A bit unpopular down at the duck pond because of the noise, heat and speed.
http://www.beck-technologies.com/freeplans.htmlGo to the homepage, a good read for a couple of hours.
333 - Once you get to know us a little, you will get access to the plans section, where there are a few bits to try out with reference to steam, and I am sure if you ask the right questions, you will get all the answers you will need.
Single acting, double acting, slide valve, piston valve, oscillator? Vertical or horizontal, single or multi cylinder?
As you can see, steam comes in all flavours (and there is more of the above). I would suggest, type of boat and size you want to make it, or if you just want to make a steam engine, big or small and what do you want it to do.
Sorry to be so offhand and vague, it isn't meant to frighten you away, but a clue like I have suggested, would help a great deal towards us trying to help you.
John