Accurate temperature recording is crucial when detecting bunker fuel concealment because the same mass of bunker fuel will record a slightly different volume at different temperatures.
Verify the temperature on the surface of the sounding tape just before it is being pulled out (this may not be very accurate but will give a general idea of the average tank temperatures).
In case of unusual high temperatures reported by the chief engineer, attach a manual thermometer to the tape bobs to ascertain the exact temperature.
Investing in a good digital thermometer may be worthwhile. These can be dipped directly into the tanks through the sounding pipe.
Note the body temperature of fuel oil transfer pumps before and after the soundings/measurements to eliminate any transfer of fuel oil and / or re-inspecting engine room tanks after completing the soundings.
For this reason it is advisable to start the soundings of the tanks located on the deck and working your way to the tanks in the engine room.