It would be normal practice that, through the period of the voyage, regular checks are made on the tank ullage values and the temperatures of all tanks. Empty tanks and cofferdams, together with pump rooms, should be sounded daily to ensure no leakage is apparent. Generally, oil is loaded at a higher temperature than that which will be experienced at sea, as such it would be expected that the oil will cool and the ullage will increase for the first part of the voyage.

Viscous oils like fuel oil or heavy lubricating oil would normally be expected to be heated for several days before arrival at the port of discharge. Heating will decrease the viscosity and a higher rate of discharge can be anticipated. Overheating should be avoided as this could affect the character of the product and may strain the structure of the vessel.

Tanks are vented by exhaust ventilators above deck level via masts and Samson Posts. Volatile cargoes such as gasoline are vented via pressure relief valves which only operate when the tank pressure difference to atmosphere exceeds 0.14 kg/cm ². This prevents an excessive loss of cargo due to evaporation. Evaporation of cargo can also be reduced in hot weather by spraying the upper decks cool with water.