The HotStuff software implements an approach to the assessment of heat stress risk on live export voyages from Australia. It combines animal heat tolerance, weather statistics and vessel parameters to give a scientifically defendable estimate of the numerical risk of mortality in each line of livestock to be loaded. It is used as a risk management tool through the assessment of planned voyages so that unacceptable risk can be avoided well ahead of the loading. This project added to and updated both the method and the software. The software is now at Version 5.0.