How is ramming damage calculated?

When one ship rams another, how is the damage or survivability calculated for both ships? I've seen some instances where both ships were destroyed and others where only one ship was destroyed.

Solution 1:

During collision it substracts FULL hitpoints of the weaker ship from both of them. So, if Benson having 2000 HP of the full 15 400 hit an enemy Yamato, it will sink and damaged Yamato for 15 400 HP.

It is applicable in case of collision with friendly ship as well, but the damage speed is greatly reduced so you'd need to scractch friendly ship for minutes before it got substential damage.

The only way to modify the ramming proces is a signal "Hotel Yankee" that reduces damage taken by 20% and increases the damage dealed by 50%.

Hence, if you are on the low-HP battleship, ram is a best way to destroy a full-HP foe battleship.