Stadimeter

[btaft]

I a starting to make the transition to full manual tracking but have kept map updates on to check my results for the time being. I have found my ranges to be off by a decent amount (typically short) when using the stadimeter. My understandng is that I ID the target, check the box, line the cross hair to the water line of the first image and then bring the second image's water line to the top of the mast of the first image to obtain the angle. Even in calm water I seem to get shorter ranges. I am not looking to complain, just looking to see if I got it right. Any help is appreciated