I recently had to review a chainplate on one of my COI cats and send a note to the USCG.
I see from the X-Ray report that the Aolani chainplates were not steel, but composite as I thought they were.
These composite plates are immune to corrosion, unlike metal ones.
I assume the builder used my layup schedule as I have sent earlier. I see no reason to doubt that.
They are easy for the builders to build in a huge safety factor.
Instead of being fastened onto a hull, these synergistically combine to both strengthen the hull and the chainplate.
Unlike the metal plates, these have some resiliency so make all the parts longer lived.
Any delta in the parts from the loads would show up immediately and early by cracks in the paint. Unlike metal plates which usually are not painted.
Attached find a picture of one of my other catamaran designs with composite chainplates. Note that he lifts his entire vessel with only the three chainplate locations.