Mass/weight of a triere

[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!