I have often had loose rivets in the rear corner casting. Replaced them many times with stainless ones but still had them loose after not many hours sailing.
At a certain time I noticed that the rivets on the forward corner casting were always good and my understanding was that the dolphing striker was helping to keep the three pieces (left corner casting-crossbar-right corner casting) together.
I have then added a wire between the rear left corner casting and right one as the referenced pictures show (you have to follow the three links to see them, I couldn't embed them in the topic because they have no "jpg" extension).
I wanted to ask opinions here about this idea, Especially:
1. I wanted to understand whether this solution can really help or it is useless.
2. I am worried of adding tensions that could solicit the structure in an unexpected way.
Any other comment is welcome.