Mass/weight of a triere

[Praefectusclassis]

Displacement of the Olympias was about 44 tonnes, including a crew of 200:
J.F.Coates, 'Carrying troops in triremes', in T.Shaw (ed), The Trireme Project. Operational Experience 1987-90. Lessons learnt (Oxford 1993), p.78. The same book has an article with some calculations about the required speed vs angle of attack to break the enemy hull: J.T.Shaw, 'Steering to Ram: The diekplous and periplous', ibidem, p.99-104.

[P. Lilius Frugius Simius]

Great comments... I got the 70 tons from the Wikipedia entry on the Olympias, I guess it's wrong?

As for the weight of the crew, though, yes, it's 14,000 Kg (I added 10 tons to the Olympias number, so I was going in the right direction, but wrote it wrong on the post... :-)

I don't think the trierei would be able to carry a lot of cargo, but one day-long travels were common, and considering they were rowing in the Summer, you could easily need about 5 L of water per men and per day. We know that Alexander managed to force the defending Fleet at Ephesus to retreat for lack of fresh water after three of four days (or am I thinkning in the wrong Ionian siege in here?).

That means 10,000 L per ship per day. Even if you try to get the water dragged as long as possible, and a sieging Fleet wouldn't be rowing, it's still a lot of water (and 10 more tons of displacement in morning, until the sweating and Nature calls get the most off the ship... :-)

Even if the over all displacement is down to 60 tons (40 for the ship, 14 for the crew and weapons, and 6 for water and food) the numbers are pretty much astonishing... (multiply all my figures by 0.75)

p ~ 2e5 kg m/s at ramming speed...

Still a lot!!! (Our 1 tm car would still crash at the astonishing speed of 720 km/h ~447 miles/h!)

The violence of the crash is important as I recall reading that many Spanish ships in the Felicessima Armada managed to dissassemble themselves by using their cannons on sea battle, when most of them were modified merchant ships carrying weapons designed to use as land siege cannons! If the triremes were so "delicate" as to needing being berthed on land as often as possible, it was probably because they suffered heavy damage to the wood planking on every ramming maneuver, and water could start pouring in if they weren't taken care pretty often (besides, pinewood is light but bends more easily than oak or teka...)

As for the red-hoy sand, it's certainly incredible, but I have a hypothesis to try and explain that: as the incredibly hot sand was poured on the iron shields, they quickly dissipated some of the heat (after all it's a good heat conductor), fast enough to avoid reaching melting point, and fast enough so the colder sand shielded it from the hotter one. I.e. the iron got hot by cooling the sand that got in contact with it, and that cooler sand, being a very bad heat conductor, protected the shield from further damage by keeing the red-hot sand away from the iron. As they would be handling the shields with pretty good caw hide gloves, anyway, the operation was probably done as fast as possible (I mean, 1,400ºC is a lot of heat, and an aspis could easily hold several kilograms of it, which is a considerable source of heat and discomfort...). One can even envision the inside of the shield to become covered by a glass coating of melted sand...

well, just my €0.02 cents!

[Praefectusclassis]

ACtually, it was found that the rowers on the Olympias need around 10-12 liters of water/day. Hot work then! Every rower probably took his own little amphora on board.
The essential question here of course is whether they rammed at 'Ramming speed!' (think of Ben H. here) or not...

[hoplite14gr]

Athenian navy was well trained in triky manuvers and proved it during the Pelopenessian war in Rio. Also equipment was well maintained.
The Megarean fleet for lack of funds and men was rotting and a daring raid in unprotected Athens was canceled for that reason.
Navy of all times is a "technical" complex weapon and needs lots of effort to be maintained. Athenians made that effort. Their enemies usually did not.
And remember Aegos Potmaoi was aploy not a naval battle.
Kind regards

P.SRoewrs caried watersjins not amporae!

[P. Lilius Frugius Simius]

Jasper,

10-12 L of water a day per rower??? That's even more weight that I expected (twice as much as I used on the last row of calculations)... we are starting to get closer to the 70 tons of weight for a "full rigged", full manned trireme...

Yes, the ramming speed is the key to all this dance of numbers... I am 100% positively sure that the speed needed to perforate a trireme hull wasn't very high at all... With all that inertia, an attacking ship would surely need only a small speed to crash a hole on your lower hull and sink you.

Therefore the speed was only used to get there, and not to allow you to escape. Once the collision was inevitable, I am sure the speed would have been lowered as much as possible...

We can make another exercise, it will be especulative, but it will help us to have a better idea of the dimensions of what we are talking about in here...

