I wouldn't sand your paddle down ..specially if its a good carbon one .I would buy another one ..maybe a 8.0 vario .when I'm on a longer board in still water,i use a longer paddle .in surf a little shorter depends on how choppy .You can paddle a bit faster with a smaller Paddle .but loss horsepower .I'm 95 kg and use a 8.5 naish vario .And in the surf I've cut a makani to size .as I don't like the vario's in the surf ,cause they take on water .if you get a vario you can experiment ,and see what works for you .If your paddle feels too long and big it probably is .