I wanted to clarify that my steam boat is not an advanced steamer, just the piston engine mounted to water wheels. The boat is also not very large, requiring less strain on the engine.
In my TL its been nearly 20 year since Heron started working on more advanced engines. Six of those years Heron himself worked on the project and he would qualify as super-genius. Palonius is intelligent but no where near Heron’s level. However, he has hired Braxis who worked with Heron on his projects so there is a continuation. 20 years of work to attach a basic steam engine, even if it is weak, to a boat does not seem that far fetched. Especially when you are surrounded by the most brilliant people in the known world to goto for advice if needed. True, none of them would be able to advise about a completed steam engine, but things like temperature, metallurgy, mechanics, etc. would be reasonable.
I also suggest the engine they are using now can be built without measuring pressure and temperature precisely because the tolerances at this level are more forgiving and, having worked with steam engines for years, they would have a good idea about how hot to make the boiler.
Ofcourse, if other people want to use these engines or, if more pressure is required, being able to measure pressure and temperature more accurately becomes important but we must consider the cause and effect of technological development. Tools for measuring temperature and pressure could be created because they are needed for better steam engines.
A little concerned about posting more, but, here it goes
77AD- Two years pass as Palonius launches the second and then the third iteration of his self-powered vessel in front of an ever-shrinking base of onlookers. Unlike The Heron, The Heron II did not explode and sink, allowing to be used for the much-improved The Heron III. Although from a Patrician background, Palonius fortunes had declined significantly since leaving Rome and embarking on his new career path. The Library provided a small stipend to continue Heron’s work as well as access to all of its facilities, but much of the cost for materials, including the purchase of ships and expensive fuel, the hiring of workers, and healthy amounts of iron and bronze, came out of his own pocket, pockets that had begun to grow lighter in the past few years.
After making it back to shore and failing to salvage the mass of splinters that was The Heron, Palonius was approached by one of those who had been watching the disaster. Phillip, a Greek civil engineer, observed that his drive wheels looked like a series of traditional ores arrayed in a circle for contentious operation. Water wheels, he explained, such as those used for mills around the Empire, caught water in their fins and rotated. He suggested the opposite might work as well, with the fins in the water wheel pushing water out to propel the craft.
After modifying the common water wheel design to make it more suitable for his purposes, Palonius found it much more effeciant, with less wasted energy an less agitation in the water. Acceleration was very poor as was the vessel’s top speed but, it was constant and sustained.
The location of the boiler was lowered to reduce the vessel’s center of gravity and multiple containers were used to house the needed water rather than one large one in order to reduce the sloshing effect. Unfortunately this made the entire apparatus heavier and more expensive but Palonius was primarily concerned with making it work rather than making it practical.
After these, and other, more minor, corrections were made, Palonius and Braxis completed their first successful navigation of Alexandria’s harbor. For the next few days they put The Heron III through various trials, testing its speed, maneuverability and durability in different situations. More adjustments followed but at last, satisfied the craft would survive an extended journey, they set sail for Tyrus in Syria to begin their promotional mission.
After a few hours of steaming along the coastline, Palonius and Braxis discovered the oven that contained the boiler was beginning to crack, or more specifically the clay coating. Power to the pistons, also, was beginning to lag. Within 15 minutes the cracks had widened and begun to show signs of moisture. Since fluids were supposed to be contained within the boiler, this drew concern. Opening the door into which fuel was cast yielded little information as the heat and flames obscured their vision. Not wishing to lose The Heron III, Palonius gave the order to pull ashore.
The fires around the boiler were allowed to cool for several hours before Braxis squeezed inside to inspect the elements. He found the pipes bringing water into and steam out of the cauldron had deformed and cracked. The cauldron too, showed signs of stress and was seeping water around the lid. As water leaked into the furnace it built pressure inside, causing it to expand and thus cracking the clay.
Palonius decided it was too dangerous to run the boiler for so long a time and instead ordered the ship sail for Caesarea Maritima on the Judean coast for repairs. He wanted to steam into Tyrus instead of sail. After reaching the much smaller port city, he rented a mooring and began the tedious task of disassembling the boiler.