Mass/weight of a triere

[Jona Lendering]

Does anybody know how heavy a classical triere was? And its maximum speed?

[Praefectusclassis]

Speed: there are a few reported - as extraordinary, probably, trips. Giving between a little under 6 knots till 7+ knots an hour for cruising speed. Ramming speed was around 9 knots (but the Olympias never made it for longer than a few seconds).
Battleweight, iirc, is around 40 tonnes, with the crew making up around a quarter which explains why a galley with a lot of marines on deck would often be of a type that is wider at sealevel to give more stability. If you need more exact info, I can look it up, but I think the relevant book is at university.

[Jona Lendering]

Which means a momentum of 180.000 kg m/s. I'm now going to call a crash test lab.

[hoplite14gr]

Please check
http://www-atm.physics.ox.ac.uk/rowing/trireme/
http://www.hellenicnavy.gr/trihrhs_en.asp
http://en.wikipedia.org/wiki/Olympias_(trireme ) (size and speed)
Hope I helped
Kind regards

[Jona Lendering]

Hope I helped

Yes you did. I have in the meantime sent some questions to a crashtest lab. The relevant comparison for the shock that the ship must have experienced (180 000 kg m/s) is that of a small van making a frontal crash against a wall. I wonder how a comparatively small ram can survive this.

Jasper in the meantime wrote me that there is evidence that ships, when they knew for certain that they would ram the enemy, started to row backward to avoid too heavy a collison. Sounds very plausible.

[hoplite14gr]

Well in the naval battles in Syracusae Thukidides says that ships prows were reinforced with wooden beams and thats the reason why Syracusans got the better of the Athenians. And Thukidides had seen action so he knows what is he talking about.
Also execept ramming oar shearing during "diekplous" was an important tactic.
Kind regards

[Praefectusclassis]

Oh, but having a heavy enough prow is one thing, making sure it doesn't penetrate too far into the other hull is quite another. You don't want to get stuck and become a prey for the victim's marines or another triere on the prowl, now do you?

[hoplite14gr]

Hmmm...It depends on the abilty of your marines and you fellow trireme-captains I guess.
Kind regards

[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.

[Praefectusclassis]

Smashing the oars without ramming must have been a crafty and difficult maneuver to execute in itself though... Low angle of attack right behind the opposing ram, retracting your own oars fast and far enough so your own rowers are unhurt, skimming by without actually ramming and getting stuck, then unship the oars again and make sure you don't get rammed by any enemy trieres covering openings in the first line.

[Jona Lendering]

Yes, that is true; but at least you don't get stuck inside another hull...

[P. Lilius Frugius Simius]

My thoughts on this:

Olympias was about 70 tons of displacement, and you had to add some 200 people to it, at an average of 70 Kg per person (healthy, strong, athletic, short people) you have some 1400 Kg more.

Let's say, for the sake of simplicity, that despite the Olympias being made of Oregon pine and Virginia oak (which the original triereis would not, of course) they would have some kind of water supply on board, as well as weapons, food, and some emergency supplies on board.

I think some 80 tonnes as average is a good one average. That's 8*10^4 Kg (or 8e4 Kg).

Top speed rowing is some 9 knots, which is about 4.6 m/s.

p_t = p(v_top) = m v_top = 368000 Kg m/s
p_r = p(v_ram) = m v_ram = m 7 knots = 288000 Kg m/s

Considering the ram was about 200 Kg of mass and some 2-3 m long, we get a penetration force (barring wood resistance) of

F = dp/dt

dt0 = 2 m / 3.6 m/s = 0.555 s
dt1 = 3 m / 3.6 m/s = 0.833 s

=> (obviously, dp = p - q, as in the end we get both ships stop. Actually there would be a lateral movement of the target ship, puched by the attacking ship, but considering this would force us to model water resistance to lateral displacement, let's sunstitute it by a constant q > 0 but presumably q < 1 and probably q << 1, i.e. negligible at this scale)

F0 = p_r/dt0 - q/dt0 = 288000/0.555 - Dq0 ~ 518919 N - Dq0 ~ 5.1e5 N
F1 = p_r/dt1 - q/dt1 = 28800/0.833 -Dq1 ~ 345738.3 N -Dq1 ~ 3.4e5 N

Therefore, the strength of the impact would be about 30 and 50 tons, absolutely brutal (approx. the equivalent of a 1 ton modern-day car crashing against a wall at some 1,040 km/h; 646 miles/h, which is about 2/3 the speed of sound on air: this is really fast!!! An easier image, perhaps, to visualize could be a small train wagon (my town's are about 27 tons each) at some 40 km/h, which is half the top speed of these town trains, or about some 24 miles/h).

I guess that slowing the ramming speed at the moment of the impact had secondary effects, other than helping the ship not getting stuck to the enemy vessel: it would be easier on the ship frame, and it would make faster a retreat (which would start the enemy ship sinking) by creating a back-rowing rythm before the ship started to gain momentum backwards. Additionally, if the ship actually rammed more than the ram, it would suffer structural damage of the prown, which is, obviously, an indispensable part of the battle ship.

I'm with Jasper in that the diekplous must have been hard to perform: you had to take into account both ships speeds and routes, and the time it took your own rowers to get your oars off danger, then how long would they need to get the oars back to the water so you could get away before enemy archers (toxotai) could create havoc on your ship!

I'd say it's a maneuver you can try in battle after some practice. The periplous and other maneuvers simply asked some basic oarsmen skill and coordination between the rest of the Fleet...

As always, doing the numbers is astonishing, don't we love Antiquity? :-) )

best regards!

[Jona Lendering]

I will reply later; I guess you're right, although my estimates are lower.

What is your source for 70 tons? Jasper mentions 40. (Frankly, I always confuse several types of tonnage.)

As always, doing the numbers is astonishing, don't we love Antiquity?

Yes! Here's one from my book on Alexander the Great: during the siege of Tyre, according to Diodorus, the Tyrians put sand on shields and heated them until the sand was red-hot, and after that, they threw the hot sand on the attackers. I asked a glassblower, who confirmed that, depending on the structure and components, sand can not turn red until 1400 degrees. However, iron shields will start to melt at 800. How this is is possible, is one of the mysteries of ancient metallurgy.

[Praefectusclassis]

I may be wrong about the weight Jona. I have the test report on Olympias at university. I'll check. I can say for certain though that 200*70 makes 14,000 kg more, not 1,400. :wink:
Good point about the depth of penetration David. The ram was especially strengthened to be able to take the punch, but the rest of the prow closely behind it, wasn't.

[Dan Diffendale]

Let's say, for the sake of simplicity, that despite the Olympias being made of Oregon pine and Virginia oak (which the original triereis would not, of course) they would have some kind of water supply on board, as well as weapons, food, and some emergency supplies on board.

Don't overestimate the space devoted to supplies onboard. Food was expected to be acquired regularly at friendly ports or via mobile marketplaces supplied by either accompanying supply ships or coastal merchants.