Good info on the West link.
And should I get 4 or 6 just for "permanent" tie up?
To answer this, I personally use 8 for everyday use. Plus we carry an extra set for transient purposes. If we are expecting heavy weather we will add to the 8 as required.
Courtney is My Hero
If a man is to be obsessed by something, I suppose a boat is as good as anything, perhaps a bit better than most - E.B. White