In this project we approximate the water-containing, semi-permeable, canvas bag (known as a Lister bag) by a “lumped capacitance” model. We then use standard forced convection correlations for a cylinder in crossflow to find the sensible and latent heat transfer. The latter is associated with evaporation from the damp outer surface of the bag. With this information we predict the temperature-time history of the water as a function of atmospheric conditions including wind speed, air temperature and relative humidity. In this project we make extensive use of the air-water property spreadsheet in HTT.