Title says it all. I usually go as close to the target as possible (400~500m) because any distance more than 800m I tend to miss.

Is it normal to fire at such distances or do I need more practice with precision? Also, any history buffs know what distance the actual U-Boat commanders kept with their target?
And just one more question on the side so I don't have to start a new thread: Does pinging for depth under keel give your position away to the enemy close by? I have a habit of pinging for depth before hiding from destroyers and those bastards always manage to find me somehow.