[dmos62]

I think you're misremembering the part with the signs. The guy came up with the idea to look for a sign on the beach that forbids anchoring. They found it and the cable proved to be there. Source: https://en.wikipedia.org/wiki/Blind_Man%27s_Bluff:_The_Untol...

[pardavis]

It sounds like you're right. Also, that's the book I read way back then! Neat, I'll have to pick it up again.