Periscope Range???
 

Just a real quick question about using the periscope for ranging? You take the picture. OK I got that. You then scroll the right side to the highest mast. Question is in the crosshairs do you put the horizontal line on the keel of the target and measure from that or do you make sure that horizontal bar is on the horizion itself and measure from that? Thanks for any feedback.

You put the horizontal line in the periscope on the waterline. You do that where the water meets the ships hull. After you take the photograph in the periscope, go to the stadimeter and use the side containing the highest mast and line that up with the waterline.

Highest structure tends to be more reliable than highest mast, despite information in the manual.