AGILITY

 

There has been some discussion on the net about Hotz Roman Seas Rules, especially their movement section. A lot seems to depend on interpreting how ships accelerate or decelerate. I don't have these rules because I don't like hex-based games. One point of discussion seems to be the opinion that galleys take a long time to stop in the water. My experience with viking galleys says this is wrong. The point to consider is that there is a tremendous amount of power in the propulsion system compared to the ship's mass and this propulsion system is dynamic: each side or individual levels can be put in reverse, stopped, or slowed.
 
Olympias could accelerate to 6 / 7 knots from a standing start in 30 seconds (making about 1,5 ship lengths) and could stop in about its own length from full speed of c.6 knots. (Athenian Trireme, Coates et al. 2000). This with an amateur crew.
Galley combat relied upon agility, with experienced captains and crew darting at each other and swerving and jinking to avoid collision. Collision would only be allowed to happen when conditions were right to achieve a deadly blow (or by accident) otherwise the attacker could be caught in the flank when stopped or as he reversed. If there were any complex considerations about deceleration curves or response times these tactics would not work.

Looking at the power/weight relationships of the various galley types one can see that a) the variation is not enormous 2) The trireme is supreme in the pre-Roman era and the Liburnian is small but extremely agile which goes some way to explain its supremacy in the Roman era. The viking Ladby ship is there for comparison. A fully loaded later viking warship may be much heavier with half as many oars again.

TYPE	OARSMEN	SHIP-LOADED WEIGHT	OARSMEN/TONNE
TRIERES	170	48 TONNES	3,5
HEMIOLIA	54	17.5	3,1
TETRERES	180	56	3,2
TRIHEMIOLIA	120	40	3,0
PENTERES	300	110	2,7
HEXERES	360	125	2,9
LIBURNIAN	54	10	5,4
Pentekonter	40	15	2,6
Bireme	48	15	3,2
Ladby Skibet	48(60)	6(15)	8(4)

(Data from 'The Age of the Galley' : Conways history of the ship)

Once Rome dominated on land its only opponents at sea had smaller, agile vessels which a 4 or 5 could not deal with but the liburnian could. The viking ship or pentekonter stand for 'tribal'  or pirate ships. Here one can see why larger ships were dropped in favour of the model which was not only seaworthy but nimble enough to tackle threats from raiders rather than a challenge to Roman might.

The main point is that it needs a good appreciation of the ancient ships' capabilities to make some realistic rules which at the same time need not be overcomplex.