[CapnScurvy]

If your playing the stock game, all stadimeter readings are taken with the second imposed image having the ships waterline placed on the targets tallest mast top. Don't forget to ID the target in the Recognition Manual, and mouse click the "checkmark" box in the upper right of the page. This sends the Mast Height: to the TDC/Position Keeper. You know you've sent the proper ID and Height when the targets name appears at the top of the PK. Mast Height is measured from waterline to top of the mast.

The stadimeter is very sensitive, just misplacing the waterline off a couple of pixel widths can throw off the range by several 100 yards. Not to mention the Height figures aren't very accurate. For instance the original stock Jap Hiryu CV had a Mast Height of 20 meters. To get an accurate range reading the Mast Height should have been 37 meters tall. No matter how you measure it with the figure off that much, you'll only get a range reading of about half the distance it should be!!

I've created several mods that try to give you a better estimate of range from the stadimeter by accurately measuring the Height: distance and putting them into the Recognition Manual. Ship Centered, Accuracy Fix (SCAF) was an early mod that corrected ship heights. It also allowed for other places to be used (rather than the mast top) like a ships funnel, CV's flight deck, of the top of the bridge (superstructure). The Recognition Manual pages are marked with a red pencil to show where you set the waterline mark. Optical Targeting Correction is my latest mod that does the same thing as SCAF but yet more accurate. The periscope is scaled to accurately portray the correct Field of View allowing the lens hash marks (Telemeter Divisions) to finally be used in measuring a target's height. Something the game missed badly. For the most part the stock Telemeter Divisions were worthless in measuring anything accurately, worse than the stadimeter!

I wouldn't worry about jumping into modding your game right now since your just learning the ropes. But I highly recommend using OTC if you're going to try manual targeting. Without it, you're just shooting a pistol that misses the target badly, unless you're so close you can't miss.