[Rockin Robbins]

Aside from the 19º typo which you meant 9º lead angle with boom happening at bearing 19º, and the fact that both lead angles will be slightly different from 9º because they are not set for impact exactly at the zero bearing you have it exactly right! That is what make Dick O'Kane and John P Cromwell very resilient and resistant to human error. You can quickly retarget on the fly as coffee singes your gonads and you spend a bit of time cussing at the yeoman.

Perfectly explained!