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Old 06-02-2016, 07:16 PM   #41
THEBERBSTER
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Default John P Cromwell 45º Attack Method Revised For SHIII

John P Cromwell 45º Attack Method Revised For SHIII.

This method is very useful if you are one of those gamers that likes to get inside the Convoy Lanes.
Firing across the Lanes at 45º rather than the conventional 90º shoot means there is less chance of hitting the wrong Target.

Getting the Target’s speed.

1. Mark an X on the targets bow.
2. Run the 3 minutes and 15 second speed method.
3. Mark an X on the targets bow again.
4. Measure the distance to both X marks i.e. 600 metres = 6 knots.
5. Draw a line through both the X Marks to make a TCL 270ᵒ past the U-boat.
6. Place a 45ᵒ angle on the top of the TCL at a convenient place.
7. Move the U-boat on to 45ᵒ line if possible or parallel to it.
8. Use the Formula below for the attack.

The Formula used showing in the table below is drawn by making a separate diagram on the navigation map.
1. Draw the targets distance covered 600 metres at 270.
2. Using the protractor place the 45angle so it rests on top of the first end.
3. Take the Ruler and draw a line for the torpedo range that you are going to use 1,800 metres.
4. The calculation is Torpedo speed Slow 30 knots x Targets speed 6 knots = 1,800 metres.
5. Place this ruler line on top of the 45protractor angle.
6. Take the ruler again and draw out another line from the opposite end of the 600 metres line.
7. Place one end on the end of the 600 metre line and the other end on top of the 1,800 metres line.
8. With the protractor make an angle on top of the 2 lines =11ᵒ.
9. This 11 is used for setting the AOB.
10. Move the periscope until it shows 0ᵒ = 45ᵒ
11. The firing point is 360ᵒ – 11ᵒ = 349ᵒ on the periscope bearing the Gyro angle will show 000.
12. The AOB always starts at 45ᵒ whether it is Port or Starboard.
13. The AOB setting is 45ᵒ - 11ᵒ = 34ᵒ AOB Starboard in this scenario.

Entering the data in the TDC.
1. In this scenario the target is coming from the left to right (Starboard)
2. The targets speed we know is 6 knots.
3. The torpedo speed is Slow = 30 knots for both G7a and G7e type torpedoes.
4. Enter the data in to the TDC with the periscope bearing on 0ᵒ.
5. Enter the AOB as 45on the 0 periscope bearing.
6. With the TDC closed move the 0 bearing until you see the Gyro angle showing 000.
7. The periscope bearing showing is the firing point.
8. As soon as the periscope is moved the TDC will recalculate the new data automatically.
9. A range to the Target needs to entered in the TDC but has no effect on the outcome.

Torpedo speeds (Multiply the torpedo speed by targets speed)
G7a 44 knots = Fast.
G7a 40 knots = Medium
G7a and G7e 30 knots = Slow

Picture 1 > Formula


Port <-- is the target traveling from Right to Left.
Starboard - -> the target is traveling from Left to Right.
The periscope bearings showing in the Table need to be adjusted until the gyro is showing 000. (JPC is an Imperial method converted here for Metric use.)

Picture 2 > I am situated between Lanes 2 and 3 at 45ᵒ which gives me good protection.
The Convoy’s speed is 6 knots.


Picture 3 > The Target’s Bearing is around 326ᵒ.


Picture 4 > Bearing confirmed in the Periscope view.


Picture 5 > The Range to the Target along the 45ᵒ angle is 1,100 metres.
Notice how all the ships are parallel to each other across the Lanes.
This makes a 90ᵒ shoot very difficult when firing across one lane to the next without hitting the wrong Target.


Picture 6 > The Torpedo track is showing 355ᵒ so needs a small adjustment.


Picture 7 > This is confirmed by the Gyro Angle showing.


Picture 8 > The Periscope Bearing has been adjusted to show a 000 Gyro Angle.


Picture 9 > Perfect Gyro Angle 000 for the shoot.


Picture 10 > All 3 Torpedoes have been on the fired 2 G7e’s and 1 G7a all at a Slow Speed on the Periscopes Bearing as the Target has passed though the Cross Hairs.
As both Torpedoes types have the same Slow Speed I usually both types together when using that speed.
The advantage of the G7e in daylight attacks is that does not leave a wake behind it.


Picture 11 > Notice how all 3 Torpedoes have missed the bigger target with the deeper draft in Lane 3.


Picture 12 > 2 Torpedoes have hit the Target.
The Target has slowed down and it has made the 3rd Torpedo miss.


Picture 13 > Captain’s Log confirming the kill.


Courtesy acknowledgement to Rockin Robbins for giving me this idea.

Last edited by THEBERBSTER; 05-09-2018 at 04:37 PM. Reason: Replaced missing pictures
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