Tapped and bolted Too
On a H40.5, I installed a Garhauer Rigid Vang and used 1/4" bolts. Ditto on Steve's install, only I used the existing mast fitting where the soft vang attached. I had to drill it out slightly to make the new bolt fit.I have put Yaga through some very tough conditions over the last 3 years and put the vang to the test. I just inspected it this weekend and everything looks and fits tight. Machine screws let me remove them to do a close inspection.The boom fitting has screws on both side so they would have to rip out sideways. I did not see any signs of movement of the fitting.