I have replaced broken bridal bow tangs on both nacra 5.8s and P-19s. They are shaped like a cross or a T. The "T" portion is shaped to conform to the inside of the hull where the deck and hull meet. They are glassed in. I used a hole saw with a 5 or 6 inch saw and drilled out a hole on the inboard side of the hull just across from the tang. I used it in reverse to get a good clean hole. I then used a small fiberglass removal wheel attached to a drill and removed the glass and remainder of the tang, put some mat and glass on the inside, placed the new tang in place using vise grips to hold it firmly in place, some more glass on the inside.
after it cured I closed up the hole I made using the cut out piece. I have one of the tangs and will take a picture and send it to you if you like. Hullflyer1@netzero.com