I know I posted that in the comments box but it disappeared from view fairly fast...

Why is it that the norse longships (drakkars) are estimated to have been ocean-worthy but not triremes/quinquiremes?

AFAICT, they are both rather small, rather sleek hulls, combining sails and oars. Wiki tells me triremes achieved a respectable 6-8 knots without forcing too much. Drakkars were deemed to achieve 5-10 knots. Both could reach 14-15 at maximum speed.

So what's the difference?

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The primary difference is the shape of the hulls and the flexibility.
The long ships, being clinker built where the planks overlap, are very flexible where as the classic Mediterranean galley is built up of edge pinned planks which are not as flexible. Also the long ships had fairly low freeboard for their lengths unlike the more lofty trireme.
If you look at a cross section of a long ship compared to a trireme or any galley, even a sleek 18th century one, you will see that the hull is relatively lighter than the longship and much more prone to hogging. The Greeks and Romans needed to use long cables tensioned fore and aft to keep their galleys from sagging. The largest long ships may have done the same, we don't know for sure about that.
So what made the longship more "sea worthy"? In rough seas a ship has to be able to either resist bending in all directions OR it must be flexible enough to survive bending without failing. In the case of the longship, with its very flexible hull, it rode over the waves more nimbly. Sailors who have sailed reproductions have often been alarmed at the movements of the hulls in a sea way.
This flexibility was a severe liability if the vessel was used to ram anything however, which is why the galley is so stiff fore and aft. For the same length of hull a longship could survive sea conditions that would overwhelm and smash a galley.
Interestingly enough the trading ship versions of the longship, the Knarr, and Mediterranean vessels could safely navigate severe weather conditions so it isn't simply the construction technique.
F

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Thanks for indulging me, it's very useful info.

A couple of follow up questions, if you don't mind?

Is it possible to build galleys with the clunker method? The wiki for galleys seems to suggest it was actually done (then again, they tend to include longships under 'galleys', which is pushing the definition, I think).

And would that radically alter the dynamic of the ship on the oceans?

Would a low freeboard not be a disadvantage in the case of rough seas? I am asking because Wiki (again) cites the higher freeboard of the carrack as an advantage for ocean-going...

I understand the issue with hogging/sagging and the dilemna with rigid vs. flexibility. Could the fact that the galley had a tendency to hogg be compensated with a more rigid hull? Or one with some ballast?

Btw, I am asking all that because I am trying to establish how the Greek/Roman Empires (if they had not collapsed) could have sent ships across the oceans give or take a few more centuries of development...

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If they had done so, they would likely have made use of the Batavians, who dominated the channel and French coastline and gave Ceasar a headache fduring the conquest of Gaul. Although the fully developed longship is 1000 years later dated than than those, the Batavian ships were probably the same sort of clinker-built vessel. It is of course not known exactly how much sailing went on in the north sea area, although the book by Alistair Moffat points out that by about 500 the whole area around Britain was far more effectively traversed by sea than by land, and there were strong and active naval trade links.

Seeing as the Romans had no prejudices about using client peoples, and that the Batavians did become such a client, they could easily have utilised Batavian ships and crews.

Other than that, I don't think a few more centuries is enough. The galley is a radically bdifferent beast; the apparent similarities between the two are superficial. Also the Greeks and Romans lack access to high quality timber and pitch, which were a north european trading staple in later years. Galley development was steadily going toward bigger and bigger designs, rather than structural innovaiton, and the Romans were never very innovative anyway - their galleys were originally all copied from Carthaginian ships captured during the First Punic War.

Later mediterranean galleys are also different from classical galleys and the north sea ships, but their development also went to larger and larger designs and crews - which operationally actually reduced their effectiveness, because their ranges became shorter and shorter and they were increasingly reliant on purpose-built naval bases. A classical state could reasonably expect to project naval power from Greece to the Levant, but by the Renaisance in the conflict between Venice and the Ottomans they were much shorter ranged and had to be accompanied by a land conquest to seize coastal bases. Greece to Italy was about their limit.

Originally Posted by contracycle

If they had done so, they would likely have made use of the Batavians, who dominated the channel and French coastline and gave Ceasar a headache during the conquest of Gaul.

I know of that but I thought it was the 'Veniti' tribe (in Brittany/Normandy) which gave Ceasar a headache?

And while I can see in wiki a Batavian revolt with some Navy action, there are no description of Batavian ships. Would you mind having a look around and link something a bit descriptive?

Quote:

It is of course not known exactly how much sailing went on in the north sea area, although the book The Sea Kingdoms by Alistair Moffat points out that by about 500 the whole area around Britain was far more effectively traversed by sea than by land, and there were strong and active naval trade links.

The wiki article on galleys suggest that celtic/British isles navies of the time did use galleys too but, as I said, their definition of galleys seem pretty extensive.

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Other than that, I don't think a few more centuries is enough. The galley is a radically bdifferent beast; the apparent similarities between the two are superficial. Also the Greeks and Romans lack access to high quality timber and pitch, which were a north european trading staple in later years. Galley development was steadily going toward bigger and bigger designs, rather than structural innovaiton, and the Romans were never very innovative anyway - their galleys were originally all copied from Carthaginian ships captured during the First Punic War.

Okay, I'll send you what I am trying to do but it's RPG-related stuff so it's more like Greco-Roman-inspired (but with a medieval level of tech) rather than really Romans in the real world...

Their slave-based economy, as you pointed out, did not favour technological innovation...

