Roman trade ships -- how did they control the rudder?

[agamemnus]

I am trying to make a realistic Roman trade ship model.

 

Does anyone know how Roman trade ships -- especially large ones (ie, around 50 meters in length) -- controlled the rudder? I have been trying to figure this out for a while now.

 

I know that they used massive oars on the side of each ship, and that a helmsman situated on the roof of a small tent structure controlled the oars.

 

From all the pictures and descriptions I have seen, though, the helmsman is seen controlling a wooden plank attached to an oar, and the oar is held in place by a series of ropes (tackling). The problem is that the helmsman could not possibly maneuver the oar more than a handful of degrees, because he'd otherwise need to have huge arms in order to move the planks. The planks would need move circular fashion, at an angle to the ship, since the oars are also at an angle.

 

My conclusion is that some sort of rope system was used that controlled the attached planks, but I have no idea how it would work.

Edited January 7, 2011 by agamemnus

[caldrail]

Unfortunately I'm a complete dunce about things nautical, but according to the somewhat limited information I have about sailing and in particular to the use of oars used as rudders, the downside to this approach is indeed control at higher speeds. bear in mind that Roman ships would not cruise at the higher speeds possible unless the wind allowed it. Unlike an engine driven ship, the capacity for oarsmen to keep a vessel at a good pace was quite limited.

 

It's a fairly safe bet that maximum speed was for straight lines only, though I'm quite happy to be put straight on this. As for manoeverability, although the initial push of the oar against the water flow might require some strenuous effort, bear in mind that the whole point of the exercise is to turn, thus the vessel 'equalises' as much as possible, a compromise between the physical forces between the interia of the hull and the pressure on the oar reduces the overall need for muscle, if not entirely. The leverage of the oar at the rear of the ship accentuates its effect.

 

Now as for the rope system you allude to, that's speculation, because nowhere have I ever read of such a system used on Roman ships.

 

I now sit back and wait for my opinions to be swept aside by the tide of expertise on this subject.

[agamemnus]

If there is no rope system.... for large ships they would need two helmsmen (one for each side), then, I guess?

 

I say this because the width of the ship would be too great for one helmsman to handle... the oar handles would have a very big length and circumference, and you would otherwise need a rope system or very big arms.

[Klingan]

If there is no rope system.... for large ships they would need two helmsmen (one for each side), then, I guess?I say this because the width of the ship would be too great for one helmsman to handle... the oar handles would have a very big length and circumference, and you would otherwise need a rope system or very big arms.

 

I will have to place myself, as Caldrail did, in the corner of ignorance of the subject but I have some images you might be interested in:

 

Mosaic from the market at Ostia.

 

Mosaic from the market at Ostia.

 

A clay ship model from Sparta.

 

The graffito from Casa della Nave Europa in Pompeii.

[Maty]

For what it's worth, here's a description of one of the naves onerariae written in AD 200. This is the Isis, blown into the Pireaus by a storm.

 

"What a size that ship was! 180 feet long, the man said, and something over a quarter of that in width; and from deck to keel, the maximum depth, through the hold, 44 feet. And then the height of the mast, with its huge yard; and what a forestay it takes to hold it! And the lofty stern with its gradual curve, and its gilded beak, balanced at the other end by the long rising sweep of the prow, and the figures of her name-goddess, Isis, on either side.

 

As to the other ornamental details, the paintings and the scarlet topsail, I was more struck by the anchors, and the capstans and windlasses, and the stern cabins. The crew was like a small army. And they were saying she carried as much corn as would feed every soul in Attica for a year.

 

And all depends for its safety on one little old lump of a man, who controls that great rudder with a mere broomstick of a tiller! He was pointed out to me; Heron was his name, I think; a woolly-headed fellow, half-bald."

Samippus in Lucian's the Ship 5

 

Some caution is required because Lucian might have come over all literary instead of reporting fact, and secondly, the translation I have given is an unreliable one - you'll need someone better than I to look at the original. But it might repay investigation.

[Klingan]

Here's a link to the passage (passage 435-437, p. 172-172 in this edition).

[Melvadius]

I agree that the whole passage may well be worth reading if you are considering making a model although I do wonder at the reference to counting the hides to see how big the sails were. That would seem to indicate that they were using leather sails which I would have thought would have made working them extremely difficult due to the weight involved. Possibly this was just being used as a convenient indication of size as I understand that the Egyptians used linen (a possible alterantive sail material) weaving frames of a specific width while goat/ sheep hides used in leather tents found to date although a natural material also seem to have a standard size. I suppose one could be used as a convenient extrapolation factor for the other.

[agamemnus]

http://img833.imageshack.us/i/70918991.png/

 

http://img600.imageshack.us/i/12307216.png/

 

Only thing I could think of for the mechanism so far. (no ropes/tackling from the sails to the rudders/oars added yet)

Edited February 1, 2011 by agamemnus

[agamemnus]

Two new screenshots after I did some more work.

 

 

[Melvadius]

I'm not sure that your first option would work as the internal support could severely restrict the turning of the rudder when the ship was in danger of running ashore. Don't forget that in this period at, least with smaller vessels, you have to be able to unship the rudder at times when working close to a shelving beach especially if you may intended to ground the vessel for loading and unloading.

 

Given that you are dealing with a very large vessel is it not possible that the Roman made use of the rear platform to centrally mount a single rudder sweep fixed by a 'universal joint' made out of over-crossed hawsers/ large ropes?

 

Alternatively doing a general web search I stumbled across this image apparently of a later Byzantine Droman which seems to show a different rudder arrangement. The original source of the image is apparently from The Climax of Rome by Michael Grant

The plate is from The Mansell Collection.

