"Eddie E" wrote
Thank you very much for the replies.
the fin thing (sorry I don't now the proper name)

skeg

And like most everyone else said, if there's no more to it than that little
bite missing, it's probably not going to have any noticeable effect. If it
was mine, I'd grind/file it down to a more pleasing shape: sharp edges are
attractive to the galvanic currents that cause corrosion. Speaking of which,
if you plan to have your boat in the water for any continuous length of
time, you might want to get a good coat of paint on there.