Alfonso Faustino: Seiko Tortoise Prospex SRPG13 Field Watch & Hamilton Khaki Automatic A-11-style Field Watch

As mentioned, I recently took possession and custody of a Seiko Tortoise Prospex SRPG13 Field Watch (wrist timepiece); and, I really dig this awesome wrist timepiece.

It is definitely an added playa to my small wrist timepiece collection!

An acquaintance asked me, hey, I’m interested in picking up the Hamilton Khaki Automatic [A-11] [Retro-style]; I saw in your BLOG that you have one — should I purchase it?

Had he asked me this question prior to my acquisition of my Seiko Tortoise Prospex SRPG13, hereinafter, Seiko Tortoise, I would have said, Yes!

Now that I have my Seiko Tortoise, I say, Yes, but wait — there’s more!

The 42mm A-11 Retro-style Hamilton Khaki Automatic, hereinafter, Hamilton Khaki, has been in my collection ~three years now, and I dig this wrist timepiece.

The selling features of the Hamilton Khaki wrist timepiece, for me, are the following:

  • A-11 Retro-style design — specific to A-11 WWII wrist timepieces
  • Simple functions: Time & Date
  • Sapphire Crystal
  • Water Resistant to 100 Metres
  • Glow in the dark Numbers and hands
  • Durable
  • Hack
  • Accurate Swiss Movement: H-10 Movement
  • Hamilton’s Historical Legacy during World War II

Feature(s) I wish the Hamilton Khaki had:

Screw-down crown.

I realize that a screw-down crown, during WWII could create an extra step in accessing the Hack feature before and after synchronizing a set time during a mission within a team; but, the USN Frogman in WWII had an A-11 wrist timepiece with a screw-down device in the USN BUSHIPS Canteen; and, they had to synchronize with each other to blow up German sea vessels and submarines in the water and out of the water.

I also understand the Hamilton Khaki, as well as other manufacturers of present-day A-11-style wrist timepieces, want to keep to the original design of the authentic A-11 WWII wrist timepieces, and a screw-down crown was not present in that era except for the WWII USN Frogman and their Canteen wrist timepieces.

Notwithstanding the interest to keeping the authenticity of A-11s, let’s also realize these are reissued items in our present-day, which have been materially modified to meet the market’s interest; so, why not include a screw-down crown?

The main selling feature for the Hamilton Khaki is the A-11 face, which satisfies the requirement of a collector wanting an A-11 timepiece in their collection.

A strong following of watch-enthusiasts exist for the A-11 WWII looking wrist timepiece faces, and that would be the main selling feature the Hamilton Khaki. The other aforementioned features are definitely selling points that seal-the-deal for purchasing THIS Hamilton A-11-style wrist timepiece; because, other A-11-style Field wrist time-pieces made by OTHER manufacturers, including Seiko, do not have the aforementioned features that Hamilton throws into the Hamilton Khaki.

All these goodies and the A-11-style face goes for around $479 for the Hamilton Khaki Automatic.

I was in Disneyland, Anaheim, CA, July 2021, and I wore my Hamilton Khaki. While we were rushing to a Star Wars line, I swung around a metal barrier a bit too close and fast, and I BANGED the sapphire crystal face of my Hamilton Khaki, and I can still hear the sound and feeling of my wrist as I write this BLOG section.

Man, it was a terrible sound. I immediately looked at my Hamilton Khaki, and to my surprise, not a single mark — the sapphire crystal was perfect. No dent nor scratch on the Hamilton Khaki case — it still looks brand new, holds accurate time, and still water resistant — believe me, that BANG had me believing I damaged my Hamilton Khaki, but I was wrong — everything, to date, is fine.

My Hamilton Khaki lacks only one feature that I always think about whenever I take it in the ocean, shower, or bath…no SCREW-DOWN CROWN!

To date, in all the water dunks in salt-water and fresh water, my Hamilton Khaki has not leaked.

Yes, it’s more of my own psychological issue with me, en re no screw-down crown; because, my Hamilton Khaki has maintained its water seal during my possession during water activities.

So, I’m fortunate to have BOTH the Hamilton Khaki and my new addition to my wrist timepiece collection: Seiko Tortoise; hence, I’m able to create this BLOG and present my thoughts about these two wonderful wrist timepieces.

The Seiko Tortoise is not an A-11 military-style wrist timepiece like the Hamilton Khaki; and, it will not pass to fill in the spot of an A-11-style wrist timepiece if that is your requirement for your collection; BUT, the Seiko Tortoise is a field wrist timepiece, designed for land operations; and, this category is shared between the Seiko Tortoise and the Hamilton Khaki. Their land-based qualities are the area of focus in my comparison between the two wrist timepieces.

Let me start with the stuff I really dig about my Seiko Tortoise:

  • Design and color availabilities: Rose Gold, Black, Navy Blue, and Green
  • Nicely crafted metal case number markers
  • Bright glow-in-the-dark markers, hands, and second-hand
  • Hack
  • Good heft and weight — these two elements make me feel like my money went into a quality wrist time-piece
  • Accurate Japanese Movement: 4R35
  • Sapphire Crystal
  • Screw-down crown
  • Navigation Compass Bezel Marker to manually locate a North heading, which can also be used to measure lapsed time like a Diver’s bezel
  • Ground-to-Air Communications Legend
  • 200 Metre Water Resistant Rating
  • Date Complication located between the 4 and 5 markers
  • Exterior Lug-spring holes
  • Beautifully-designed casing: Turtle lineage
  • Seiko’s historical legacy
  • Seiko builds their wrist timepieces all in-house; they don’t use vendors to farm out parts. Seiko’s wrist timepieces are all created under one roof: face, casing, movement, time markers/numbers, hands, and bracelet — not so for Hamilton, which is owned by Swatch.

