Re: Partially filling a void
Filling the void can be hit/miss and still have future problems. Better to do as recommended earlier - unbolt the traveller (probably 3/16 or 1/4 holes, same as a hole saw arbor), use 1" hole (larger if neccesary) saw to drill through liner from bottom, rebed traveller with butyl & insert shorter bolts (so they no longer pass through the liner) using fender washers to spread the load. Alternately, if you have access, fabricate an 1/8" thick aluminum back up plate the length of the traveller, drill holes in back up plate slightly larger than bolt diameter, slide plate between deck & liner & bolt together (if limited access you might cut the backup plate in half and each half in from either side. Cosmetic caps to fit holes or teak (or acrylic) cover plate to fit across bottom of liner to pretty it up. The liner shouldn't be structural in this area.