Doh! 20, 000 tonnes :88)

p.s. no, I machine gun the liferafts :arrgh!:

If you ever manage to sink one let me know :DL

Hmm. I didn't think I was picking it to pieces, just quibbling with some details. What you descrbe is a good general approach for sinking tonnage in the game and I just think it would be much better with another WO reading.

I'm going through this for two main reasons.

1) I'm a bit of a fanatic about simulation, and the method you describe was not usually employed, AFAICT.

2) I think it is possible you are overstating the adequacy of this technique.

In fact, I think this will work well enough much of the time, but I want people to be aware of the inherent inaccuracy of one pair of measurements 3:15 apart, in case they think this will do them for all their shots.

You keep statistics of all your torpedo shots? Please tell me you have statisitics for on the order of 10,000 shots, otherwise you can't claim with any validty that it is your method that is giving you the claimed hit percentage. It could just be statistical variance of the cumulative error of the WO reports.

Nope. That's why I waited to do some calculations before I made this post. I realized that the 0 gyro angle shot at close to 90 degrees to target track would not be nearly as sensitive to course measurement error than non-zero gyro angle shots. But I didn't know how much.

Well, I expect that they do affect your hit probabilities, but you haven't noticed. Relying on a single pair of readings 3:15 apart, in a scenario like the one you described can increase your inaccuracy above the inaccuracy expected due to plotting error by 33%. Take three readings, spead over 6:30 and the increase in inaccuracy is only 10%. Does this really matter? If most of your shots are taken at large targets at ranges under 1km, probably not. From the scenario you described, I assumed otherwise.

I agree. So how accurate do you need to be with course and speed before you run into problems?

I ran the numbers for the following situation:
Submarine remains motionless throughout, except to pivot.
Submarine is 1750m from target's actual track.
Target starts 2450m away. (Bearing 46 degrees)
Target speed is 6 knots.
Assume no plotting errors or bearing errors.
You get bearing and range from WO, with range short by 50m from actual, due to rounding.
After 3:15 your get bearing and range again, this time with range long by 50m.
This gives you an observed target speed of 5 knots (nearest whole knot multiple), and an observed target course 8 degrees away from true course.
You rotate to perpendicular to observed course, and fire an electric torpedo when target comes on bearing for 0 gyro angle shot.
You miss the aiming point by 20m, but because there are no other errors, you still hit the target.

Now add in median error due to plotting inaccuracy and bearing precision limits. That 20m error factor is enough to change many shots from hits to misses.

Repeat the scenario except this time take your second reading after 6:30. This time you miss the aiming point by only 6.5m. This is not a signifcant change to the overall inaccuracy from plot and bearing error.

I can't give an exact figure for the difference in hit percentage because there are too many variables: range, initial bearing, target length, target speed...

What I can say is that determining target speed and course from only two readings 3:15 apart can have a significant impact on your miss rate, while adding a third reading after another 3:15 reduces the impact to insignificance.

With that one simple refinement to what you proposed, I think it is a great approach to attacking.

If we have some "good eye" skills, and we play with manual targeting, and our u-boat is in the good attack position alredy [usually 350m - 1500m from target with AOB from about 60 - 110 degree] then we can use periscope as a
hind-side. First we set periscope for bearing 0, then in TDC manually AOB for 0, range for 700m - 800m, and target speed for 0, and after this we push the automatic update button for the "ON" [red setting]. From this time we can use center of periscope as a hind-side. This is very good method when we dont have time for update TDC.

For example. If torpedo speed is 30 kt and we attack C2 which is about 600m from us then we move center of the periscope [on 1x zoom] on the position: about a half lenght of the C2 cargo before C2 cargo and we fire torpeedo. If we have some experience in this then we have very powerfull tactic for some situations.:DL

You must feel the target speed

skookum, thanks!

I've tried your method: 8 torpedoes of 8 on target

I'm not an expert, at all, and maybe there are better ways to sink merchants, nonetheless seing my hits percentage raising from 20% to 100%, makes me a lot thankful :woot:

One technique in bad weather is to take advantage of the convoy's formation.

Get into the middle of at least the first two lanes and cruise backwards until you've got one coming across for a shot from the rear tube at as near to 90 deg AOB as possible. If it gets too close, abandon this shot, if not take it. At the same time fire two eels on a 1 deg spread out into the fog on 0 deg gyro angle shot from the front tubes. If you hit you're rear target you're almost assured of a hit on your front target with both eels.

Personally, at this stage I also take a bit of a random shot about 10 deg (not precisely!) either side of 0 gyro angle in the hope of hitting something else. The random shots do sometimes pay off.

cannot this tecnique be used in calm weather ? (I mean, standing still at depth and waiting for the convoy)

too high risk of detection?

AOB 90?
 

Here's what I don't get about this technique. If you point the sub perpendicular to the target track, the AOB isn't going to be 90 degrees at the time gyroangle is 0, unless the ship is stopped.


.....|--d--|
..ship------------------>
......\ A..|
.......\...|
........\..| <-Torpedo track gryoangle 0
.........\.|
...........^
..........sub

Angle A is the AOB for that ship, d is the distance the ship will move between torpedo launch and interception of the target track. Am I missing something?

Yes, you are correct, the AOB will not be 90 degrees, but that is no problem.

When you enter the AOB 90 degrees, you are looking precisely forward. By closing the TDC panel (thus setting the TDC to automatic mode), the TDC will continue to automatically update AOB according to your looking direction.

So what you really enter in the TDC is that the target AOB will be 90 degrees, when it reaches bearing zero.

@Subcutaneous

You're not missing anything. :DL When you launch a torpedo, AOB is not 90, but when it hits, it will be (that is if you launched at perpendicular course, 0 gyro angle).

This was the part that eluded me...as I was driving to work I suddenly realized I had forgotten about this aspect of the TDC. Once the TDC understands the target track, it's flexible about where the target actually is on that track.

I did come up with this adjustment though: I don't think you actually have to be perpendicular to the track, although I realize it helps the impact detonators. One could use the protractor to calculate the AOB from the target track easily enough, no? Click on the sub, then click on the point where the sub's heading line intersects the track, then anywhere on the track back toward the target. Tweak the resulting angle for your relative position to the target (in front, behind, port, starboard).