TB-23 operation in LWAMI?

[Pillar]

I've been doing some tests using a 688(i) with LWAMI 3.09

I understand the TB16 is the port array and the TB23 is the starboard array in this mod, and that the TB23 is supposed to be midway in performance between a TB16 and TB29.

The odd thing is that I am getting 60hz tonals from about 60nm on the TB16 from a container ship running at 15 knots, but my TB23 when deployed doesn't get any signal at all. I even get bow sonar readings without the TB23 picking anything up.

What am I seeing here?

Edit - I apologize if this is in the wrong forum

[TLAM Strike]

The 23 is longer so maybe its dragging under the layer and thats blocking the signal.

[Pillar]

Maybe. I ran some more tests tonight and it was working ok. I was at about 70 feet with the array fully deployed but only doing 3 kts. Layer is at about 850feet. I'm not sure if it would drop that far with those parameters or not.

It might have been something to do with the autocrew not picking up the signal, as well. Not sure.

How much closer does a target have to be for the TB16 to pick up after the TB23 might? (rough distance difference... in something like default sea state (3) and rock/surface duct conditions.) Is there a big difference between the arrays?

[Molon Labe]

In those conditions, the difference should be enough to notice, but not huge. I'd guess that the difference is about 2nm for a relatively quiet contact. If you're using autocrew though, all bets are off.

[Pillar]

Under what conditions does the disparity between the TB16 and TB23 or TB29 really show?

[Molon Labe]

Well, the gap between the -16 and the -29 is pretty significant, you should be able to see that just about anywhere. The -23 is right in the middle, which is why it isn't as obvious of a difference. Where is it the biggest? The conditions you tested them in are at the high end. You might see a bigger difference in a CV SSP with minimal sea state, but inside the upper layer in a duct SSP is going to be about the same. I guess the point is that the -29 is only marginally better than the -23 and that the -23 is marginally better than the -16.

[TLAM Strike]

Maybe. I ran some more tests tonight and it was working ok. I was at about 70 feet with the array fully deployed but only doing 3 kts. Layer is at about 850feet. I'm not sure if it would drop that far with those parameters or not. Don't go searching the sonar at 70 feet. Your too close to the surface, and all the wave action clouds your sonar. Go from PD to below the layer at about 5 knots and watch the BB sonar, your see what I mean.