Hi to all:
I am wanto to change the floors of a 1979 Bertram 38 from Wood to kevlar honeycomb.
Any sugestions on what to use?
Thanks and have a great day.
Why?
I would suggest corecork for flooring. Easy to use, sound/vibration dampening, doesn’t delaminate when dented, and returns to allmost original thickness.
I would only use kevlar honeycomb when building very light, or if I could get it for free 
Aramid core is a pain to work with. Nomex will be cheaper and easier to deal with. Composite floor boards are very common on racing yachts. I’ve priced it out for a few projects I’ve done replacing floor boards on 50+ foot boats and the easiest path to follow is to by pre-made sheets and back fill and cap the edges. If you aren’t already setup for making honeycomb panels the cost of materials/chance of failure is quite large. You can also go with a 5lb/ft^3 foam core which will be heavier that honeycomb but far lighter than plywood. Also foam is going to be easier to work with.
Balsa is good. Foam works. Kevlar is expensive. Paper nomex is less expensive and doable as well. For a boat, make sure no matter what you use, that holes are sealed perfectly, else water will get in and damage it 
You can use nomex honeycomb cores. It is half cheaper than Kevlar
You want anything that will help with vibration and sound etc.
Nida core
Pet 3D core
Pet foam
Nomex type honeycomb will be stiff, hollow and noisy I think?
A 5mm thick Nomex honeycomb will cost you 34 USD per sq. meter…
Is it expensive?