Feature(s) I wish the Seiko Tortoise had:

  • The Air-to-Ground Legend doesn’t seem to engraved nor etched into the rear casing or the Seiko Tortoise — I could be wrong; but, if my assessment is correct, then I’m concerned the data will wear off.
  • I wish Seiko added clicks to the compass bezel. It’s a bi-directional bezel that is snug and moves without clicks. I like the clicks for tactile reasons, but the clicks makes it harder for the bezel to move during movements, such as reaching into my pocket. When I reach into my pocket, the bezel moves; I also wear my wrist timepieces to bed, and I wake up the next morning to see that, while in my sleep movements, the Seiko Tortoise bezel moved.
  • In my opinion, Prospex, should be ProSpex or Pro Spex. It wasn’t until I learned that Seiko has a line of Pro Specification (Prospex) wrist timepieces; hence, Prospex, which is two words, Pro Specification(s), should be demarcated to show that Prospex is two words. At its present marketing copy, it is one word, and I keep thinking Prospect.

Let’s visually compare the Hamilton Khaki and Seiko Tortoise.

I’m a huge fan of Seiko’s Turtle casing, which is passed in to the casing of the Seiko SRPG13, which has been colloquially called, The Tortoise, to follow the Turtle naming theme. The Tortoise case is super comfortable on my wrist, and the Tortoise casing is visually appealing to me. It looks compact, balanced, and feels good in my hands. I like that the design is smooth and has no sharp edges like the Hamilton Khaki casing. I also like the lug shoulders don’t protrude out like the Hamilton Khaki.
Check out the time on both timepieces. The Hamilton Khaki’s time was set about two months ago; and, the Seiko Tortoise’s time was just set at the time of the photo-shoot, which is 7-April-2022. Hamilton Khaki, in two months, is only ~1 minute faster, and has been holding that +1 minute — that’s the Swiss H-10 Movement — pretty damn good for a wrist timepiece under $1000.

If I had only $600, which one would I purchase if A-11 style wasn’t part of my requirement for my collection?

Seiko Tortoise


  • Screw-down crown
  • Unique color
  • 200 Metres Water Resistant Rating
  • Field Compass Bezel to manually locate a North heading, and I use the bezel like a diver’s wrist timepiece to measure lapsed time
  • Sapphire Crystal
  • Better time markers
  • Heft and Weight
  • Beautiful casing
  • Less expensive with more features than the Hamilton Khaki

In my opinion, I get more goodies for my money with the Seiko Tortoise if I ain’t interested in adding an A-11-style wrist timepiece to my collection. The Seiko Tortoise is less expensive than the Hamilton Khaki, and I get more features.

If I had $1200, would you get both?


I like the A-11 Retro-style WWII look of the Hamilton Khaki; and, it is one of my requirements for my collection.

If you’re interested only in a FIELD wrist timepiece, then you might consider the Seiko Tortoise over the Hamilton Khaki; because, you are getting a field tool: Compass Bezel, which you can also use to measure lapsed time like a diver’s wrist timepiece bezel, Air-to-Ground Communications Legend, and Screw-down Crown to ease your psychological concerns that the crown will NOT pop open in any condition — in and out of water. The price is less than the Hamilton Khaki, and you get more features.

If you’re interested in a decorative A-11 Retro-style field wrist timepiece to satisfy your WWII nostalgia and add to your collection; then the Hamilton Khaki IS the wrist timepiece fit for you.

Both wrist timepieces are comfortable to wear, and I do enjoy having both in my wrist timepiece collection.

I do enjoy wearing the Hamilton Khaki; because, it’s the only wrist timepiece I own that doesn’t have a bezel; and, that, in and of itself, while in my wrist timepiece collection, is unique.

There is something nice about having a wrist timepiece that just tells time — there’s something nice about simplicity of design, and not having the business of a bezel, which, the absence of a bezel, adds to the attractive simplicity of the Hamilton Khaki. The simplicity highlights the bold and stunning face of the A-11-style Hamilton Khaki.

The Seiko Tortoise’s looks stunning in light green, and it’s well-made. I like the extra design features that Seiko added to the face, like the metal-cased time markers — they add a level of elegance to the Seiko Tortoise while being rugged to endure the outdoor adventures that might come its way while swinging on your wrist.

You get so much more goodies in the bag with the Seiko Tortoise over the Hamilton Khaki; and, the Seiko Tortoise comes in at a lesser price than the Hamilton Khaki, which makes it more appealing to me: great looks, quality build, at a competitive price.

Because of the Seiko Tortoise’s unique color, the screw-down crown, and the sapphire crystal, I find it mesmerizing two view and enjoy swinging it on my wrist.

Both the Seiko Tortoise and Hamilton Khaki serve different purposes for me.

I’m blessed to have both: Hamilton Khaki and Seiko Tortoise in my collection.

Check 6!

/s/ Alfonso Faustino