The measurement in my shipmodel from oarlock to oarlock is 14mm.
Though I am aware in the old literature a space of 1 meter per rower is usually given which should be around 12mm.
I had two reasons to add extra milimeters.
Most important is my figurines are too big. They simply don't fit into a 12mm space, which I discovered when I build my first rowing boat.
Like most other 1:72 figurines, mine are between 23 and 25mm instead of between 20 and 23mm.
Also I read a theory making a difference between a wargalley and a merchantgalley.
For the wargalley like Olympias every centimeter of space reduction is advanteous in an attempt to cram as much musclepower in a shiphull as possible.
With a merchantship, this was less important since such wide hulled galley was not very fast anyhow and did not have to ram an enemy ship.
I designed this ship with the 'start of stroke rowers' in mind. Most of them fit banks, oars and feetrests pretty well.
The 'end of stroke rowers' fit too. But less perfect. Also their arms position must be lowered. Which is possible since its soft metal including partly separate arms: