Over at the
Historic Naval Ships Association Board, a gentleman by the name of Mike posted pictures of a Submarine Attack Course Finder (Is-Was) from 1943. The story goes that a family member picked it up for him at a gun show for $5. If you look at his photos, you'll see that it looks like it was made yesterday, so I'm betting that Mike has a very rare find.
Being without an Is-Was myself, but wanting one very badly, I did the next best thing and made my own! Using Mike's high-quality photos, I was able to make what I think is a pretty fair recreation of the main side of his Is-Was, using MS PowerPoint as the drawing program. After creating it in Powerpoint, I converted it to Adobe PDF, and am making the file
available for download here.
Mike said his Is-Was was 7 1/4 inches in diameter, so I made this one that size as well. The first two sheets (The A and B rings) should be printed on heavier card stock, while the second two sheets (The C and Periscope ring) should be printed on transparancies.
I'm halfway done with the second side of the Is-Was, but I'm having problems in figuring out the middle "Bearing in Degrees" ring. The line spacing does not appear to match up with any other standard circular slide rule markings, so I'm not sure if I'll ever be able to complete it. If anyone has any ideas, let me know.
Having played with the Is-Was for a few days now, I think I've figured out how to use it, although there are still a few things about it that bug me. This is what I assume the rings are used for:
A Ring - Represents the submarine, and shows relative bearings
B Ring - Represents the sub's true course/bearing
Periscope Ring - Represents target bearing
C Ring - Represents course and angle on the bow of the enemy vessel
This works for the most part, but there are a few design issues that bother me:
a) I feel that the protrusions on the A Ring are backwards. I always think that the pointy end represents the bow of the sub, and the half-cirlce represents the stern - but if the A Ring is used to represent the sub, then the half-circle is located at the 0-degree marker. This seems counter-intuitive to me.
b) The Periscope Ring should have a more obvious marker to show where AoB is. I know it is 180 degrees from the actual "Periscope" marker, but in the heat of battle, it's easy to forget. I may add a marker to clearly show the AoB.
Despite that, it's going to be a pretty cool toy to use once SH4 arrives. So, please enjoy the Is-Was!
Krunch