely enough I find numerous boat owners that have never heard of Durolac
Duralac is an anti-corrosive jointing compound for use between joints of dissimilar metals. It is in the form of a tough, flexible, yellow paste with low moisture permeability, and contains barium chromate in an inert filler matrix. The barium chromate is only very slightly soluble in water, so it remains in the joint, even in the presence of a considerable flow of water. It has a long useful life because it only becomes active in the presence of conditions which promote corrosion.
• Indispensable for the effective sealing of joints between dissimilar metals --- even very active magnesium alloys
• Effective at preventing corrosion at stress contact points in similar metals, such as rivets in masts
• Protects metals in contact with non-metallic materials such as wood, resins, rubber, etc.
• Especially useful in saltwater environments which exacerbate corrosive processes
I have used this on mast fittings /rivets/bolts/wood and numerous other applications such as gaskets and even thread locking resulting even 10 years later there's no re action to dissimilar metal situations, I refer to it as a Zinc Anode paste
and out performs(IMHO) other similar products such ac Tef Gel/Lano-tech etc.(Every boat owner should a tube in there tool box)-No i have no affiliation with them- just works !! end of story
Found here: https://www.fisheriessupply.com/sadd...nting-compound