Keeping a close eye on temperatures of things mechanical could forewarn you of problems and potential breakdowns. The engines are equipped with gauges which can be monitored and I believe they are equipped with audible alarms as well. An option for measuring ER temps as well as prop shaft temps is to use a remote temperature sensor with the display at the helm.
If you wanted to get elaborate you could attach one of these sensors to A/C and fresh water pumps. One unit I have found, and it’s relatively inexpensive, is the Minn Kota Fishermen’s Temp Sensor. Its range is limited to -58 F to 158 F. It also stores max and min temperature ranges. You can find it here:
http://www.shootnhunt.com/catalog/JM/gauges_instruments..._gauges/5101997.html

Check out this updated temp sensor:
http://www.cabelas.com/cabelas/en/templates/product/sta...n%20Kota%20Fishermen's%20Temp%20Sensor&cm_ite=netcon&hasJS=true