Dunno if anyone noticed this but in 1941 US Navy Maneuvering Board Manual, there's a bearing only method in case XI called "TO DETERMINE COURSE, SPEED, AND RELATIVE POSITION OF A TARGET BY BEARINGS ALONE".
(
https://ia800203.us.archive.org/22/i...oard00unit.pdf)
And also the same method located in 2001 Maneuvering Board Manual, Chapter 6, example 25. (
https://www.sliderulemuseum.com/Manu...oardManual.pdf)
Thinking of giving it a try?