change anchor

No way, Ian!  What you generally get on forums like this is 'the sum of all our fears', so I understand it can feel a bit shouty at times -  apologies.  I see anchoring as a blend between science and art, though sometimes with a bit of luck thrown into the pot.  Always useful to learn how others manage it, except for the muppet in Mupe Bay last year who used my anchor chain instead of using his own...