[notahacker]

Roman "steam power" worked nothing like a condensing engine and was nowhere near adequate to power a ship.

Ironically, rowing vessels was one of the tasks Romans preferred to use freemen where possible. And even the best galleys with the most motivated, coordinated and healthy rowers were vastly inferior in speed and endurance to steamships (or indeed sail powered tea-clippers). But you needed a lot of intermediate inventions to get from a lightweight device that rotated by blowing out hot air to a steamship that could cross oceans. Or from a trireme to a tea clipper that would travel faster relying on just the wind, for that matter

[ghaff]

I wonder what the Romans could have done with designs for "modern" sailing ships? Though I also wonder how relatively useful they would be as warships absent cannons.

[mcguire]

Here's a question back at you: how well do modern sailing ships handle the Mediterranean in winter?

As far as I know, the winds haven't significantly changed: mostly from the northwest for most of the year, with a period in the spring and summer where they swing to the from the northeast. Also, ferocious storms in the winter.

Going clockwise along the Med's coast from France to Italy, Greece, the Levant, and to Egypt is "downhill"; going the other direction will take roughly twice as long. Sailing along the north coast of Africa is kind of dangerous because a storm or navigation mistake plus the prevailing winds can put you aground hard and unexpectedly.

Modern sailing ships are much better at sailing closer to the wind, are much less limited by supplies (it's hard to get more than a few days endurance from a rowed galley) and are more seaworthy, because they could extend the sailing season and take more direct routes.

How much better is that? I don't know, but I suspect a fair bit. Galleys still have advantages in some circumstances.

Now, if you throw in some even remotely modern navigation equipment, that would be stupidly advantageous.

Source: John Pryor, Geography, Technology, and War.

[MichaelCollins]

> Though I also wonder how relatively useful they would be as warships absent cannons.

Without cannons, maneuvering becomes a lot more important because you rely on either ramming the enemy, or pulling up alongside them and boarding them (or both.) These tactics favor rowed galleys, which can sprint quick for short distances and don't depend on the wind.

Even after the invention and proliferation of cannon, navies and pirates in the Med continued to use rowed galleys, direct descendants of ancient triremes, through the middle ages into the 18th century.

[notahacker]

if the Romans were the only empire with relatively modern sailing vessels, I'm not sure lack of cannon would have hampered them.

And the inhabitants of most of the areas they'd be able to reach beyond the Mediterranean and Red Sea weren't going to sail out to meet them.

I guess a Roman conquest of the Americas would be pretty boring for archaeologists and architecture students. No Macchu Picchu or Teotihuacan, not even a Chan Chan, but the crumbling 2000 year old columns of Washington DC instead ;)

[ghaff]

Of course, if you already have the technology to build boats, it's not going to take you long to copy the other guy's design.

Later sail warships mostly didn't use triangular sails either. I assume this is related to volume in some manner. Clipper ships were very fast but they had relatively little capacity so were used for high value goods.

[bsder]

> Later sail warships mostly didn't use triangular sails either.

Presumably the whole "fabric is ferociously expensive" problem.