I'm not fretting at all. It's going onto the my launch with the boiler. It's 22 lbs altogether alternator and stuart. The visual interest is excellent, it's a good demonstrator for those who think steam power is complete magic (which it still isLopez Mike wrote:I wouldn't fret a bit about the efficiency of your alternator.

This is a case of why I like Bill Durham's attitude in his steam boat bible - there is enough water for all types of configuration of launches.
And in that vein I thought I'd just share my solution to a little bit of steam electricity as I was putting it together.
-CB