Hi Eamonn:

I can speak to the "in a marina (spider web of lines" idea.  DON'T DO IT!!!!  I was in Puerto Del Rey marina during Irma and Maria (cat 4 & 5),  Boat stripped, spider web of lines (11), many doubled up,  many many fenders (14) (tied to dock and the boat).  Liahona survived but was damaged.  Half of the fenders weren't found, the remaining half were destroyed.  Boats on either side of me sank. YOU ARE NOT SAFE IN A SLIP NO MATTER WHAT YOU DO. Cloud Street (an Amel SM on the dock behind me had a 65 boat break free from, out dock and come down on her.  As a testament to how stout Amel boats are, Cloud street survived with repairable damage while the boat that hit her sunk next to her.

In a slip you are dealing with storm surge and wind as well as other boats and flying debris.  In PDR (Puerto Del Rey) some boats floated up over top of their docks due to surge.  You are also hazarded by other boats around you.  There is only one of this hazards you can mitigate, on the hard you do away with storm surge issues.   On the hard the boat must be strapped down onto deep set anchors.  The jack stands will fall away/be washed away, or sink in the wet ground.  Only the straps will save you.  Even jack stands welded together is no guarantee.   Many boats on the hard in PDR had the jack stands gone and were supported only by the tie down straps following the storm. In PDR they have a re-inforced concrete grid of footings/anchors buried many feet deep in the ground.  Those proved themselves.  Even a cradle is no guarantee unless it is strapped down.   

I concur that leaving a boat on a mooring in a storm is extremely unwise no matter how big the mooring.

The above is hard earned from my actual experience. 

Wish you the best, 

Gary S. Silver, M.D.
s/v Liahona
Amel SM 2000  #335
Puerto Del Rey Marina, Puerto Rico