Need help with RAOBF calculation

[Lymark]

I've recently started playing SH3 GWX for the first time(Yeah i know, only played SH4/5 before), been practicing manual TDC with the stationary tramp steamer in torpedo exam using RAOBF, and I've just realized that my range/AOB calculation has been very inaccurate even though the method is correct. I'll describe my issue with the following screenshot:

Tramp Steamer: ~800m, AOB:~36 from torpedo exam


To my understanding, getting range by multiplying mast height x2 is the nom here in SH3. However, in my case, that would result in the range being doubled. Even weirder, If I were to drag the 800m mark to the ship's length(78.5m) then read off the AOB based on center to bow length tick(7 ticks), AOB would be ~20 degrees off. Therefore, I now have to multiply the mast height after getting my range, instead of dragging the calculated range right away.

Not really a big deal, but I have been pulling my hair wondering why my math is different than everyone else. It also confuses me because I feel like I'm not doing it right.

I'm using 'ARB WideGui 1920x1080'(an improved version of Ahnenerbe's), and the only mod I think that might have an effect on this are both MFM and MFM's displacement correction mod.

Any help would be appreciated! Thank you!