if you go via cranbourne, bass, wonthaggi etc, stop at inverloch. u may find there's no need to go any further unless u dead keen to sail sp. if u keep going u need to take tarwin lower rd, buffalo rd to fish creek, or dunlops and stewarts roads across to waratah rd, but they are a bit dodgy. be aware there are a few roads in that area with similar names that catch peple out. whoever named them should be flogged

otherwise as drjukka said, go via fish creek via sth gippy hwy. its a lttle more pleasant
sailing vic in summer is tops

if u get a chance to sail venus bay it is worth a look. nothing like it in se qld