There is as a system of canals that connects a country, these canals are about 10 meters wide 15 meters deep. I am designing a ship that was built specifically to travel the canals. Its main purpose is maximum weight while maintaining a speed of 8 miles per hour or about 7 knots. The ship size should be enough for heavy transport so no small boats.
The question is what are some ways that I can achieve a 7 knots speed?
Some points to consider:
- The material that the ship is made of is wood and whatever metals used in building a ship, keep in mind that I can invent wood with some different properties if that would help.
- The ship transports people or animals or sometimes just cargo.
- Winds can't be considered because these ships need to move when needed and people can't just wait for the winds.
- There isn't a significant current or stream to use for the ship movement.
- There is a series of outposts all along the canals something like every 5 miles. I made these to serve as posts where profesional rowers await in case an urgent message needs to be delivered so that they can keep a fresh crew. These outposts can be developed further if needed to accommodate the cargo ships.
- There are animals that naturally dig canals that were domesticated and then used to dig the canals.
I know an obvious answer would be an engine of some sort but that would result in my world industrialization (I need it to remain medieval-like.) Rowing teams are also not ideal. An idea that I had was to use animals on both banks of the canal to pull the ship and replenish them at the outposts. That would work but I am looking for more of a mechanical solution.
I thought of using a rope that can be in reeled at each outpost but I can't just have a five-mile rope. I thought about using some form of stored power (other than a steam engine) - something like compressed gas that can be used to move the ship - but I doubt there was technology in medieval time that could compress large amounts of gas.
A steam engine would work but I would need a reason that those people don't just look at it and think of using it to build trains and cars (ruining the time period I'm looking for.)