NATO Straps on the Fifty Fathoms: The Diver's Classic
Of all the straps you can fit to a Scuba Fifty Fathoms, the nylon NATO is the only one with a genuine claim to belong there. It was designed for military divers, it keeps the watch attached when hardware fails, and it costs less than almost anything else in our Fifty Fathoms straps range. It is also the strap most often bought for the wrong reasons and fitted in the wrong way. What follows is what the design actually does, how it behaves on a bioceramic diver rated to 9.1 bar, and where it is the wrong answer.
What a NATO is, and what the single piece of nylon is for
One strap, two bars, no failure point
A conventional strap comes in two halves, each attached to one side of the case. If a bar lets go, the watch falls. A NATO is one continuous length of nylon that passes under the case back, through both lug openings, with a shorter keeper tail threaded over the top. Both bars would have to fail simultaneously for the watch to come off your wrist, and even then the strap would remain looped through your arm. That redundancy is the entire reason the design exists, and it is the reason it persists on watches that go in water.
The name, briefly
The pattern derives from a British Ministry of Defence specification issued in the 1970s, listing a nylon strap in grey with chrome hardware. The "NATO" label came later and stuck through common usage rather than official designation. The military version was one colour; everything since has been the market taking a good idea and painting it.
Why it suits this watch in particular
Screw bars change the calculation
The Fifty Fathoms uses screw bars rather than spring bars, which are already more secure than most fittings. That makes the NATO's safety argument less urgent than it is on a spring-bar watch — but it does not remove it, because screw caps can loosen over months of wear and vibration. A NATO gives you a second line of defence at no cost. It also means fitting one is a five-minute job with two 0.9mm hex drivers rather than a quick swap, so plan to leave it on for a season rather than changing it on a whim.
Weight, and a light case
Bioceramic is a fraction of the density of steel, and the Fifty Fathoms weighs remarkably little for a 42.3mm diver. On rubber it perches rather than settles. Nylon does not add meaningful mass, but it does something better: because the strap passes underneath and is tensioned on both sides of the case, the watch is clamped to the wrist rather than resting on it. It stops sliding round to the underside of your arm during the day, which is the most common complaint about this watch on its stock band.
The one real drawback: height
Here is the honest cost. Running nylon under the case back lifts the watch away from the wrist by the thickness of the strap — usually between 1.2mm and 1.6mm. On a case already 14.4mm deep, that matters. The watch sits higher, catches on a shirt cuff more readily, and tips slightly if the strap is not tensioned evenly. Anyone with a wrist under about 16.5cm will feel this immediately.
There are two ways round it. A single-pass strap, sometimes sold as a Zulu single-pass or marine nationale style, threads through both lugs without the return layer under the case, keeping the profile flat while retaining most of the security. Or you choose a thinner weave: the difference between a cheap 1.6mm nylon and a well-made 1.2mm one is obvious on the wrist within an hour. Both options are stocked among our Fifty Fathoms NATO straps, cut to the 22mm fitting this case needs.
Weave, hardware and what separates a good one from a cheap one
The nylon itself
Seatbelt-weave nylon is tightly woven, slightly glossy and very smooth against skin, but it is dense and dries slowly. Ballistic nylon is coarser, tougher and more textured, and it wears in rather than out. Ribbed military-pattern nylon sits between the two and is the safest default for a diver. Whichever you choose, check the edges: a properly finished strap has heat-sealed or stitched edges that will not fray after a season of salt water, and a cheap one has a raw cut that starts shedding threads within weeks.
Hardware, and the part that fails first
The buckle and the two keeper rings do all the mechanical work. Brushed 316L stainless steel is the material to look for; plated base metal looks identical in a photograph and starts pitting within a summer of sea water. Look also at how the hardware is attached — the loops should be fully welded or seamlessly formed rather than folded and pressed, because a folded ring will eventually open under load. On a watch of this weight, hardware quality is not a detail.
Length and the tail problem
A standard NATO runs around 280mm, which is generous and designed for wearing over a wetsuit sleeve. On a bare wrist that leaves a long tail, and the usual solution — folding it back through the keeper — creates a thick lump that presses into the underside of your arm. Measure your wrist and buy accordingly; a 260mm strap suits most wrists between 17cm and 19cm without any folding at all. If you already own a long one, trimming the excess and sealing the end with a lighter flame is a two-minute fix that costs nothing.
In the water, which is where it earns its keep
Nylon absorbs some water but dries faster than any other textile and considerably faster than leather or canvas. After a swim it will feel damp for perhaps twenty minutes and be dry within the hour in warm air. It shrugs off chlorine, it can be hand-washed as often as you like, and unlike rubber it never develops the sticky film that comes from sun cream.
The discipline that matters is rinsing. Salt water dries into fine crystals inside the weave, and those crystals are abrasive — they grind at the fibres every time the strap flexes, and they will also work their way into the keeper rings and the buckle tang. Rinse the strap under cold fresh water after every sea swim, with the buckle open, and work the water through the weave with your fingers. Dry it flat and shaded, never on a radiator, and give it four to six hours before putting the watch away.
Colour, and the ocean editions
Each edition arrives with a dial and bezel colour already doing the talking, which makes nylon straightforward: go quieter than the watch. Grey, navy, olive and black all work across the whole range and look correct rather than costumed. Striped patterns are where NATOs go wrong most often — a bold stripe under a bright bezel gives the eye two things competing for attention, and the watch ends up looking like a novelty. If you want a stripe, pick one whose colours are already present on the dial, and accept that it will be the strap you wear least.
Because the case dimensions and fitting are identical across every edition, a nylon band bought for one watch moves freely to another. That is the practical argument for owning two or three: at this price, a small rotation costs less than a single rubber strap and covers most of what you will actually wear the watch to.
Frequently asked questions
What width NATO does the Scuba Fifty Fathoms take?
22mm at the lugs. A narrower strap will slide sideways in the lug gap and wear unevenly against the case.
Do I need tools to fit a NATO?
Yes. This case uses screw bars, so you need two 0.9mm hex drivers to remove the bars, thread the strap and refit them.
Will a NATO make the watch sit too high?
It adds roughly 1.2mm to 1.6mm. If that concerns you, choose a single-pass strap, which keeps the profile flat while retaining most of the security.
Can I swim in a nylon strap?
Yes, and it is one of the better choices for it. Rinse it in fresh water afterwards and dry it flat, or salt will stay in the weave.
How long does a nylon strap last?
A well-made one with sealed edges and steel hardware will take two or three years of regular wear and dozens of washes. Fraying at the keeper is the usual sign it is done.
The cheapest serious upgrade this watch takes
A NATO will not transform the Fifty Fathoms the way a bracelet does, and it is not the most comfortable thing you can wear in a heatwave. What it offers is a set of practical advantages that no other material matches at once: it cannot fail catastrophically, it dries in an hour, it washes clean, it costs very little, and it holds a light watch still on the wrist. Choose 22mm, sealed edges and steel hardware, size it so you are not folding a long tail underneath, and rinse it after the sea. Do that and it will still look right in three years, which is more than most straps at any price can promise.
Also read our previous article: Steel Bracelets on the MoonSwatch: Weight, Comfort and Look