sealing the core,as certain equipment is installed is a very important step,most owners skip-rod holders installed in the cover boards,these are an excellent example-the hole for the holder goes through a cored surface-the cored surface,be it either wood,or composite,needs to be properly sealed,to prevent water intrusion-polyester based resin,is a poor choice for this-epoxy ,being waterproof,is a much better choice...
as for me,deck hardware,thruhulls,etc,3m 5200-there's a common mistake made by the inexperienced,3m 5200 is permanent,untrue ! over the years,i've installed numerous equipment on customer's boats,bedded in 3m 5200-in the case of a few,the equipment was removed,without damage to both the boat,and the equipment.i've removed many transducers,bedded in 3m 5200,gunnel caps,rod holders,etc...
here's some more information on this very subject,it's one of my facebook pages...
http://www.facebook.com/?sk=lf#!/pag...ce/71018074689