Take the seat off and anything that will keep it from laying upside down unevenly (rod holder mounts etc).
Put some blankets, towels or drop cloths on the Driveway or Garage floor on the ends and then Flip it completely upside down so it sits "On an even keel" & then Wet sand the deep gouges with 800-1000 grit emery cloth then rinse well so you can get any grit out that got embedded in the plastic.
Make sure you have got good light and no wind or breeze and then break out a hand held propane torch (home depot, lowes or true value or even harbor freight has them).
Start very lightly keeping a good distance from what you want to smooth out and Slowly work the flame closer to the hull. Focus on the distance from the tip of the torch and watch the color of the flame and the sheen of the area around the flames contact area on the plastic.
As you go take the time to change you angles of view on the area you are working on and shift the light if you are using a drop light. ...You do not want any excessive smoke!.
It's all about being methodical & slow but be Very, Very Carefull!!!
So you do not burn a hole through it!
With a little practice and a gentile touch you can make any Plastic hulled Kayak shine like a Diamond in a Goats Ass using a hand held propane torch
