WWII Model 23 Navigators Chronograph

You may have picked up by now that I have an affinity for Hamilton's military watches.  As a former US Navy officer, I guess you could say I view Hamilton's military models as a part of my heritage within "the long blue line".

One of the somewhat ubiquitous Hamilton military models is the Model 23 Chronograph.  It may be common, but it's certainly not inexpensive.  It's a 19 jewel, 16 size stop watch and was paired with the US Navy Model IV octant, as well as a couple of other sextants.  The Model IV octant was an aircraft sextant introduced in 1941.  You can see in the National Geographic advertisement below that the Model 23 was clipped to the side of the Mark IV octant and a trigger pushed the button on the Model 23 to stop and start the stopwatch.

The Smithsonian National Museum of American History has a Mark IV Octant on it's website.  You can clearly see where the Model 23 Chronograph would have been installed on the side.

Navigators would use the octant to measure the position of sun or stars along with the time of day, etc. and calculate the position of the aircraft.

At any given time you can find a number of Model 23's for sale on eBay.  The trick, I'm sure, is to get one that is fully functional and in good shape, as getting replacement parts could be an expensive challenge.

I finally landed a Model 23 for a decent price (under $400).   It needed to be cleaned and serviced but was otherwise in good shape and functional.  The register at the 6 o'clock position is the second hand for the watch.  The large second hand is the stopwatch seconds and the register at 12 o'clock is the minutes for the stopwatch.  So this chronograph records up to 30 minutes.  When the stopwatch's second hand makes a full revolution, the minute hand indexes one mark.

You push the button on the pendant to start the watch or stop the watch and pushing it a third time will reset the hands to zero.

The case back of the Model 23 watches are engraved with the specific contract, etc. for which it was originally purchased.  This one appears to have been for the Air Force and the serial number on the movement appears to be post-1944 although dating these movements is tricky.  Most online tools based on serial numbers are inaccurate.   This case back also has what I assume was an air crewman's name.

Chronographs are quite complicated.  If you're looking forward to seeing me take this one apart, I'm sorry to disappoint you.  I don't have the confidence yet to tackle a chronograph so I sent it out to a pro to handle.

Chronographs have basically two levels.  What you see below is the chrono-level built on top of the regular watch works.  So you don't see the ratchet wheel for the mainspring, etc. that you would normally see on a 16 size pocket watch.  If you took the chrono-level off, you'd see the pocket watch underneath.

In this shot, looking over the balance and at the the third wheel, you can see it has an extra-long upper pivot with a wheel attached to it.  The bridge that says "Model 23" supports the pivot.

The extra wheel on the third wheel pivot is always turning when the watch is running.  It drives the little gold wheel to the upper left of it.  So the two wheels are always rotating.

When you engage the stop watch, the upper wheel moves over to the central sweep second wheel, as shown below.  Now the watch is powering the chronograph function.  As the sweep second wheel turns, it moves all of the other functions until the watch is stopped and reset.  Complicated, huh?

The Model 23 is really a pretty movement, in my opinion.  I've even seen these movements installed in a wrist watch case.  A 16 Size makes a very large wrist watch but if that gives new life to these extraordinary watches, so be it.  They deserve to be enjoyed.

For me, I'll keep this one in it's original form.

M is for Mystery

I recently learned that the M-series of watches were produced from 1961 through 1967.  It seemed like once I learned that I found a couple of new models.  Unfortunately I don't have the catalogs for the years other than 1964 so I can't really identify the watches.

One apparent common theme to the manual winding M-series with RGP cases I have found is they each have very similar case designs although they're not all the same size.

Compare for your self...  here's one from June 2014.

And this one from earlier in February this year.

Now I have another one.  As received it was in obvious need of a new crystal.  Sometimes crystals will craze like this over time if they are compressed too tightly during installation.

Although the physical sizes vary, the mystery models that I have come across all come in a one-piece 10K RGP case with very similar case designs elements... flat back, thin lugs, etc.

Without the crystal in the way, I can see that there is some glue residue around the outside of the dial from someone sloppily gluing the crystal on.

The dial design is very interesting.  It's got raised gold numerals and the inset hour markers are silver.  The chapter ring going around the perimeter is also silver.  This dial looks a lot like several models in the Electric Nautilus line from around 1963.

Behind the dial is a 17 jewel 686 movement.  I've seen these mystery models with 686 movements as well as 671 grades.

The case back is clearly marked Hamilton W. Co. Lancaster PA and the case maker is D&A.  That's been the case (pardon the pun) with the other models too.

Everything is cleaned and ready for reassembly.  I was able to get the glue off most of the dial except for on the chapter ring near the 2 marker.

I like the 686 movement - it's very easy to regulate once you get it running.

How's that for performance?

The dial and hand get installed and the movement goes back into the case.  You can still see some glue residue on the dial but that's the breaks, I'm afraid.  You can't be sloppy when it comes to watches.

The last thing to go on is a properly fitting 30.6mm high dome crystal.

A lizard strap completes the overhaul and you can clearly see what a huge difference a new crystal makes to a tired old watch.  The crystal hides most of the glue residue that was left on the dial.  This mystery model looks great to my eye.

A Tale of Two Watches

I recently picked up a project watch that I thought looked familiar.

It came in a one-piece rolled gold plated case.

When I went to identify it I thought it looked a lot like a 1964 Sea Haven.  But I was puzzled by the thinness of the bezel on my watch and the catalog says the Sea Haven has a stainless steel back.

Weird.

Then I remembered that I have a Sea Haven in my collection.  I rarely wear it because it has an expansion bracelet.  It looks exactly like the catalog (well, not the bracelet of course).  So something was up with my project watch.

Although the Sea Haven has a stainless steel back, it's still a one piece case and it cannot be separated from the RGP bezel.

Without the crystals in place you can see the dials are very similar.  They certainly have the same pattern but the finish on the Sea Haven is a radial finish while the other watch has a plain white finish.

The cases are both marked Hamilton Watch Co.  The Sea Haven on the left is quite different from the project watch.  The project watch is very similar to M-series watches I have seen though.  So I suspect the project watch is a post-1964 M-series watch... but I don't have any catalogs to confirm that hypothesis.

Both watches have the same size dials and both run a 17 jewel 686 movement.  Oddly enough, the project watch movement is a lot cleaner-looking than the Sea Haven.

The back of the project watch's dial has some numbers scratched in, specifically 1972... I wonder if the dial was refinished back then and lost it's original radial finish?

Both watches are completely disassembled, cleaned and dried before being reassembled with fresh lubrication.

The Sea Haven's movement is the first to be reassembled.  Next stop is the timer.

A little tweaking to the regulator brings the beat rate right in line.  The amplitude and the beat error look great too.

Now it's the project watch's turn to be reassembled.  This one is running nicely too.

This one started out running a little fast but a couple of tweaks slowed it back down.

I decided to put the expansion bracelet onto the project watch.  A new GS PHD crystal and a fresh crown complete the restoration.  It doesn't look too bad.

The Sea Haven gets a new black lizard strap.  With all things being equal, the original radial-finished dial makes the Sea Haven a much sharper looking watch.