View attachment 326793
View attachment 326794
Here is an example of using chop strand for finishing. I only wet out the area I need it to bond too and grind the excess off after it cures. The second pic is after using a air grinder with 40 grit.
In your case, I'd hit the back with a air grinder fitted with a 3 inch 40 grit disk to smooth out the entire surface . I use a 3 in disk on a 2 inch base so the edge of the disk is flexible. 3m roloc is the name of the disks I use.
Then i'd cut 2-3 pieces of 3/4 oz chop strand mat bigger than the entire back of ski. Loosen them up a little by rolling them up.
Wet out the back side of ski, lay a layer of mat, wet it out, lay 2nd layer of mat, wet it out, etc.. Let the excess hang off all the edges, wetting out just a little further than the edge. Cover with one large piece of wax paper and roll out excess resin and air.
Once cured the wax paper will peal right off leaving a nice smooth finish. Take the excess that's over hanging the edge off with air grinder, leaving a 1/4 in or so. Finish the edges by hand for your final shape and hand sand the rest of the rear for a finished smooth surface that will need very little filler.
This will tie in the edge of the hull to the edge of your work so far leaving a nice seamless transition, giving you a smooth edge oem look.