@terryn
What friendly forces will do ?
If they are warships, When they reach the ambushing area, they will start attack with no hesitation when they find out there are enemy in the region.
If they are submarines, they will starting dive when they are in the enemy’s region range(about 8km) , and then they will gradually close to enemy, then they will shoot torpedo when enemy’s distance and angle is appropriate. After shooting torpedo, the next round needs to measure and fill again, this process will cost about 20~120 seconds. If find enemy accidental when friendly forces’s submarines haven’t dive , they will use artillery and machine gun to attack enemy like warship do so , if angle and distance are not bad, they will shoot some torpedo occasionally.