I'm following the Wreck 'em with no rec manual tutorial

Got a decent grasp of everything but, in video 4 I'm hoping to get a better handle on how he changes his 3500 meter calculation from the disc to a 2500 meter estimate after executing the 90 degree to port turn, when going into a perpendicular course with the target convoy.

Hamacher is kind of using the mast height at this stage to judge the 2500 meter mark as said in the video but, I'm trying to do it without mast height in this step.

Edit: I suppose I can figure that using the attack disc, I know Hamacher travels about 185m @3 knots during the 90 degree turn. I can multiply that by 4 and figure the radius of that circle and that probably equals both the Transfer and the Advance, so probably 117 meters for both during the 2 minutes and 345 meters for the cargo ships. Not a neat equation to do while sailing though. Will edit more with any updates as I work this out.

I think the answer is to calculate Transfer and Advance during the turn. It looks like it takes Hamacher 2 minutes to execute the turn. Over which time the target freighters would travel some x meters. If I could work out Transfer and Advance of the sub @ 3 knots during those 2 minutes I'd know the distance without using mast height.

http://shipofficer.com/so/wp-content...ng-Circles.pdf
I found this article interesting but, does anyone know a way to do transfer and advance calculations off the attack disc, or something like it?