 

A possible better source is this site which is the R

[agamemnus]

I'm not sure that your first option would work as the internal support could severely restrict the turning of the rudder when the ship was in danger of running ashore. Don't forget that in this period at, least with smaller vessels, you have to be able to unship the rudder at times when working close to a shelving beach especially if you may intended to ground the vessel for loading and unloading.

Yes, that's a problem. After reading Mott's 1991 paper more thoroughly, I also realized that the rudder needs to move along its support (which I haven't added yet) depending on the weight of the ship: a low weight means that the ship is high above the water and there is no pressure on the rudder. A large weight (when the ship is full of stuff) means the ship is riding low on the water and there is a lot of pressure on the rudder to move up.

 

I thought of a solution to this -- make the top part of the rudder into two planks, and place the jutting out plank in the center to allow it to slide up and down.

 

Another problem that I saw after I thought about this is that the rotation of the rudder would cause the iron pipe to move slightly up or down, and that would break the current casing.

 

Given that you are dealing with a very large vessel is it not possible that the Roman made use of the rear platform to centrally mount a single rudder sweep fixed by a 'universal joint' made out of over-crossed hawsers/ large ropes?

I didn't realize that universal joints were a possibility. Apparently, from the Wikipedia article on them, they were known since Greek times! This may solve the problem of the rod/paddle/oar/rudder not staying at one height.

 

I'm not sure how you'd design a central rudder sweep, though... care to make a crude drawing? (maybe I could just join the two parts I have into one part? For such a long piece, it might have to be either made of crude steel or a thick piece of wood to hold together, though. Probably crude steel.

 

Alternatively doing a general web search I stumbled across this image apparently of a later Byzantine Droman which seems to show a different rudder arrangement. The original source of the image is apparently from The Climax of Rome by Michael Grant

The plate is from The Mansell Collection.

 

A possible better source is this site which is the R

Edited February 2, 2011 by agamemnus

[Medusa]

The following websites might be helpful in finding images of Roman ships:

 

http://www2.rgzm.de/Navis/Home/NoFrames.htm

http://www2.rgzm.de/navis2/home/FramesE.cfm

[agamemnus]

Indeed interesting.

 

I am starting to wonder how big the real average size of these things were.

 

Tiny:

http://www2.rgzm.de/Navis/Ships/Ship050/Image/050F0026.jpg

 

Well, at least they had fish wells!:

Fiumicino 5 is characterised by a well positioned in the middle body of the boat. This is an aquarium-container which was used to keep fish fresh until the sale of the catch.

The fishing well, troncopyramidal in shape with a squared base (1 m x 1m), is a box made of very thick planks (5 cm) assembled with mortise-and-tenon joints. The corners are stiffened with iron nails. The bottom transversal elements are shaped with the curvature of the hull and are fastened to the planking by copper nails driven in from the outside. The upper elements have angular recesses for a wooden lid (not preserved). The bottom of the well has 19 holes (diameter 2,5/3 cm), some with wooden plugs, to fill it with fresh sea water.

 

 

Edit: holy frack!

 

http://www.culture.gouv.fr/culture/archeosm/archeosom/imatges/archeosm/mule.jpg

 

THE FOURMIGUE C SHIPWRECK

Salomon Reinach said that "the sea is the most immense museum in the world." Actually, beginning in the nineteenth century, the bottoms of the sea, of rivers and lakes, have surrendered numerous masterpieces of ancient sculpture, such as the Ephebe of Agde, to fishermen and divers.

 

At the beginning of the first century BC, a Roman ship capsized near the Gulf of Juan, not far from the turret of La Fourmigue. It transported a magnificent cargo of pieces of furniture.

 

Several of the pieces that were raised belong to bronze beds that were decorated with finely carved sculptures.

Edited February 3, 2011 by agamemnus

[Klingan]

Edit: holy frack!

 

http://www.culture.gouv.fr/culture/archeosm/archeosom/imatges/archeosm/mule.jpg

 

THE FOURMIGUE C SHIPWRECK

Salomon Reinach said that "the sea is the most immense museum in the world." Actually, beginning in the nineteenth century, the bottoms of the sea, of rivers and lakes, have surrendered numerous masterpieces of ancient sculpture, such as the Ephebe of Agde, to fishermen and divers.

 

At the beginning of the first century BC, a Roman ship capsized near the Gulf of Juan, not far from the turret of La Fourmigue. It transported a magnificent cargo of pieces of furniture.

 

Several of the pieces that were raised belong to bronze beds that were decorated with finely carved sculptures.

 

Damn, I wonder where that piece is now!

[agamemnus]

I just figured out a very simple and elegant solution. I can simply add four or five "gear-like" wedges to the top of the oar/rudder. Pair that with a ring formed in the shape of a circle with some matching outside wedges and you have a way to rotate the oar/rudder at both a variable weight and rudder angle. Model pics will come later-ish!

 

Edit: Here are the pics at the bottom. Not really sure what's to hold the bottom part of the whole contraption (the gear) to prevent it from snapping under the weight. Perhaps some manually adjusted rigging lines attached to the mast, somehow.

 

 

 

Connecting the right and left controls would help disperse some of the weight. If it was a large wooden rod, it might snap, so I think it'd be iron. I really don't know whether any such iron rods were found in any shipwrecks, though. Still, I'm not sure what the largest recovered ship was... as far as I can tell the ships in the shipwrecks weren't really too big. (excluding the Nemi ships)

Edited February 11, 2011 by agamemnus