I'd want floorboards
I'm not sure if floorboards were standard on the Mariners at that time, I know that the new Stuart Mariners don't seem to have them. You might want to give Rudy Nickerson at D&R Marine a call (508) 644-3001, he has his shop up in Assonet, MA and was the Parts Dept. Manager for O'DAY for mant years. If floorboards were available, he will know. I'd actually suggest visiting him on a Saturday morning, he is a great source of info and has helped me on a few parts that I've needed for my Day Sailer II. It is times like this that I wish that I still had the 1970 O'DAY sales brochure that showed the Mariner 2+2! My parents looked at a Mariner before buying our CAL 21 in 1970. The CAL 21 does have floorboards in the cabin, and it is nice to have a dry, level area to stand on. You really won't do any harm walking on the bilge of the boat (I think you are actually standing on the molded-in lead ballast) but it is a lot nicer having floorboards.Oh, one question, is your boat the light green Mariner moored in Broad Marsh River, or the one moored off Hamilton Beach? I assume she is not the white Mariner off Hamilton (newer model). I moor my DS II in Mark's Cove, you can't miss her, she is bright yellow! Our CAL 21 is at ZECCO Marine, presently for sale after 38 years in our family. Dad enjoys sailing our smaller boats more now and the mooring at ZECCO is not cheap.