One method of re-coring is to remove the bottom laminate and core from the underside. This leaves the deck non-skid intact. Yes, upside down laminating is not pleasant, but can be done.
After removing the old core from underneath, you can replace it with Balsa or any other core. Core materials are very light and with epoxy, heavily thickened with fumed silica (Cabosil/Aerosil), it is not difficult to stick the new core to the old top laminate. For large areas, you can do a square foot or several square feet at a time and prop in place, if necessary, with a thin sheet of plwood, waxed or covered with Visqueen.
After the thickened epoxy has set up but is not fully cured, laminate over the new core with at least two layers of 1708. 1708 is a biaxial with a stitch mat(no binders). Wet out the semi-cured new core with a good amount of epoxy using a 4" or 7" roller, then apply the glass, wetting out the glass and keeping it in place till saturated. Once fully wet out it will stay in place and not come off. Just in case, keep an eye on it and be ready to catch it before it sags.
One more tip, for better wet out, heat your resin before mixing. I have successfully laminated with US Composites epoxy heated to as high as 120F. I use a cheapo digital meat thermometer, stuck into the epoxy jug.
Obviously, this type of repair only is applicable to boats with a removable headliner.
Last edited by pmcguire; 05-20-2011 at 08:18 PM.