Submarine Attack Course Finder (a.k.a. Is-Was / Banjo)

[Captain Krunch]

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

[fire-fox]

Very nice find! ill D/L it when i get home from work, any idea if there is a rivers side to the real one and if there is are there any plans for you/any one else to make it?

EDIT: sorry just read the secound half of your post and feal prity thike as you already answerd this Q.

Very Cool Krunch - thnx a mill for the work

As for materials - tranperencys wont cut it as you wrote on HNSA (can't answer there as i have no account), but if you make the layer in transparent paper and then laminate it with the thikest lamination you can get (paperstors usualy can do that for you pretty cheep) then i think that will work.

Would it be hard for you to make a version where all the pages (wheels) are all white? I would like to make the colorisation by the use of colored paper (off white etc.)

Hmmm in construction it pretty much resembles a Nasmith Director witch was allso a Target Course Finder.

[Captain Krunch]

I agree that transparencies are not the best solution, but at least they're readily available to most people. My mock-up was made out of card stock and transparencies, and it seems to be holding up fairly well. But I like your idea of using clear lamination to give it strength; that's a lot simpler than what I was going to do (Which was make decals and put them on clear styrene sheets).

It's no problem to make a complete black and white one; it'll be a day or two at most.

I used the lamination method on all the transparent of Kim's Tools some time back, and it holds out really good, and they are pretty stiff as well.

Im not in a hurry here, so whenever you see fit - im just glad you take the time to make it

[Rykaird]

Originally Posted by Captain Krunch

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.

I have seriously got to go to my first gun show. I thought they only had guns - not cool historical sub stuff.

[Captain Krunch]

I've posted an all B&W version of the Is-Was here. Let me know if there are any problems with it.

Originally Posted by Captain Krunch

I've posted an all B&W version of the Is-Was here. Let me know if there are any problems with it.

File was deleted.
Reason: Deleted by uploader.

Thats what pops up when i click the link 8th march 2200 GMT

BUHUUHUUUuuuuuuuu

[Captain Krunch]

Wow, that's weird, sorry about that. Try this link; it seems to be working for me:

B&W Is-Was

That one worked like a charm - much appreciated

[Hitman]

'm halfway done with the second side of the Is-Was

Has that reverse side been finished yet? Looking forward to printing it

[sqk7744]

Me too, Brilliant printable version may I say, it's great fun and really adds to the immersion! I wonder if there is a store/site that has overstock issue? Sportys.com pilot shop has original E6B's from the 40's, can any skips' out there suggest some Naval ones?

Take a bow Captain Krunch!

[Hitman]

I have already built mine thanks to your template, and it looks and works AWESOME. Finding the AOB has never been that easy since now I can put the wheel HORIZONTALLY in front of me (Instead of vertically, as the monitor display of the PC we are used to) and thus it is much easier to compare with the enemy vessel you are seeing -which despite being also rendered vertically, has "3D" depth-.

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.

He he I found out why the A scale is reverse pretty quick :p It is meant to be read from the PERISCOPE layer (The transparent one with marks) and not from the own ship overlay of the A disk.

Example: A target is 45º to the right of your bow, and has an AOB of 60º port. You are heading 200º right now. Here's how to set up the wheel:

1.- Move the B ring (True course) until its 200º mark is at the bow of your own ship silhouette in ring A (Matching the 180º mark in the A ring)

2.- Move the Periscope transparent layer to the 45º mark of the A ring. (Here's the reason why it is reversed! To move your scope "right" means in fact moving in the opposite direction the lower part of that wheel, so that the upper shows the target with the correct AOB side)

3.- Last, set the estimated AOB of your target (60º port) in the B ring.

Result: Your target's true course is 105º, as you can now read in the B ring (True course ring)

[Meridian]

Looking forward to printing and making one of these up, nice job.

I assume Parts "P" & "C" are printed on transparent media?