In looking at the photo there not really much I can see to determine what happened for fact so let me take a guess at it.

I know with my 5.8NA when I replaced the main beam a few years back, it was done at the factory here in Santa Ana. The original had failed due to corrosion where the dolphin stricker rod had come in contact with the main beam. When I picked it up, I had noted that there was a slight camber in the beam upward. The folks at the factory had mentioned that it was important for two reasons, keeps torque on Dolphin Striker casting, and when rigged will allow for the beam to flex back to a level position, not concaved. They had told to keep an eye on that; very important, and make sure it was torque tight the first couple of time I had it out and to check it regularly. Also, they had put sleeves in the main beam it self, but from what I understand this was due to an issue with the NA rig vs. the standard rig.

Also, in on of the pixs I noted there is allot of rust on the underside of your dolphin striker. Making an assumption here, I would tend to believe that underside of you main beam or the compression tube inside the beam may have failed similar to what happened to me on the topside giving enough “wiggle room” to start the chain of events that lead to you mid-sailing breakup. Take a look down there and make sure the holes going through are not elongated, and/or the compression Tube (part#2506) doesn’t have corrosion on either end. Oh, when you do replace the beam, the only parts I would even think of reusing are the bolt plats (Part #2508) if you can get them out – other than that replace everything else.

Contact me off list c152 X roadrunner Y com (x=@ and Y=.) I may have a line on a set of beams for you – there is a 84 5.8 over here in Santa Paula with thrashed hulls I may pick up for extra parts and the trailer, maybe we can work something out on the beams.

Good luck and glad to hear your safe back on the beach