How to do a spread attack?

[DavyJonesFootlocker]

Never did try this. I had a smart medium merchant giving me hell zig-zagging all the way at 5 knts . I was behind him and sent two torps and all missed. Thinking of next time to do a spread attack so if he moves to port and then to starboard I can at least hit him with one.

[Quillan]

In that circumstance, I wouldn't waste torpedoes. My preferred method for attacking those guys is to ignore the zig zag. They're just going back and forth a couple of hundred yards to either side, but maintaining the same overall course and going slower because of it. I try to plot out the points where the target reaches the edge and turns back the other direction. I draw lines down each side's point, and then I treat his actual course as a line down the center of the two I just drew. I figure out his effective speed based on how long it takes to go from point to point on the same side of his course, and fire based on that. It works. I don't have anything here at work to post graphics with, though, so I can't give you diagrams.

[DavyJonesFootlocker]

Thanks. I'll try that method later.

[Buffalo9]

If I have the time I plot their base course then watch and plot their zig pattern.
If it's scripted in the game there should be a set pattern to their maneuvering. One you have their time on course it's then just a matter of you getting into position within the time and ranging constaints.
The easiest and safest way is to use radar to plot their base course and zigzag course, it's a good standoff method and allows you more time to plot any deviations.

[Capt. Shark Bait]

been wondering about this too. target moving from left to right, is the dial set to what's on the upper half, or lower? the reverse would be true for R to L.:-?

[Ducimus]

The key problem with firing a fan shot at a zig zaggin target that knows your there, is getting a firing solution along his base or mean course. (edit: assuming your going for an up the skirt, or down the throat shot) If your a PK addict like i am, this becomes rather difficult at times.

[Captain Vlad]

Mad Zig-Zagging usually results in me doing the '600 yards, no TDC' thing.

[Mav87th]

I took out a KASAGISAN MARU last night that made continous rudder zigzags (full deflection one way into full deflection the other way). I had originaly set up for a 90 AoB shot but his longest straight time were on the Zig's or Zag's.

So i plotted his zig and zags, witch did not take too long as i made a plot every 20 seconds over 3 min's and had a fine row of small circles (i use the tool that makes a circle to make my plots, small 50ft circles when its not a 3 min plot and large 200 ft. circles when it is done in a 3rd min (3,6,9,12 etc.)

ANYWAY
the short plot of his Zig Zag enabled me to turn my boat 25 deg. to the right away from the original 90 deg AoB to a new 90 deg AoB lineup on the Zag leg.

I had timed his time in the Zag to 30 sec's so i knew i had to shoot fast as he got into the Zag. Therefor i had prepared AoB on the dial on 88 deg, Speed was dialed in on 6 kts. Doors open and draft sat. Torpedo speed sat on fast.

Mouse rested uppon the stadimeter and as he settled on the Zag i took a stadimeter reading for range and sent it to the TDC - then unlocked him and had his rear mast ligned up on the crosshair and sent range again to update the new aimpoint - Fire one....´

Moved the crosshar to his bow and had him sail through it untill the front of the superstructure, then sent range again..again updating the new aimpoint. Fire two...


I like to fire my spreads from aft to fore. I have been doing that sinced i read O'Kanes book, but i cant remember the reason form his recomendation of why to do that - the book is lent to a buddy so i cant look it up right now.

[joegrundman]

From the greatest source on torpedo attacks available:

the submarine torpedo fire control manual 1950 (this thing should be hosted by SUBSIM and made to be required reading with an exam for all members before being allowed to graduate beyond Bilge Rat)

http://www.hnsa.org/doc/attack/index.htm

and particularly the chapter on spreads

http://www.hnsa.org/doc/attack/index.htm#chap06

Anyway one of the many marvellous things it talks about is computed spread, based on a simple formula (which like many others i have taped onto my lamp for easy reference), and this can be calculated long in advance in a spare few seconds while tracking the target and once you have a good idea at what the setup will be when you fire.

No. degrees in total spread = (target length in feet/100)x(%coverage)x(2000/torpedo run in yards) x Sin AOB at moment of impact.

This formula may look complex for the not so mathematically inclined, but do you think 18 year-old Billy Bob Johnson from Alabama had a phd in math when he got assigned to the tracking party? All it takes is a llittle patience.

Target length is easy.

Big merchants can be apporximated to 500 feet
Medium merchants can be approximated to 400 feet
small merchants and destroyers can ne approximated to 250 feet

So divided by 100 you have 5, 4 and 2.5 respectively

Coverage is also easy, this is the number of target lengths you wish the spread to cover. Let's say it's long range and you are not to sure about the speed solution so you choose 2 target lengts. so that's 2.

torpedo run is ideally 1000 yards, so 2000/1000 = 2

and sin AOB

well you usually want to hit the target moreorless side on, don't you? So sin AOB =1. If the angle is 30, then sin AOB = 0.5.

You don't need to be exact in this.

So my spread for a large merchant at 2000 yards with a 90 AOB and a 2x target coverage

= (500/100) x 2 x (2000/2000) x 1
= 5x2x1x1=10 degrees of TOTAL Spread.

(obviously some among you will already have appreciated taht with a 200% coverage you mustn't use only 2 torpedoes otherwise your target may pass between them)

that's it