An alternator gets hotter the more it works.<br /><br />Your alternator charges more when your battery needs it. After cranking etc. the batt. voltage is a little low and alternator does it best to restore the level.<br /><br />It is normal and temp. may even get so that you can't hold a hand on it. It should, however, get colder when charge decreases.
If your ever out on the water and your motor all of a sudden shuts off, and you go to restart it and no juice is coming out of the batteries for your starter, your Alt. is bad. Just like your car, an Alt. is always gonna be hot after being driven.