Quote:

Later mediterranean galleys are also different from classical galleys and the north sea ships, but their development also went to larger and larger designs and crews - which operationally actually reduced their effectiveness, because their ranges became shorter and shorter and they were increasingly reliant on purpose-built naval bases. A classical state could reasonably expect to project naval power from Greece to the Levant, but by the Renaisance in the conflict between Venice and the Ottomans they were much shorter ranged and had to be accompanied by a land conquest to seize coastal bases. Greece to Italy was about their limit.

Thanks for the info in any case.

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Originally Posted by Gilles de Rais

I know of that but I thought it was the 'Veniti' tribe (in Brittany/Normandy) which gave Ceasar a headache? And while I can see in wiki a Batavian revolt with some Navy action, there are no description of Batavian ships. Would you mind having a look around and link something a bit descriptive?

Well yes, but the state of tribal names of Germanic tribes is inherently confused. the Romans neither understood the barbarians properly nor made any real effort to, and you often get weird results. One of the histories cites a Gallic king as being named Bellorix, for example, but this is actually a title, war leader, and so the real personal name has been lost.

My understanding is that the Veniti were a subset of the Batavians, but that could easily be wrong. I'm afraid there is pretty much no information about their ships; Ceasar's is the only first hand account and he doesn't discuss those sorts of details. But the type of vessels the Saxons used for their invasion of Britain are quite similar to the Viking ships, and it is a reasonable assumption that all the north european coastal Germans used similar design principles.

Quote:

Their slave-based economy, as you pointed out, did not favour technological innovation...

Not just that. As Rome: Total War put it:
167 BC: Rome expels Greek philosophers after the Lex Fannia law is passed. This bans the effete and nasty Greek practice of 'philosophy' in favour of more manly, properly Roman pursuits that don't involve quite so much thinking.

Originally Posted by contracycle

167 BC: Rome expels Greek philosophers after the Lex Fannia law is passed. This bans the effete and nasty Greek practice of 'philosophy' in favour of more manly, properly Roman pursuits that don't involve quite so much thinking.

Had not been aware of that!

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Quote:

Is it possible to build galleys with the clunker method? The wiki for galleys seems to suggest it was actually done (then again, they tend to include longships under 'galleys', which is pushing the definition, I think). And would that radically alter the dynamic of the ship on the oceans?

You certainly could but then they would be longships and not galleys

The big problem with clinker built ships is precisely the flexibility which is the longship's advantage. This flexibility makes it difficult to build hulls capable of supporting solid decks and superstructures, like those for carrying cargo or cannons for example. That is why very quickly as trade, rather than raiding and conquest, became the big thing in the North that clinker built ships were replaced by carvel built ones. And while the planking scheme is similar, in that the planks are aligned edge on rather than over lapping, the northern version used heavy ribs that have the planks directly attached. In the Mediterranean, even to this day, ships are built where the planks are tennoned together and the ribs added AFTER the hull is built. Needless to say that doesn't scale up very well and for large ships the Med shipbuilders eventually adopted the carvel system as well.

Quote:

Would a low freeboard not be a disadvantage in the case of rough seas? I am asking because Wiki (again) cites the higher freeboard of the carrack as an advantage for ocean-going...

Freeboard is certainly an advantage in rough seas, presuming the hull is reasonably secure from damage. Once you pierce it for oars you loose the benefit. People who have sailed in reproduction longships often comment on how little water they ship from the seas even in rough conditions. The carrack and galleon, even the galleass', were much larger ships capable of carrying much heavier cargoes and armaments and since rowing was not the main form of propulsion the high freeboard was not a hindrance.

Quote:

I understand the issue with hogging/sagging and the dilemna with rigid vs. flexibility. Could the fact that the galley had a tendency to hogg be compensated with a more rigid hull? Or one with some ballast?

Sure could, the Galleass is just such a ship. They were useful as an interim step, but they were neither "fish nor fowl" and they tended to combine the worst elements of both a pure sailing vessel and a galley. Eventually as technical skills improved shipbuilders just gave up messing with oars and went for sail only.

Quote:

Btw, I am asking all that because I am trying to establish how the Greek/Roman Empires (if they had not collapsed) could have sent ships across the oceans give or take a few more centuries of development...

Cool...

I suspect once they began to move outside the pillars of hercules they would have gone along the same path as what eventually happened anyway.

F

__________________
"Patriotism means being loyal to your country all the time and to its government when it deserves it."-- Mark Twain

"Inter arma silent Musae"--when the weapons speak, the muses fall silent.

An't nanum hearm deth, doth hwaet ye willath.

It is forbidden to kill; therefore all murderers are punished
unless they kill in large numbers and to the sound of trumpets. -Voltaire

Economic Left/Right: -3.88
Authoritarian/Libertarian: -4.36

Thanks for all that info. I think I am going to say it's some form of galleass and be done with it.

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Quote:

After the tribes already described the rest belong to the Belgae, who live along the ocean. Among these are the Veneti, who fought the naval battle against Caesar. ... They make their boats with broad bottoms and high sterns and prows, on account of the ebb tides. The material is oak, of which they have a large supply, and therefore they do not join their planks closely, but leave openings which they stop up with seaweed, so that when the boats are in dock the wood may not dry up for lack of moisture, the seaweed being naturally rather moist, while the oak is dry and without fat."

This is apparently by Strabo, the cite I've got being "Teirney, 267". All in all it sounds like a clinker built ship.

In the addition, the book I'm reading - the Everyday Life of the Pagan Celts, Ann Ross - which mentions this also has pictures of Gallic coins showing ships that look like longboats - horse- or dragon-headed at either end, central mast.