I need clarification on "window depth"

Regarding the IRCWCC rules on construction:

Maximum 15% impenetrable, including your maximum 2" bow, maximum 1" stern, and all ribs (no problem, easy)

Maximum 3/8" ribs (no problem, most are using 1/4" anyways)

Main deck(s) shall be no more than 3/8" thick (easy)

Part 6, however, causes problems for me:

6. Impenetrable material may be used as hull skin on a ship’s bottom,
but it shall end at least 1" below the waterline,
or more than 45 degrees down the turn of the bilge (see Diagram B).

There's just no smeggin' way to cut some of the windows a full 1" below the waterline on some ships, specifically the current inherited one I'm re-sheeting (HMS Dreadnaught). Some of the stern windows are less that 2" in total height because if you cut lower you are effectively cutting off the stern keel of the ship and cutting off the rudder and propeller mounts.

Is there some form of accepted "common sense" or guideline regarding window depth below the waterline on shallow vessels like some cruisers and most, or all, destroyers? I assume it's something along the line of "do the best you can", but what's the generally accepted ruling for window depth?

I mean, I'm sure not cutting into my impenetrable keel where I mount all my hardware. Could someone with more experience please enlighten me on how shallow hull windows, not a full 1" below waterline, are handled? Hopefully common sense rules.

 

Yep. 45 degree rule is for the areas where you can't use the 1" rule. Of course, if you want, you can use the 45 degree rule for the entire hull

 

Ah, read that 2-3 times but never understood it. Thanks for explaining it.

 

Here is some pictoral help from the Western Warship Combat Club. They use the 60 Degree rule, but you get the idea: