Carl,
I agree the the proposed solutions are getting complex, but I think Gary's correct in pointing out that the channel molded into the hull is flexing, and I think that this is what's allowing the bolt rope to escape, not that the bolt rope is shrinking in dia. I have this issue on another boat, and I increased the bolt rope dia, and the channel just opened up more. But I do need to inspect the channel closely to see if I can confirm that the groove is indeed opening under pressure. Thanks for your input!

Dave