Is there access through the v-berth in your P-15 so that you can reach the underside of the deck where the centerboard tackle is fastened? Would it be feasible to drill holes in the v-berth deck and use bolts with washers and nuts to hold the tackle instead of self-tapping screws (which I presume is what is used now)?
I am not familiar with the interior of a Mk II Potter--my boat is old enough so that the interior is wood instead of fiberglass. There is enough wood under the centerboard tackle location so that in my Potter it is held down by inch-long screws.
Regards
Tom Grimes
P-14 #363 Far Horizon
Muncie, Indiana