The board is actually pretty easy once you get the hang of it. It is called a "Mo Board" short for manuvering board. We used them all the time in the Navy to calculate CPA's (closest points of approach), winds (true and actual) and speed of the target. The key is the scale at the bottom where the "X" is marked across on the speed and time lines. All the marks on the board are marks of estimated target position. Obviously with own ships position in the center. Real fun keeping track when you start manuvering and changing speeds. The Navy STILL uses these as a backup to all the new fandangled computers. It is a requirement to use the mo board to qualify Officer of the Deck. Computers are great but nice to have the back up when it goes belly up due to damage of some type.
