Question for WernerSobe or other Guru.

[brandtryan]

I've learned a lot from your tutorials, and have even bagged an enemy using hydrophone only in bad weather! However, I'd love to get some advice on isolating contacts on the hydrophone.

My dilemna: I'm trying to setup an attack on a merchant, say one amongst many, and escorts--specifically trying to get the speed by using the 15 minute method, taking positions/marks every five minutes, then dividing total distance travelled by 15, then multiplying by 60. My problem is making sure I'm getting positions on the SAME contact throughout the 15 minutes! Does this make sense? I often wonder if I'm using the wrong/different contact on hydrophone that what I had started off with.

Anyone feel free to reply!

[skwasjer]

If you are tracking a convoy, you can pick up the lead contact on each measurement. In convoys, every ship travels at roughly the same speed. Even if there are escorts in front zigging and speeding up/down, it's overal speed is still roughly the same as it tries to maintain a fixed distance to the rest of the pack. It gets a little bit more complicated if they know you are around and escorts start weaving out to the sides though. Also, your relative position may cause problems using this method (ie. if you overtake them, another ship may become lead contact).

You can try to take over the hydrophone yourself as well, and listen for the first merchant it's screws, which rotate significantly slower. Again, pick the first contact and mark him. Alternatively, I've heard people count RPM to have a rough estimate of target speed (using a RPM/speed table), but I don't use this myself.

After you got a speed estimate, you can be fairly sure the other ships in the convoy travel at the same speed. So, in short, track the first contact.

I'm not a hydrophone guru, but I use this method alot.

[brandtryan]

Thanks SK--that all seems to make good sense.