The courses and speeds of the two ships/aircraft/missiles/etc are irrelevant. As long as they are CBDR they will collide at some point in time.
The math is simple and even simpler visually when using a Polar Geographic Plot such as a maneuvering board. It can be done directly on the screen of a radar repeater using a grease pencil.
Being good at maneuvering board was one of the things that cemented my position as CIC officer and earned me the respect of the men. I could beat any of them, except the Chief, during MB drills. That included the OS1 who made Chief a year later. I helped that the Weapons Officer, whom I was paired with for bridge watches when I was JOOD, taught me how to do the approximations in my head. Once you can visualize what the final answer should look like it is even easier to get the exact answer on the MB.
SpyNavy
Garde la Foi, mes amis! Nous nous sommes les sauveurs de la République! Maintenant et Toujours!
(Keep the Faith, my friends! We are the saviors of the Republic! Now and Forever!)
LonePalm, le Républicain du verre cassé (The Broken Glass Republican)
