Opposed river crossings

[TheDoctorKing]

Just a basic informational question: what is the current state of the rule on crossing a navigable river where there are enemy naval units? How many elements to block crossing? Do they have to be in offensive mode or is defensive enough? How about if you have naval units in that river zone as well?

[Primasprit]

Ships blocking troop passage over the river have 23% chance per ship to block the passage up to 90%. Any non-passive posture.

[briny_norman]

How is 'passive posture' defined?
Is a defensive posture passive?

[arsan]

How is 'passive posture' defined?
Is a defensive posture passive?

No, passive posture is well... "Passive" The green button by the blue defensive one.
So you can put your boats in defensive posture and still interdict crossing.
Cheers!

[Rafiki]

All you want to know about posture: http://www.ageod.net/aacwwiki/Posture

(Or significant parts of it, at least )