News to both navies at Lepanto. While classical Greek and Roman galleys were crewed by free men, in the Renaissance Mediterranean convicts and slaves formed the bulk of the crews of war galleys. The goal is to sink the enemies ship with all aboard, not board her and hope for the best. If you foul your oars AND the enemy boards you rather than sinking your helpless vessel AND the enemy wins, why would they free valuable loot/the propulsion system for their new warship? Chained to the ship one’s options are limited.
But we are talking about pre-motor-powered boats, right? By that logic, there is a reason propellers were not used before motor powered boats; oars were more efficient for the state of technology at the time.
In addition to the issue that oars spend a bit less than half their cycle providing no propulsion, there is also the matter of air resistance. Feathering an oar to reduce drag on the out-of-water portion of the stroke is still merely a reduction, not an elimination, of that drag. (I suppose you could try to always run downwind so that you get a tiny sail effect off the returning oars, but, in general, it remains an expenditure of manpower to perform an action that does not propel the ship while continuing to actually impede forward motion (to whatever tiny degree).)
I remember reading about that pull-off in the Children’s Encyclopaedia, of all places, and that’s exactly how the screw-vs-paddles question was settled, and why I was all set to chime in on the superiority of the screw.
I’m not sure it would have to be all that sophisticated in terms of design, but it would need to be of fairly sophisticated manufacturing. Would ancient greek technology be up to making the gears, belts/chains, propshafts and so on?
What technology does the OP assume is available for transmission & propeller design & construction?
Today we can build a 170-man pedal & transmission system with (WAG) 10% loss = 90% efficiency or better. Using the technology of ancient Greece we might have 90% losses & 10% efficiency, if it could be built at all.
Propellor design has come a very long way as well. The early props of the 1800s were pitifully inefficient compared to modern designs, even if we stick to props of the same general size. I’d say the difference with new vs old is 2 or 3x more useful thrust per input power.
These two differences will more than overcome any of the points made above about oar-out-of-water-time, air drag, or the difference between generic drag-based or lift-based propulsion.
They were sophisticated enough to make this.
In fact, the Lepanto era rowers were chained to the oars – for months at a time. You could smell such ships from miles away. Incidentally, the Maritime Museum in Barcelona has a full size replica of John of Austria’s flagship from Lepanto. The officers quarters is fantastically appointed, but I couldn’t help thinking that all that luxury would do nothing to mask the unbearable stench.
It occurs to me that oars have one big advantage, especially for slave-rowed ships. It’s much easier to tell whether a rower is slacking off: if he’s not keeping pace with the others or his oar isn’t staying in the water as much as the others, time for the whip!
Reading this, I wonder if oars give an maneuverabilty advantage over a propeller boat. It seem that it might, but I guess it would depend on the way naval battles were fought back then.
I would guess that the advantage of using oars could be negated by having two propellers.
That said, I’m with LSLGuy on the difficulty of making this with ancient technology.
Yes, but I’d be interested to know how strong a gearbox etc. they could make given the materials they had available. And how much it would have cost them.
The whole technology is speculative. If we consider that they have the knowledge of propellors, don’t they also have knowledge of gearing and basic power transmission? That stuff came first anyhow, in water mills.
No gearbox needed.
You could do this several different ways. First off would be to make a crankshaft similar to what the CSS Hunley used Only with two crank throws per person. The people supplying the power would sit with their feet on the “pedals” (crank throws) and have at it.
It you will allow a bicycle chain technology then it gets real easy. Look at this picture of a tandem bicycle. Replace the real wheel with a gear on the propeller shaft. You people sit facing away from the centerline of the craft and pedal for all they are worth.
I’d think cast bronze & wrought iron etc would be plenty strong enough. Remember, these were people who made a stone , iron & bronze statue that straddled the entrance to a harbour. I don’t think cost would necessarily be an obstacle. But my link to the Mechanism was more about their sophistication when it came to gearing and the like, not the strengt6h of their materials. You did specifically say sophisticated manufacturing.
Yes. Manufacturing, the process of making a finished product from raw materials, such as taking a heap of assorted minerals and turning it into a functional gearbox, crankshaft or whatever, of which the most difficult bit is often making the material. I could probably make an adequate gearwheel from a disc of steel, using nothing but abrasives and a LOT of time, but making the steel would not be easy. Even more so for most castings.
However given that there are watches made entirely from wood or bone, and windmills etc. with wooden gears this may be moot. For all I know you could carve perfectly adequate gears out of wood or something, providing you kept the ratios relatively sensible - it would depend on the amount of power and RPM the system has to deal with, I suppose. How many horsepower is 170 humanpower?
From Hyno-Toad’s input, slower props are more efficient, so maybe two big, low-speed props transmitting 85 humanpower each at low RPM would be the way to go, providing you don’t lose to much power due to friction etc.
Use the bicyle approach to transmit power to a shaft using leather belts or similar, to make life easier. How much would the prop rotation speed need to change as the ship went from stationary to top speed? Could the pedallers cope if you just fixed the shaft directly to the prop, maybe with a slip clutch to ease starting, or would you need some way of changing the gearing to keep prop and pedallers in their optimum speed ranges?
Even if you did need a gearbox, maybe you could make the wheels very wide and/or use curved (helical?) gears to reduce the strain if something like bronze or iron wasn’t strong enough. Heck, if we’re assuming a detailed Greek knowledge of propeller technology, we may as well throw a blast furnace into the mix and make some alloy steel if necessary.
Hmmmm <strokes chin> this might actually work - prepare to face my Imperial Pedalo of Death[1], puny rowers!
[1] And very slow turning around
Is the boat on a treadmill?
Hmm, in that race, the Olympic athletes were kayakers, not rowers and those two guys only kept up with the fastest of the single kayakers. A racing scull is gonna go a heck of a lot faster than a kayak.
In rowing, you get most of your speed from your legs as you push off fixed shoes and force the blade through the water. The back and arms finish off the stroke but don’t offer nearly the power. The biggest problem I see with rowers versus peddling is getting 170 rowers to row together to get the most efficient stroke. It’s hard enough getting 8 guys to row together. If the rowers are inexperienced, they’ll rush up the slide and “check” the boat by slamming their weight into the stern. (I.m assuming if you’re gonna have some fancy, gear driven propeller set-up, you’ll have a nice rowing set up instead of just benches and oiled breeches). That difficulty alone would tend to favor peddling where it’s much easier to get a bunch of guys peddling together.
What would be interesting would be a pedal driven propeller boat up against a truly well-trained eight.
The Colossus of Rhodes was an impressive achievement, but it did not straddle the harbor. Read the article you linked.
Go to your room.
It was a colossal error. I wonder at it.