- Minimise Free surfaces
(Having sounded all the tanks any that are slack will be identified. Minimise the loss of GM due to free surface effect by topping up low down ballast tanks and transferring fuel as necessary. This action alone may remedy the situation.)
- Ballast tanks low down in the ship
(Select a set of suitably subdivided double bottom tanks to ballast. ideally start with tanks that have the smallest free surface areas to minimise the effects of free surface whilst filling. The order of filling is as follows and must be strictly adhered to:
- Start by filling the tank on the low side (No. 1) as shown. Because of the introduction of more free surfaces whilst filling the first tank the situation will initially worsen.
- When the first tank is completely full, fill the centre tank (No. 2).
- When the centre tank is full, fill the final tank (No. 3)
- If G is lowered sufficiently then the ship should complete in an upright condition (having initially verified that the port and starboard moments were the same).
The movement of G after completely filling each of the tanks is as depicted in figure below (ignoring the upward movement of G which arises as a result of the introduced free surface at intermediate stages of filling the tanks)
If the situation is not remedied then a second set of tanks must be chosen for filling, the process is repeated.
