1955-ish US Navy Periscope Camera Watch with 735A movement

Probably one of the most obscure Hamilton military watches is the Submarine Periscope Camera Watch, part number 39360-2-01.  I couldn't find much about it online, but there are quite a few forum posts about it.  The photos below are from a NAWCC discussion.

What makes the timepiece unique, other than the application it's used for, is the movement that's powering it.  It's a Hamilton 735A.

The Hamilton 735 is the 18 jewel, 8/0 sized sweep second caliber that Hamilton introduced in 1955 to replace the previously used 748 movement.  The primary difference is the introduction of shock jewels to protect the balance on the 735.  Otherwise the calibers share the majority of parts.

So what is the 735A?   Another NAWCC forum post explained there are actually three versions of the 735.  The basic 735 (part number 44011), the 735A (part number 44012), and there's even a 735S (part number 44013), which has a hack feature.  What makes the 735A unique is the specifications that the pallet stones and impulse jewel on the balance were secured with Hysol 250L, the train jewels, train pivots and pallet stones were treated with a special anti-spread compound, and the pallet pivots and lower fourth pivot were not lubricated.  

So there's nothing you'll physically observe that differentiates a 735A, other than perhaps the lack of shellac holding the pallet stones in place.

I recently was contacted by someone who was having a problem with theirs and it was the perfect opportunity to see for myself.

As you can observe in the photos above, the periscope camera watch was presented in a hardened aluminum case with a waterproof crown, similar to the USN BUSHIPS Canteen.  The dial is very similar too but it's not luminous and the watch is not powered by a 987S movement.

My project watch movement came presented in an aftermarket case that has military styling but it's not a military case.  This watch was dropped, hard, and the second hand came off.  It's not running and when I try to set the time the hands don't move as expected.  So something is definitely going on.

As I said, the case looks military but it's a generic aftermarket case.  A case wrench is needed to open it up.

Inside the case is the 735A movement secured by a generic movement ring.  Once I loosen the set lever screw and pull the stem, the assembly will come out the back opening.



The dial is very worn.  I wouldn't be surprised if it was refinished but the luster of the paint is unusual and very chalkboard-like.  The white flecks are actually missing paint chips, not dust or debris.

I do not see the seconds hand pivot sticking out of the center of the movement.  I also don't see any dial feet screws.

The lack of dial foot screws tells me the dial is likely held on by dial dots, or little double-sided adhesive stickers. 

After carefully prying off the dial, I can see the back of the dial is totally flat, there are no dial feet.  I can't even tell where there might have been dial feet before.  The back of the dial is all scratched up.

Sure enough, you can see the remnants of the dial stickers on the surface of the main plate.

The shaft of the center wheel is broken off inside the cannon pinion.  You might be able to see it's still sticking out.  That's why I couldn't set the time, the cannon pinion and the hour wheel were just floating under the dial.

I can see the long pivot of the 4th wheel sticking out of the movement.  I couldn't see it before simply because the cannon pinion was blocking it.

I'll replace the center wheel and hopefully the movement will be good to go again.

I used a small broach to push the remnants of the broken center wheel out of the cannon pinion.

Everything has been cleaned and I replaced the crystal with a fresh one.  Now it's ready to be reassembled.

It doesn't look like it but the movement is ticking away with a nice motion.  I don't have the compounds used originally to lubricate the movement so I just lubricated it like I'd do with any other 735 movement.

It's running nicely, just a little slow.  A tweak or two to the regulator will bring it right in line.

A tweak here, a tweak there, and it's now running just a little fast - that's fine for now.  It will probably settle down after a while.

I'm going to need some fresh dial dots to mount the dial again.  You can see why they're called dots.  The little tan discs are actually covers for the sticky part.  You lift them off, stick them to the main plate and then pull the tan cover off to reveal the other sticky side.

Four ought to do the trick.  Now I just need to center the dial in the right orientation and press it on.

With a fresh crystal, this watch now looks a lot better.  The dial is what it is, there's not much to do about it other than find a better example or custom refinish a dial from a Secometer B.  That model used a 748 so the dial feet would match perfectly.