I’ll clean up the rail and see if I think I can make a good repair. The grp (polyester) I plan to attack with hammer and chisel, chop it back to good laminate and cut away the external “bulging” that has deformed the exterior and cracked through gel coat. Treatment with epoxy to seal and then make good with premixed epoxy glass paste. Fine filler on exterior and finish with same colour gell coat. Think it takes another few half days.