Fishing line and rudders

My dad and I took the Hobie 18 out near Cape San Blas, FL at Indian Pass. We've been the only sailboat out here so far, most every other boat has been fishing. We had some fun, got to sail amongst a group of dolphins (the dolphin striker did not live up to its name, thankfully). I could almost reach out and touch one when I was out on the trapeze. A little while later, we noticed that the rudders had started dragging a line. We flipped them up and tried to detangle, but to no avail. By the time we beached it, the line (what we found to be a shark fishing line, with the heavy duty monofilament line, steel cable, and big hook and a red snapper for bait) had sawed about 1 inch into the rudders. These are the solid white plastic rudders. What's the best way to repair this kind of damage?

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1987 Hobie 18 Magnum, white with Cat Fever (and Blue Hawaii) sails