Metacentric height is defined as GM = BM - BG. It's sign depends based on the conditions:
1
It is positive when G is lower than B It is negative when G is higher than B
2
It is positive when G is lower than B And neutral when higher than B
3
It is positive when G is above B It is negative when G is higher than B
4
It is positive when G is higher than B It is negative when G is lower than B