Weird radar behaviour
 

[Fotrsu] On patrol, I detect on radar a convoy approaching. After determining speed and course, I turn off the radar as I move to intercept. However, when the convoy is about 11 nm (or kiloyards - I can't remember) away, I picked them up on radar again even though my surface radar was still off.
What gives?

Fletcher Christian is on board? :haha:

Which radar did you turn off? What date is it? Later in the war, your radars kind of "merge" together with the SV able to pick up surface contacts, and the SJ-I able to pick-up air. Also, are you sure it was radar? Do you have an APR-1 RWR device on the boat? As B9 Robot said to the doctor "Does not computer" and another famous sci fi robot or computer or conehead said "need more data"...

You are in the Tench I assume (you were asking about Tench other day) ? If have SV radar, SV was air search and could detect surface targets as well. This was modeled in the sim but became a pain because A could not sure it off (luckily in FOTRS you can turn it off) when needed to.

In TMO, I modeled it to be air search only as it was redundant.

Yes this is a Tench boat. I can't remember what I have exactly but its all the bells and whistles.

Most likely the SV radar as explained or if I recall, in FOTRS they have ST radar (radar in periscope, which some boats had, did come standard on Tench as a late war build). Was basically a small radar in attack scope to give instant, accurate ranges for firing vs. stadimeter. Tench in TMO has it was well but only the Tench. but if SV if off, then it is probably the ST, which don't believe can be turned off.Not sure if works unless scope is extended. Propbeanie can fill in the blanks .

Hmm. I was approaching another convoy off Kyushu, determined speed and course, turned off both air and surface radars and manoeuvered to intercept. And some later as the ships got back into range "radar" (which had been turned off) picked them up.

There are three radars on the Tench. Which one are you turning off? The "T" key turns off the SD, the "Ctrl-T" combo turns off the SJ and ST (periscope). You also have an APR-1 RWR receiver, and if you have identified a "ship" via radar, then receive a radar signal from them, your APR will also show that "ship" icon. If it has not been recently identified, the APR-1 will generate a line, similar to sonar, toward the signal received. It is not "odd", but rather "normal" behavior.

Both radars are off (T, ctrl-T). I'm not sure if it's the APR as there was no line displayed.
Still puzzled over this but no matter.

You don't have your FotRSU mod list, so I'll assume you haven't added anything. Either way though, the game itself can only do one sensor at a time. The game will always use the "preferred" sensor, so if you have visual contact, you will "see" the asset, but not have a radar image, nor sonar line. If you do not have visual, but you do have radar, you will see the radar "reflection", but no sonar line. If you are on the periphery of the range, and the radar "reflection" fades between sweeps, then you'll see the reflection, then a sonar line, then another reflection as the sweep comes around (if the beam picks it up), then sonar again as the radar fades. The sonar can reach out further than the radar (usually), so if you do not have a radar contact, then you would see the sonar line only.

Now, if you add the RWR APR-1 receiver into the equation, it has a "line" like sonar also - but only when you have not established contact previously, or if you have been out of contact for a certain amount of time. I do not remember what that "time" is in FotRSU off the top of my head, nor do I remember where that is set without doing some deep digging. What would happen though, if you have established radar contact, and then move far enough away to temporarily lose it, and that particular contact also has radar (the AI assets in-game always use their radar, if equipped), then you would have an activated APR-1 "contact", and since it has already been established what that contact was, the game will use the "ship" icon for that target that emits the radar signal. What I have found occasionally, is that if an airplane happens to come across that same bearing at a similar time, the APR-1 has mis-identified the contact as a ship for me, and then roughly 3 minutes later "Aircraft spotted, sir!" "We're under attack, sir!" BOOM "We're taking damage, sir!" "We have heavy flooding, sir!"... So a person does want to be careful with those type of contacts. But that is the beauty of the APR-1, in that you can turn off your radar, and still have a "contact" that you can track. Now, if you do NOT have an APR-1 onboard, then you would indeed have "weird" behavior".

Part 2 of the APR-1 is that if you have "color" lines (ala with "450_MoonlightzSonarLines" activated), you will then have "blue" lines for a warship sonar contact, "black" lines for a merchant sonar contact, and dark "green" lines for an APR-1 contact. Likewise, you would notice a difference between a visual contact with red for "enemy" and blue for "friendly". There is a slight difference between a radar contact, being dark grey, and an APR-1 contact of light grey, which is somewhat similar without Moonlight's add-in.

It'd be better to have your mod list, date and boat - which was a Tench in another, previous posting, correct? So it should be 1945, which would indeed have an APR-1 onboard, and would explain your "maintaining" what appears to be a radar contact - because to the game, it basically is a radar contact. So mark it on the NavMap before it disappears on you... :arrgh!:

just started new 41 game. past, I always shutoff radars' when entering port, to stop annoying contact reports. still get them.