|As you probably know, when the builders joined the deck and interior liner, they bonded the two with gobs of polyester putty. This, in many cases, often creates an impassable blockage to wire-feeding. Sometimes you get lucky, sometimes you don't. I tried for ages to force a path with an old fish-tape with the end cut off, but had to admit defeat and run the wires on the inner surface. That's all I can offer by way of consolation - you're not alone here.
C&C 27 Mk IV