My 1986 Newport 28 MKII has a slanted
fiberglass cabin sole and it does not flex. If the one you are considering has a flat
teak and holley floor, it could be rotten due to water
leaks or the cabin sole was under water for a while. I would
lift the
bilge access panel in the cabin sole and look/feel around the underside of the sole for rotten
wood or loose cabin sole supports. The supports could have rotted. I have been on several N28's with the
teak and holley cabin sole and they were all solid, no flex. The bigger issue is did a lot of water get into the
boat from a partial sinking, etc. Look at the bulkheads (vertical
wood walls)mast support and lower cabinet doors for staining from standing water that might have covered the sole. Probably worth having a
surveyor look at it if you are not sure about what you find. Feel free to PM me if you want more info in the N28.
Steve