on the front crank wasn't a good thing after the second seal. When I had the engine rebuilt in Puerto Vallarta in '07 I changed back to my two alternators. They both have electronic regulators and I leave the port one un-plugged so the alternator runs without load as a backup. If I loose the starboard alternator I can just unplug it and plug in the port one. I could completely take off the belt but it's nice to have a quick change option. I have to admit that it's only happened one time in the last 10 years so it might be a bit over kill. Having said that, it was in the middle of the night motor sailing into shitty weather 200 miles up the coast from Mag Bay on the outside of Baja California. So the question is, is it overkill or not? I normally run with only the one alternator with the batteries already charged up by the solar panels and wind generator. If I wake up in the morning, I'm usually about 80 amps down on the batteries from the TV, DVD, refrigeration, freezer, anchor and cabin lights so the one alternator brings it back pretty quickly if I have to get up and go. Alternators have given me some pretty funny stories over the years. 25 or so years ago I lost my alternator in some backwater place in Costa Rica and only could find one from a auto parts shop a half a days ride from where I was. I bought the only one they had that I could make fit but it happened to be a 100 amp alternator. The problem was that it was a 13 horse power engine. It charged the hell out of the batteries but I had to put a disconnect switch in the field winding wire so I could turn it off if I had to move the boat. Either/or. Charge the batteries or move the boat. I lived like that until I got to Panama and could buy a 65 amp.