Green rings& ASW helis

[innocent_bystander]

Question 1: what are those thick green dim rings around naval vessels?
Question 2: how do you take advantage of convergence zones (from a subs and ships perspective)
Question 3: Why ASW helis fly 3800m above sea when on ASW patrol? Arent they supposed to fly as low as possible?

[Sakai007]

1. I do believe those are the passive sonar detection ranges, these normally show up on ships/subs equipped with a towed sonar array.

3. I do believe they do that to take advantage of increased height to increase radar coverage. Those radars can pick up a subs periscope as well as surface vessels. And while assigned to ASW patrols, they will stop and go down real low to use their dipping sonar, as well as drop buoys if equipped.

Hope someone else can help with #2.

[Dimitris]

ORIGINAL: innocent_bystander
Question 1: what are those thick green dim rings around naval vessels?

These would probably be the CZ rings/donuts.

Question 2: how do you take advantage of convergence zones (from a subs and ships perspective)

Depends on whether you're the hunter or hunted. Roughly speaking, if hunting you want the target(s) to be inside these donuts if possible. If they manage to get between your unit and the first CZ ring, they're going to be invisible to you until you make direct contact with them, which can be pretty close. (This BTW is the source of many of the "my ship/sub is not detecting this sub/ship" bug reports we get; players drop the target smack in the middle between direct-path range and the first CZ ring).

If you are the target, you want to avoid being in these rings as possible (or go _real slow & quiet_ when you are) and sprint like hell when you're not.

Question 3: Why ASW helis fly 3800m above sea when on ASW patrol? Arent they supposed to fly as low as possible?

They move at best-economy throttle/altitude while transiting between sonobuoy/dipping-sonar legs (also to maximize sensor coverage as Sakai pointed out), and descent once they reach the desired point or when they want to employ an ASW weapon.

[innocent_bystander]

Thanks for the answers! I've learned something new [:D]

[innocent_bystander]

Oh, another thing: at which depth setting do you pick up contacts from CZ?

[mcp5500]

A convergence zone is the ring that represents sound traveling down from shallow water of the ring. In deep water sound waves traveling down through water is bent by the increasing pressure until the sound wave starts up towards the surface where it can be detected by your sonar gear. It bends the sound until it rises back up to shallow water. The sound can then bounce off the Thermal layer or the surface and start downward again to give you a second green ring and so on. A convergence zones are 30 to 33 miles. You can detected them below a layer if one exist or at surface. CZ require a minimum depth of about 400 meters in order to form