On my Hunter the sidewall fabric was a dingy gray carpet that over the years got wet, held mold and mildew, etc. Looked horrible over the years we owned the boat. One day we decided to pull out all the fabric sidewalls and installed 1/2 foam against the hull for soundproofing and plastic sheeting (1/16 inch thick) with adhesive and it now looks like a new boat interior. Bright white side walls and it cleans easilly and doesn’t get the mold or mildew anymore.
Here is the before for the aft berth:
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And here is the after: