Well, I have provided Dancer with a holding tank under the floor forward and a head in the head. (Where else!) It hasn't been tried in anger yet, she has only been in the water once and the steam plumbing is not complete yet. It is arranged with valves so that it can be flushed out over the side whe...

I'm using steam operated drain cocks on my Leak compound. I built the engine with piston valves on both HP and LP, so it really needs good drains, and these work well. The principle is that there is a small piston sealed with an O ring that presses a valve down on its seat. The piston area is larger...

The 7.5 knots or so sounds reasonable for a top speed for a thirty foot hull. But if you are in a hurry a steam launch is not really the way to go. The engine size you mention sounds reasonable too, eg 3 inch and five inch bores by 4 inch stroke. Note that the stroke does not make a lot of differenc...

The expanders I used came from : http://www.powermaster.in/ They were no problem to deal with and sent things promptly. They don't do credit cards so you have you jack up a bank transfer. The drain valves you mention are exactly the sort of thing I have put on mine. mine have an o ring for the seal ...

There might be an optimum size for propellors, but I suspect that it is bigger than anything we can normally fit in. So for practical purposes, use the biggest diameter you can reasonably fit in. If that is quite big, then use narrow blades rather than the wide ones seen on infernal combustion engin...

Well, I thought I had seen figures for power plants that were higher than 50%, maybe they were for combined cycle plants, which these days reach 60%. Note that this is the overall efficiency from thermal to electrical, so includes any loss in the electrical side of the plant...for boats and vehicles...

Hi Mal, Gearing could be applied either way...if you had a long stroke low speed engine and a hull with a small clearance for the prop. you could gear the speed up to allow a smaller propellor. Apart from the loss in the gears themselves, the smaller propellor would be less efficient. Or if the engi...

There is no particular reason why a steam engine of the same general proportions as the chainsaw should not turn at the same RPM, which is where inertial loads start to be a problem. If they weren't, the chainsaw itself could probably go even faster. The main reason we don't normally try to build en...

Actually the very largest steam plants can reach efficiencies well over 50%, and the most efficient plants are combined cycle plants that include a steam cycle as part of the combination. But this is not very relevant to our small steam plants. One of the local boats, a bit over twenty feet long, wa...

I think there is some kind of law against treating small steam engines so cruelly :) The maximum power for a steam engine is determined by how much load the bearings can stand and how fast you are prepared to let it rev. Higher pressure will give you more power at any given speed, letting it rev wil...