When I took the earlier photos I shamed myself into re-sealing my reinforcement plate also. this required drilling out the rivets and then re-riveted the plate. so anyway..... wile I was there I took more photos for y'all
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because of the geometry between the single mounting bolt, the point where the forestay attaches, and the installed forestay itself, there's quite a lot of force exerted to the rear side of the slot the chain plate sets in by the tensioned forestay. note the chainplate angle is almost vertical as shown by the yellow arrow shaft. this makes the reinforcement plate very important to keep from elongating the slot in the fiberglass.
When I installed my bow sprit I built a new chainplate to gain an extra 1/4" around it, but the OEM piece was actually almost identical to the one shown. as you can see, there isn't much opportunity to add another bolt to the bottom of the chainplate, and any leverage advantage really wouldn't help much regardless. which is why your reinforcement plate needs to be made secure again to support the load.
oh.. and BTW. the fiberglass under the reinforcement plate is VERY thick. if you plan to use rivets you'll want 3/16" rivets at least 3/4" long. 7/8"+ would be even better.