I've also read Further Offshore by Illingworth which contains his side of the story as an aside in a couple of pages.
Interesting - will need to have a look.
Chichester asked that the keel be changed from a short deep one amidships
, and it was extended back to the rudder. I assume that 'short' means a small chord. Was it this extension which caused her to either gripe up to windward, or fall off to leeward depending on the angle of heel - within a few degrees of a critical angle.
Chichester also wanted a bigger sailplan for light airs - provided through big genoas.
GM IV seemed very tender, even after cutting out bits of the deadwood, and adding 2,400 lbs of lead.
I don't know what her ballast ratio is - don't suppose that she has a lot of form stability.
Will need to read some accounts of her recent voyaging - how many changes were made during her refurb?