|On board ship - and as long as the weather conditions permit this - the refrigerated containers are inspected at least once a day and the current temperatures are recorded manually. These records are used, in the first instance, to prove that the crew of the vessel have done their duty with regard to the care of the containers. The daily rounds are required in order to locate defective containers and to carry out appropriate repairs.
Generally the recorded temperature is the one shown as the current value by the container controller. This is usually the temperature that is to be regulated, thus in low-temperature operation it is the return air temperature and in chilled operation it is the supply air temperature (see above). Since the majority of circular temperature charts record the return air temperature (see above) the manually recorded data for a container in low-temperature mode should be the same as is recorded on the circular chart. In chilled mode on the other hand it is possible (and normal) that there are differences between the return air recordings made by hand and the supply air temperature registered by the recorder.
||Figure 42: Manually completed temperature log of a vessel
(Click the graphic to enlarge.)