If someone in the 14-15th century world had the knowledge required to build an engine for use in locomotives and ships, what kind of engine could be made using technology that already existed back then?

  • $\begingroup$ I edited your question to make it more direct and added some tags. I will say that, while adding an engine to a ship could be a great invention in the right circumstances, building a locomotive makes no sense in a world without train tracks. Maybe you meant something more general instead of "a powered rail vehicle used for pulling trains"? A land vehicle? An electric carriage? $\endgroup$ Feb 2, 2019 at 20:50

2 Answers 2


Steam engines

Edward Somerset had a patent for one in the 1600's and Thomas Savery (1650–1715) was the inventor of the first commercially used one, which is only 100–200 years past your time frame.

But the first recorded steam engine was as early as the 1st century Egypt so the principles were known 1500–1600 years before your time-frame which means it's far from a great stretch for you to say development of steam engines that entered common usage was a little earlier in your world.

The propeller didn't come along for a while longer than that of course but paddle steamers are simply a reverse water wheel (which the Romans had) and Archimedes' screw also existed then, so that gives you two potential methods of transferring power from the engine to propel your ships.

Paddle steamers are your most likely ships, especially as the Romans already had ox powered paddle boats (there's a reference to them in the link).

A simple vertical single cylinder engine used to drive a wheel or paddle is probably most likely.

Though this horizontal design is a touch more elegant to my eye.

inserted elegant design!

They'd probably be wood burning rather than coal.

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    $\begingroup$ Referencing the aelopile is misleading. Until you can develop much better materials, it's a dead end. And the working principles used are not easily applied to other approaches. $\endgroup$ Feb 2, 2019 at 19:42
  • $\begingroup$ +1, but note that "the 14-15th century world" means the period from 1301 to 1500 (and presumably closer to the center of that range than the edges). So some of your figures (describing 1698 as "only 100–200 years past your time frame" and the first century CE as "1500–1600 years before your time-frame") seem a bit off. $\endgroup$
    – ruakh
    Feb 2, 2019 at 21:11
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    $\begingroup$ Note that Somerset's/Savery's engine isn't a steam engine as we think of it. It's a steam pump, using steam acting directly on water to move the water. If you replace the water with a piston, you now need much higher manufacturing tolerances to keep the steam from blowing past the piston. Further, early 1700s' metallurgy was just barely capable of making parts that wouldn't blow up under pressure; I doubt that 1400s metallurgy could do the job. $\endgroup$
    – Mark
    Feb 2, 2019 at 21:24
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    $\begingroup$ @Mark a pump capable of moving water is enough for ships. In fact I am actively annoyed about how alternate history fiction insists on building complex steam engines and paddle wheels or propellers when the first step for a ship probably should be a pump working directly on the water. Historically this did not happen because our steam ships are just ships with steam engines developed for another purpose but if you write a story about using "future technology" to build superior warships in a few years... And yet everybody does what our history did but faster. $\endgroup$ Feb 3, 2019 at 0:10
  • $\begingroup$ @Mark And no, this does not really have anything to do with you or the topic. It just happens to be a pet peeve of mine so I could not resist the temptation. Sorry. $\endgroup$ Feb 3, 2019 at 0:11

in the 1300s the only sources of power that could be mobile were people and animals. Using animals on ships was almost never done because it was wildly impractical to have treadmills taking up needed cargo space and food to keep them well enough fed to be able to work.

The metallurgy needed for harnessing steam was not available in this time period, now were the machining tools needed. Lathes were not invented until the late 1700s and even an expert blacksmith would not be able to make a piston using hand tools

Steam engines can be made of brass or bronze, both horribly expensive in the 13-1400s, but only in small scale, like in model engines. These materials cannot handle the sort of pressure needed to drive pistons well enough to overcome the friction of a propeller in water, and they cannot be made powerful enough for a land vehicle able to transport any great weight. Turbines .. well no .. just no.

The Conneticut Yankee in King Arthurs court took years to build the infrastructure that allowed him to build 19th century weapons and electrical equipment .. but building the entire tool chain took him decades.

so if someone with all of the needed branches of knowledge, and a wide ranging practical experience of manufacturing, does wind up in the 1350 wanting to build a ship bigger than the Santa Maria (19 m x 9 m ) he would have to be an expert negotiator and manipulator to make it happen.


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