(2) Improvised heater. When standard items either are not available or are
insufficient in number to heat water properly, necessary devices must be improvised.
Improvised methods of heating water in the field are described in subsequent
6-26. FIRE TRENCH
When solid fuels are plentiful, their use in a fire trench is one of the easiest
methods for heating water (figure 6-20). The trench should be about one foot wide and
one foot deep. Its length will depend on the number of water cans to be heated. For
three cans, usually a trench 8 feet long is sufficient. The cans, supported by steel rods
and pipes, are placed over the trench and the fire is built in the trench. This method
uses a great amount of fuel and should be used only when wood or coal is abundant
and a more efficient means is not available. If used for heating messkit wash water, the
fire must be constantly attended to assure that the water in the second and third cans is
kept boiling throughout use. In addition, cans are set near one side of the trench so
users will not have to reach across the flames and possibly burn themselves.
Figure 6-20. Messkit washline setup with fire trench.