1974,
The black rub rail is flexible PVC. I'd just fill the slash with black silicone and call it a day.
The black rub rail holder sits in the white "rigid PVC rub rail holder". This is the piece that is broken up. You could try rebuilding it with something. I think I would try G-Flex epoxy with a thickening agent used to get it stiff as peanut butter. G-Flex will stick to plastic/PVC.
If you want to replace it go to
D&R Marine has it. That link should take you to their page where they list it for the O'day 22.
FYI, that white rub rail holder is screwed over the hull to deck joint. It covers the screws that hold the joint together. Here's a pic of it on my 1980 O'day 25 where a piece was missing.
I purchased a few feet from D&R and replaced the damaged section. I also found several of the screws in that area were loose and allowed rain to run into the holes and into the boat. I took at the loose screws, filled the holes with thickened epoxy and put the screws back in.
You might have the same thing until you fix it.
And yes, your hull is fiberglass. Previous comments were talking about the plastic rub rail holder.
The damage to the red area is dock rash. (IMHO) Unless you want to fix it for cosmetic reasons I wouldn't bother. If you do you could get some epoxy fairing compound to fill and smooth the area. You won't match that color but maybe a contrast colored stripe down the bow would look better than a patch.
im more worried about the slash.....
Then just fill with some silicone or rubber sealant.
Regards,
Ward