Error of my ways with OLC GUI (help)

[GoldenRivet]

I have recently downloaded the GWX2 version of the OLC GUI with course finder and attack disk etc etc.and i love the immersion this mod provides.

Though im still averaging about 30K tons per patrol with manual targeting, My success for scoring torpedo hits with this mod however is about 50/50.

In almost every solution i prepare, the torpedo tracks aft of the target. my immediate assumtion is that im calculating speed incorrectly.

Ill post what im doing step by step and perhaps someone can show me the error of my ways.

1. Identify the ship
2. Calculate the target speed. I do this by the following method: Im moving at 1kt or less while not turning, when the bow crosses the vertical cross hair in the scope i start time and when the stern crosses the vertical cross hair on the scope i stop time. Length of the ship as taken from the recognition manual divided by time in seconds multiplied time 1.94 = speed in knots.
3. Input speed into the TDC
4. Lock scope to target
5. Open recognition manual by clicking target name
6. count vertical marks to the tallest mast
7. locate vertical marks on the marks ring and rotate so that it aligns with 90 degrees.
8. locate the mast height on the outer ring and read range directly across from it on the mid ring
9. input range to TDC
10. click on the mast height value and rotate it to the length value.
11. count horizontal marks along the ships bow
12. locate the horizontal marks value on the marks ring and read AOB directly across from it.
13. Input AOB into TDC /Open tube(s)
14. Auto Update the TDC
15. Fire

in nearly every case i fire a spread of two torpedoes... in nearly every case one fish strikes the aft 1/3 of the ship while the 2nd fish passes behind the ship.

the bearing must be right as the scope is locked... the range is always fairly close... i think i am either computing AOB or speed incorrectly. sometimes my horizontal marks value aligns beyond 90 degree AOB on the Range/AOB finder even though the AOB is obviously much less than 90 degrees.

any help would be great