Originally Posted by massnspace
My question is about the galvanization. What will happen? What’s underneath the galvanizing, just mild steel?
Underneath the galvanising is high tensile steel. It will certainly rust if you grind away a significant portion of the galvanising, although the adjacent intact galvanising will act an anode, so the rusting will be less than you may otherwise expect.
Make sure you wear appropriate PPE. I believe grinding galvanising is quite hazardous.
It would be nice to know where you plan to modify the shank. Overall, removing shank material is very unlikely to reduce the performance of the anchor. Anchors such as Rocna benefit from the minimum weight possible in the shank, hence the use of fabricated shanks (Spade, Ultra) or specially profiled shanks (Rocna MK2) to reduce the shank weight. Therefore, if anything, the modification is likely to increase the performance rather than reducing it.
However, you will be reducing shank strength. The reasonable number of bent shanks Rocna experienced with only a modest reduction in shank strength (due to the wrong grade of steel) shows that there is little practical leeway. A bent shank is a real possibility of only a slight reduction in shank strength. The most critical factor is horizontal strength. Be particularly careful about small notches that will create some stress concentration.
Obviously, you will invalidate the warranty.