Steam boat engine

It would likely be a side paddle steamer powered by some form of piston expansion engine, operating in a similar fashion to that of a steam locomotive. Operationally, these things are controlled by steam valves, and they generally have the capability to operate in reverse.

You might search Youtube for some videos on paddle steamer operation to give you a better idea.

This was just a few years before your period and was 'start of the art' https://en.wikipedia.org/wiki/SS_Great_Britain

Side paddle steamers and rear paddle steamers were both very popular for river use. They combine power with a very shallow draft. You don't have to get the power down as deep as a propeller.

Reverse gear is very useful and can be done with a fairly primitive transmission. Many steamers landed on shore and would need to back up to get going again. Also if you go aground on a sandbar, reverse might be the best way off of it. Same mechanical principal as a train engine. It would have been one of the first developments to be implemented.

Speed would be controlled by a value that increases or decreases the steam pressure against the gear providing power. Decreased pressure would cause it to slow down and increasing the pressure would cause it to speed up. (Realize that "speed" here is a relative term. These suckers didn't go very fast.)

Control would be at the bridge. However, where it actually happens would be down in the engine room. You could use either a mechanical telegraph or voice tubes. The bridge would be where steering commands were also issued.

I'm not sure you need much more than the captain issuing an order down the voice tube to the engine room. Take a look at https://en.wikipedia.org/wiki/Steamboat. It includes a picture of a model of a very primitive steamboat.

Jim Clark-Dawe

efreysson said:

I appreciate the input, but to repeat I'm thinking of a small craft; the kind a regular person could rent. And for plot purposes it only needs to hold fifteen people.

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If it's a rental, I'd be surprised if the company doesn't make you hire an engineer to run the engine. Even at the low pressures the early steam engines obtained, it would be easy to overpressure something, and you do have a boiler to worry about.

I'm picking up on the "on a canal". Most canals in the UK are narrow - and the main vessel was the narrow boat.
However there are navigable rivers - nothing like the Missisipi - and I have seen steam pinnaces on the Thames. They come in a range of sizes and also used to be used by the navy for running errands around a fleet - and they were also the transport of Admirals. See:

Also remember that in running any steam engine, someone has to shovel coal into it on a regular basis and also know when to top up the water. It's not as easy as a press a button to start motor with a tank of liquid fuel.
https://www.nmrn-portsmouth.org.uk/exhibits-and-collections/steam-pinnace - for a naval one
There are similar boats also referred to as steam launch and in searching for a steam pinnace on the Thames came up with a company that hires them out.
https://www.frenchbrothers.co.uk/private-hire/bespoke-events/steamboats

and a link to a small one
http://www.hscboats.co.uk/boats/swan-of-teynham-a-steam-launch/
(Too small for your party I think.)
A paddle ship like the ones in films on the Missisippi would be far too large for the Thames - the road bridges are too low to let it through and also the width of the river would count against it. Note that if you are modelling closely on London, that road bridges tend to be Victorian and earlier both over rivers and canals - and often relatively low. There are occasional swing bridges - but these are usually on tidal parts of rivers where you once had sailing ships wanting to come in to docks.
Also, if you are navigating on a canal, every so often there are locks and someone has to operate the gate and the pumps.

efreysson said:

I appreciate the input, but to repeat I'm thinking of a small craft; the kind a regular person could rent. And for plot purposes it only needs to hold fifteen people.

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Maybe searching for 'steam launch' would help? Googling 'steam lauch' and going for 'images' gets this:
https://www.google.ca/search?q=stea...eN-KbaAhVSWq0KHT5GBhcQsAQIJg&biw=1093&bih=500

A variety of small to mid-sized boats, many suitable for an afternoon on a lake or river.
And, unless one of the guests is very familiar with steam boat engines, I'd go with the rental company providing an engineer/supervisor. There are rules-of-the-road even on fresh water. One does not just go 'whoosh' on down the river. Especially in someone else's expensive boat. These boats were neither stamped out of aluminum, nor built up out of fiberglass. Read some descriptions in the sales listings - fine woodwork, brass fittings - you wouldn't want some idiot mishandling the boiler and blowing the whole thing up. Or hitting a rock that magically leapt in front of the boat. Etc.

Take a look at https://en.wikipedia.org/wiki/Pyroscaphe

Understand that the principals of control are the same whether it's a big ship or a small boat. Smaller means less complexity and number of people. It's just easier to see the separate functions in larger boats because of the separation. Remember that the size of a boat is related to the size of the waterway and the skill of the builders. But the basic principals involved in something like the Pyroscaphe is the same as a big Mississippi steamboat.

Running a steam engine is a complex operation. Too hot or too cold and you've got problems. Too much pressure and it explodes. Too little pressure and it doesn't go. Especially the early ones required a lot of skill and things still went wrong. I also doubt you could rent the boat without a crew.

Jim Clark-Dawe

Check out the steam boats in Maverick, the movie. There are several shots of small steam boats as well as the larger Lauren Belle, which is actually a steam tug boat borrowed from a Museum for the movie.

DrDoc

Watch The African Queen. It's a good movie.

Jeff