Not sure this is what you want to do (those ropes, do seal by deforming to the surface, that is why they use graphite but you have to hold some pressure on them)  movement of the deck seam will relocate some of the strands that are not bonded, over time and thus a potential leak.

Also if the epoxy does not fill the rope, you will have some of the graphite in a sliding phase, which may not be so good and allow the relocation.  

fiberglass with filler like 404 = cutup tee shirts may be the cheapest answer for fill, if you put a couple of layers of glass over them. 

and lastly if you can open the seam and inject just epoxy between the top and bottom flange before re tightening it you will gain some strength on the seam it self.

Best of luck

Norm