Not aircraft related, but help still needed. We need to lighten the weight of a large aluminium workboat that has a 18mm marine ply floor that is 9.72 kg per square metre. One of the ways that we have identified to reduce weight is to replace the marine ply floor with composite panels we make. Obviously the floor of a diving workboat takes more of an impact pounding on a daily basis than a plane (dropped weight belts, dive cylinders etc), so any suggestions on what materials to use? We can get all the usual composite materials, and for the core material either balsa, honeycomb or foam might be an option.