If you’re searching for a Seiko Submariner mod on a budget, this guide is perfect for beginners looking to build your own iconic dive watch homage. Similar to our popular Beginner’s Tool Kit, this is a curated list of compatible parts to create a reliable, stylish Seiko Submariner-style watch using affordable sources like AliExpress (with our affiliate links for easy sourcing).
Everything in this guide is intended to work together seamlessly for a straightforward assembly. If you swap parts, we’ve included key sizes to help you source alternatives or even custom options.
You’ll need basic tools to assemble—grab our Budget Starter Toolkit for everything essential. For full step-by-step instructions on building with preassembled cases, check our Guide to Seiko Submariner Mods in Pre-assembled Budget Cases list.
Movement: TMI (Hattori / Seiko) NH35A
The heart of your Seiko Submariner mod is the reliable NH35A automatic movement from Time Module Inc. (TMI), part of the Seiko/Hattori group. This is the go-to choice for Modders due to its robustness, availability and reasonable pricing.
Key Features:
- Automatic self-winding with manual hand-winding capability
- Hacking seconds (stops when setting time for precision)
- Date complication at 3 o’clock
- ~41-hour power reserve
- Beats at 21,600 bph for smooth sweeping seconds
- Rated accuracy: -20 to +40 seconds per day (often performs better when regulated)
The NH35A is essentially identical to the 4R35 found in current official Seiko watches—same dimensions, functions, and compatibility with dials/hands. Minor differences include jewel count (23-24) and branding restrictions (NH35 is sold to third parties), but performance is the same.
Recommended AliExpress link: NH35 Movement (~£48)
Hand Hole Sizes (critical for compatibility):
- Hour: 1.50mm
- Minute: 0.9mm
- Seconds: 0.2mm
Learn more in our NH3X Movements Blog.
There are chinese copies of the NH3X movement so be sure to shop for Japanese NH35.
Case and Bracelet: 42mm Stainless Steel Submariner-Style
We recommend a stainless steel case and bracelet set complete with sapphire crystal, ceramic bezel insert (in your choice of colour—black is the classic for Submariner vibes). The case has a120-click unidirectional bezel, and optional exhibition caseback and date magnifier (aka cyclops). You also have the option to have the middle link in the bracelet polished like it were a platinum Smurf!
This 42mm size offers a modern, wrist-present feel while staying true to dive watch proportions. This comes pre-fitted with crown and tube as well as gaskets for easy supply and assembly.
Pro Tip: We recommend buying a bracelet and case set if you intend to wear your watch on a bracelet or see yourself wanting one in the future. Solid end links ensure a flush fit and better comfort. Read more in our Blog about Bracelets and Seiko Modding.
Recommended AliExpress options
- Recommended : 42mm Case + Oyster Bracelet Set (less than £50 including bracelet)
Dial: Personal Choice
The dial is really personal choice and what makes your Seiko Submariner mod unique! For a classic look, go sterile (no logo) black with applied markers and lume.
Key Specs for Compatibility:
- Diameter: 28.5mm
- Thickness: 0.4mm
- Suitable feet position to fit NH35 movement with a 3 o’clock crown
If you want something different or a custom dial made, these sizes ensure compatibility with most NH35 cases.
Here are some popular budget options (all luminous for visibility):
Dial Options for a Traditional Submariner Homage (~£10-£20)
Hands: Mercedes Style for NH35
The hands will need to be suitable for the NH range of movements—the hand hole sizes are detailed above in the movement information (hour 1.50mm, minute 0.89mm, seconds 0.21mm).
We chose the standard Mercedes hands for this mod list—the iconic arrow-hour hand gives that true Submariner homage feel, with strong lume for low-light readability. These hands can be purchased as a package along side the dials with text listed above.
Recommended: Lumed Mercedes set in a silver colour for the classic sub look. If it is your first mod it would be advisable to have a second set of hands which can purchased on the link below.
AliExpress example: Mercedes Hands Set (~£5)
Is This Perfect?
Its good enough to have a go with and wont break the bank—you are not going to get the quality of a genuine Submariner or even a Steinhart Ocean One, but you will have a watch that is waterproof (typically 200m+ with proper assembly) deeper than you plan to go (unless you are a professional diver). It’s a fun, rewarding project with great bang-for-buck performance, powered by a proven Seiko movement.
Total parts cost: ~£115- £120 depending on options.
Ready to start your Seiko Submariner mod? Grab the parts, toolkit, and dive in with this guide! Questions? Drop them in the comments or contact us. Happy modding! 🚀
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