R.A.S Radar Plotter (Nautical)

This interesting British device, contained in its wooden case, was used to plot information from one ship regarding the movement of another vessel.  More can be learned about this device here.  

Instructions for use are printed on a large card contained in the inside of the lid. 

The plotter is in good condition given its age. The plastic rectangular bearing cursor is broken but could likely be carefully repaired with glue, see photos.  The case measures ~ 15.5 in square.