Drilling Holes?? Carefully plan your installation before you perform an installation. You know what they say, Measure twice, drill once! Before proceeding to drill check carefully to ensure that the hole will not affect the operation of other equipment in close proximity, nor compromise the integrity of the structure.
Before drilling holes mark the position. It is good practice to use masking tape on the surface to be drilled then drill the hole through the tape. This will avoid scratching/chipping of the surrounding surface. Then, with a counter sink bit, lightly counter sink the surface. This keeps spider crackes from forming after the bolt or screw is tightened down. After drilling and counter sinking the hole(s), apply a marine grade sealant (3M 5200) to the cut surface to ensure it is completely sealed against the ingress of moisture between lamination. Clean any excess sealant from all surfaces. Allow sealant to cure.