Mine is an 85 Hobie 18. The main crack is on the inside of the starboard hull (foward crossbar), although all the others are showing slight cracking to spider cracks. Luckily the hatch is right next to this crack so access problems are not as much of an issue. By the metal plate reinforcement do you mean the "u" channel washer type plate? Because all 8 locations have these. But the cracks start a little beyond these plates. I will look for that old thread on this repair

Thank you,