Excellent work, Dantenoc. Just for sake of discussion, the lines of position (LOP) not substantiated by celestial observation are known as dead reckoning positions (DR).

You have "nailed" the explanation. :up:

For those who wonder about leaving the Uboat's track to chase target(s)...your other explanations of "How to sink a ship" are just as valid, only now, a lot more challenging. Tnx.