JUST GRADUATED UP (FROM A 22) TO 30' CAT. PROP HAS DAMAGE...LOOKS LIKE IT WAS DEFECTIVE AND ZINCS HAD NOT BEEN CHANGED IN A WHILE...ANYHOW, CAN SOMEONE TELL ME WHAT IS THE BEST SIZE/TYPE (PREFERRABLY ONE I DON'T NEED ANOTHER LOAN FOR!!) PROP FOR THIS BOAT?