Bolting / Sinking screw into a nida-core panel
 

This page shows how to reinforce a nidacore panel so that it can take screws/bolts . . . basically says to fill the area that will be receiving bolts with a polyester or epoxy putty before you laminate the side. Looks promising!!

http://www.protechmarinecenter.com/n...e/Repairs.html

Re: Bolting / Sinking screw into a nida-core panel
 

Here's another webpage on that subject.
http://bertram31.com/proj/tips/sleeving.htm
I used both methods. In the transom I used PVC tubes where heave stuff will be mounted.
Where small pieces like wiring will go thru I filled it with epoxy putty.