How to quickly regain sonar contact on a U-boat

This guide shows you how to quickly regain sonar contact after a depth charge pass (or any time you lose sonar contact on the U-boat for any reason).

Introduction

I've been seeing a lot of posts complaining about the difficulty of losing the U-boat after making a pass and failing to find them again with the sonar.

I've perfected a method that works every single time, and it doesn't matter what direction the U-boat goes or how they maneuver. Now this is what works for me. I'm not saying this is the only way to do it, and I'm sure the US Navy had their own tactics.

So here's a (hopefully) helpful graphic I made with my awesome Microsoft Paint skills:

Graphical Example

(link to bigger version - https://i.imgur.com/KhkIn6q.jpeg)

In this example, your destroyer is tracking the U-boat with sonar. The U-boat is traveling north, and you're approaching it from its back-right side with the intent on making a drop as it continues north.

As most frustrated captains know, it never continues in a straight line, and will make a hard turn (left in this example) that you can never follow which ultimately results in a loss of sonar contact. What to do?

1. Select sonar relative bearings

Set your sonar to relative bearings (this is one of the first things I do when a mission starts).

Why? The benefit of having relative bearings in the sonar screen effectively turns the sonar display into a top-down view of your ship. The 12 o'clock position is your bow, 6 o'clock is the stern, 9 o'clock is your port side, and 3 o'clock is starboard.
This lets you quickly set your search pattern immediately based on the orientation of your ship, instead of determining what heading you're on, finding that heading on the wheel, and trying to set your search pattern.
Don't do that. It takes too long.

2. Set the sonar arc

Set the arc on the side of your ship you passed the U-boat on. The 180 degree arc works best.

We set it like that because we're going to turn in that direction to help the sonar in its rotation to reacquire the U-boat.

3. Place initial sonar beam position

Place the sonar start position on the 9 o'clock position, and set the sonar rotation direction. If you're turning left, it will rotate counter-clockwise. If you're turning right, it will turn clockwise.

The reasoning is you want the sonar rotating in the same direction you turned your destroyer. This will speed up the ground that it covers, and ultimately speed up regaining sonar contact on the U-boat.
The sonar is initially placed on the beam of the ship (beam = the 3 & 9 o'clock positions). In the example, it's placed on the 9 o'clock position because you're turning left.

What does this all do?

In the example in the graphic, the destroyer is turning to port, and the U-boat is also turning to port.
The sonar search arc is set to the port side of the ship, and the sonar slider is placed on the 9 o'clock position, with a counter-clockwise rotation.

As the destroyer starts turning left around the last reported sonar contact position, the sonar beams will begin to fan out and rotate counter-clockwise towards the stern of the ship (they're numbered 1, 2, 3, 4, 5, and 6 to show the sequence of beams as the ship turns).

Eventually, one of these beams will find the U-boat. It might be a little sooner or later, but usually when the sonar slider gets somewhere around the 7 o'clock position of the sonar display, you'll regain contact.

What if the U-boat turned the other way? You would just do everything except turning right, setting the arc on the starboard side of your destroyer, setting the initial sonar position on the 3 o'clock spot, and having it turn clockwise towards the stern of your ship.

Advanced Tactics

The above tactics are to regain contact as quickly as possible. However, you may not be in the best position to make another run on the U-boat. Depending on how hard the U-boat turned or if they even reversed their turn, you could be too close to effectively drive your destroyer over the U-boats path.

One tactic you can use is to open up some distance before you regain sonar contact. This is done simply by turning in the opposite direction of the direction the U-boat turned.
In the example, instead of turning left, you could turn right (while the U-boat continues left to the southwest).
Turning right would increase the distance, and give you more turning room to come around and make a run. Just remember to set your arc and initial sonar position based on which way you turned.

[DaveA1963]

Thanks for this! Should be a big help.

[Lord Gronor]

I'd like to make another suggestion that works well - before every engagement, reset your DRT and OSC, and ensure your DRT is in 1:100 mode. After each run on the submarine, reset your OSC to clear clutter. By examining the DRT, you can really easily see the course that the submarine was taking when you lost contact and you can pretty easily pick him back up with sonar.
I'd also recommend turning in the opposite direction of where the sub was going. If he was going to your left, turn right. It'll take longer to reengage but you'll typically have a much better engagement.

[cocolasticot]

It is also possible at the start of an attack, and this proves very effective, to place another destroyer at a reasonable distance from the U-Boat with a sonar search zone 180 corresponding to the location of the enemy boat. This ally will make regular reports on the contact's position and will allow you to find it quickly in the event of a change of direction.

[Cora]

Thx and maybe I can add something I do.
If you' have anaother distroyer that can help you:
Put it between the convoy and you (+the U-boat) and let it scan in your direction.
That way the assiting Destroyer will keep you constantly informed about the U-boats heading and distance from you !
(Keeping your assitant on a certain distance and relatively close to the convoy also is a kind of second line defence if needed and it thereby minimizes the change of a collision with it, wich will always be there if you let it assist you directly in the attack itself.)
A variant to this is to take turns between you and your assistant, so the U-boat is constantly under attack (and not tempted to surface and attack one of yours)
.
(Of course these kind of tactics might be inpossible to use if the total combat situation is more complicated, such as being under attack from multiple U-boats and /or having only few destroyers available.)

[tayler15]

Love to see more Guides on Tactics. It is good that destroying U-Boats has obviously been made very difficult and a little help would be appreciated.

[DTDZOD]

echo location that doesnt echo is not how sonar works
being able to hear the return ping bouncing of the enemy sub would be nice
you know like a real sonar!

[goot loblin]

I find it easier to use the DRT and DSC projector (assuming autoplot enabled) with true bearings because, unlike relative, true lets you sweep a specific compass wedge regardless of ship orientation. If you, course 180, drive over a contact while attacking, you can order a sweep centered on 000 and your sonar operator will likely reestablish contact well before you've gotten the ship turned back around, letting you set up for another attack more quickly.

Nothing wrong with the guide, though! Relative's definitely easier to wrap one's head around and is extremely handy when your brain is on fire because too much is happening.

[Phantom]

Well done. Thanks.

[OVARIAN BARBARIAN]

very well done sir.

[Hammer]

You must think like a submariner. What would you do if a destroyer is hunting you. This will enable you at least gain an advantage in 'boxing' your attack and eventually get a kill.