If we take a trireme of 60 total tons at 7 knots speed v0 and stop rowing, in ideal conditions of calmed water and no wind, we can try to approximate how long it will take the ship to stop herself, and how much space does she needs. Unfortunately the formulae will need a lot of approximations, and its confidence, therefore, low. But as a 1st approximatio it will have to do... :-P P

Drag force for an object on water is proportional to the speed, -bv, where b is a constant that depends on the water density and object's shape, and v the speed.

Therefore, F = m a (approximating zeros...) => v = v0 exp(-bt/m) and the distance to stop will be x = -bv0/m

Now, the trouble here is finding a good enough value of b... Let's consider the trireme a huge kayak (OK, this may be a bit too far-fetched, but...). Experimental measures thrown a varying distance to stop on quiet waters and low winds for a K-4 kayak of 50-100m from cruise speed (about 10 knots) down to "zero"... Considering the K4 has a ICF max. length of 11 m (and a min. displacement of 30 Kg), thus we find a "penetration distance" of 5 to 9 times it's length.

If we get b from here, it gets: b = (40 + 4*75) kg * 8 * L m / 5.15 m/s ~ 5281 kg s

Thus, we get a squeashy value of "penetration distance" at 7 knots for our trireme of x = b * v0 / m = 0.32 m (this is, it would crash against the water like if it were concrete). However, this means that the semi-time (the time to reduce the speed by 1/e) is 11.36 s, this is it would be moving at less than 1 knot in about 25 seconds (which is almost completely stopped) and it would take about the whole length of the ship (35 m) to stop...

This actually means nothing, but we can conclude that a trireme had an enormous drag, and that the length of the prow ram was significantly smaller than what the trireme could ram by its own inertia: slowing down a bit makes perfect sense, specially considering the difficulty to get the ship moving from full stop (my kayaking sources point to the most difficult thing of moving the craft)...

OK, doubtly useful, but fun and illustrative, nevertheless... :-) )

laters!

PS- data from Olympias are also posted here: http://www.mlahanas.de/Greeks/war/Trireme.htm and displacement is about 45,000 kg...

[conon394]

Jona Lendering

I think that smashing the oars is sufficient to disable an opponent, so ramming is not really necessary. It is interesting to see that the first naval battle Thucydides describes, Sybota, is, as he calls it, "old fashioned", i.e., without ramming.

I don’t know that Thucydides meant to imply no ramming, but rather just the opposite. The ‘new’ or ‘Athenian’ fashion was essentially very nearly exclusively one of ramming.

[Jona Lendering]

Jona Lendering

I think that smashing the oars is sufficient to disable an opponent, so ramming is not really necessary. It is interesting to see that the first naval battle Thucydides describes, Sybota, is, as he calls it, "old fashioned", i.e., without ramming.

I don’t know that Thucydides meant to imply no ramming, but rather just the opposite. The ‘new’ or ‘Athenian’ fashion was essentially very nearly exclusively one of ramming.

It is possible that we misunderstand eachother. Thucydides means that Sybota was an old, non-ramming battle; he is explicit that diekplus was impossible and describes it as an infantry battle with spearmen, archers, hoplites, et cetera. It is only at the end of the battle, when Athenians do actually get involved (something they had avoided), that ramming occurs.

[Titus Martius]

I would like to highlight that ramming impact was taken not only by ram but by wales - strong wooden timbers running alongside at sea level full length from bow to stern - wales are very important construction strengthening members of the hull.

I suppose P. Lilius Frugius Simius is correct that ramming was done by much reduced speed since impact with 9 knots might be disastrous for attacker, too. The ramming ship may simply slow down by taking in the oars just few seconds before the impact, let say the crew could do it in 5 seconds, so the travelled way would be some 20 m. Crew on ramming ship should lie down to protect themself from injury caused by impact. Such a small speed as 2 knots is enough to penetrate the wooden planking with ram, since the inertia of 40-50 tons is transferred to a very small area of ram.

[P. Lilius Frugius Simius]

P. Lilius T. Martio sal!

Avete!

You are, of course, perfectly right. Not only the hull was reinforced by the wales to help absorb the impact, but I am sure the whole of the ship's prown was reinforces as well at the skeleton level (probably the beams where specially attached in order to make the prown sturdy and resistent.

The point here is that a full speed crash was probably the wrong thing to do, and a perfect way to suffer almost as much damage as your enemy itself (impact damage aside, the time you'd need to detach yourself from the sinking, enemy vessel, must have been long enough for the toxotai and epibatai and a good deal of rowers among the thranites and even zygites orders (upper and middle levels) to assault on the attacking vessel and give more headaches than were probably worth.

Of course, as you point out and clearly show on our beloves Olympias, a ramming ship was prepared to resist the stress associated to the ramming itself, (which is logical if you just think about it).

Thanks for the tip (no pun intended)!

vale!