Again, it depends on how much time, money, and perhaps learning you want to invest.
Royalex is a sandwich material. The structural part is ABS plastic, but the ABS is in three layers: a “foam core” with a solid layer of ABS bonded to each side. The foam core renders the specific gravity of the hull less than 1.0 so it won’t sink, and it provides rigidity.
Bonded to each side of the ABS component is a thin layer of colored vinyl. The vinyl protects the ABS from UV degradation and is cosmetic. It also makes it easier to bond outfitting into the hull using vinyl adhesive.
In your boat the blue interior and exterior is the vinyl layer. On the exterior, in the high wear areas of the chines and stems, a good bit of the vinyl has been abraded completely away exposing the light colored ABS. It also looks as if there are several areas in which the outer solid layer of ABS has worn through exposing small areas of the foam core. It is likely that around these areas of exposed foam core, the remaining solid layer of ABS has been thinned out.
If you are willing to invest somewhere in the neighborhood of $80 or so I would start by removing what is left of the crappy Kevlar felt abrasion plates. Felt materials consist of compressed, short fibers and even Kevlar felt is relatively weak because there are no long fibers running through it. It is very common for Kevlar felt plates to break off in big chunks as yours have. You may be able to take the remnants off with a chisel or you may have to take portions off with a power sander. You will generate lots of dust so wear a mask and work outside. Try not to take off too much ABS along with the Kevlar felt.
Next, I would sand the entire hull bottom removing any loose pieces of vinyl that are bound to come off anyway, and smooth the edges of the vinyl that remains well-attached. Later you will want to paint over the exposed ABS to protect it from UV exposure.
After cleaning up the hull, fill in any voids where the foam core has become exposed. Personally, I would use West System G Flex epoxy and I would specifically get the 650K kit shown here:
This is available from many vendors. Don’t worry that the package says “Aluminum Boat Repair Kit”. This kit comes with 4 oz of resin, 4 oz of hardener, some colloidal silica powder to thicken the epoxy as needed, some mixing tools, and etc. Mix small batches of epoxy by mixing hardener and resin 1:1 by eye. For filling in the foam core I would thicken the epoxy by stirring in silica powder. Apply the mixture to the voids and let it settle in. You will probably need to make more than one application. When the voids are fill sand the cured epoxy fair and flush.
I would also by a yard or so of either 6 oz/sq yd fiberglass or 5 oz/sq yd Dynel plain weave cloth. You could use either to make new abrasion plates to cover the stem wear areas after removing the old Kevlar. If you are interested in doing this send me a PM and I can give you more detailed instructions on how to proceed. If you are careful not to waste epoxy, a single 650 K G Flex kit will probably be sufficient to apply a pair of abrasion plates and fill in the voids where the foam core is exposed.
Finally, if the vinyl is intact on the hull sides, I would probably just wash the boat up and paint the hull bottom up to a 4 inch waterline. You can paint the whole thing if you wish, but that will add a bit more weight. Just about any spray paint will do. You will need a couple of cans even if you just paint the bottom. A lot of people use Krylon Fusion which Krylon claims to be formulated to better adhere to plastic. Valspar also makes spray paints formulated to adhere to plastic.
If you want to brighten up the aluminum gunwales some, go over them with some very fine steel wool.