I had "almost" the same kind of connection break on my boat.
I didn't have the flange on the end it was just right flush with the gunnel and bolted from underneath.
I could not get to the bolt and I found rail brackets online with the exact angle I needed. Three screws fasten it to the boat and set screws hold the rail. It is stronger than original.
But for yours you would have to cut/grind off that flange.
Something like these they come in different angles. I actually did the side that was still intact so they would match and the added strength. People are always yanking on bow rails.
60° Round Base S.S. Boat Rail Mount, 7/8" #6040C
https://www.easternmarine.com/index....FVOe4AodMgkAzw