I found one of these while free diving. Wiped it off and wore it for several years, until I lost it while free diving.
The F-91W is such a fun little watch[1] and people have done the weirdest stuff with it. There's a guide to make the mod on Youtube[3]. There's also the TOTP in a F-91W[2]
1) https://www.youtube.com/watch?v=r6REKCs4-1M
FYI Casio recently brought out a minimalist series of the F-91W (same watch - just a bit less chrome on the face) e.g. https://www.casio.com/europe/watches/casio/product.F-91WB-1A...
Modified by oil-filling, though.
I've been stuck down the Casio modding rabbit hole as of late. I knew filling the watch with oil ('hydro-mod') lead to a crisper display with better viewing angles and increased water resistance, but to see a watch with minor splash resistance operate as such depths is insane.
Worth mentioning some drawbacks before you get your precision screwdrivers out. Doing it will make your watch get stupidly hot in the sun, the process can be messy, and sometimes certain mechanisms/features can break as a result of it. Best to check what others have done before you.
I just a fitness band in a f91w or w59 body.
These watches often have a quartz crystal - the little can would crush and the oil would damp oscillations, so they might have a laser trimmed RC loop - which would be cheaper as well as crush-proof?
I own legendary GW-5000U. It is amazing to see those cheaper alternatives are as good as 5000U.
I'm wondering is there any other brend except Casio that has watches as amazing as those are.
So the link to espionage is that a spy diver can dive to -5km wearing that watch and the watch will stay whole. ChatGPT can be really stupid sometimes.
The fact that a $15 watch, plus a little mineral oil, can handle 5,000 m underwater is just peak "good enough" engineering!
Was disappointed that he only brought a modified oil filled watch to 5km underwater. Would have been interesting if he’d have strapped a stock watch next to it so we could see when it would break.
I had a beloved F91W that I used for years. One day, when surfing in Morocco, it gave out and the screen became foggy before showing me an error code and never recovering. I guess I should have gone deeper.
Is there any reason a watch without moving parts filled without any gas pockets _would_ stop working?
Don't get me wrong, it's a nice demonstration but kinda expected outcome
It's amazing how often this comes up on HN... I'll have to get one.
This or Pebble? What is HNs heartfelt favourite?
> Incredibly, the F91W survives its journey to an official 4,950 meters—an astonishing 16,240 feet—and back.
Findings.
> 4,950 meters under the surface, the pressure is approximately 7,227 pounds per square inch, which is well over three tons pressing on the watch. For context, that’s a Dodge Ram 1500 or a young adult hippopotamus parked on every inch of your F91W. As Americans, we’ll do anything to avoid the metric system, but using scientific terminology, we’re talking about a shitload of pressure.
Appreciate the joke.
The new abl-100, besides more wearable size could have a nice tinkering potential
Is that a real CIA challenge coin? It has what look like strange imperfections.
I modded mine with olive oil when I bought it. Pretty indestructible.
Awe the Seal kiss, 20,000 Leagues vibe
Any hacks to fix the useless light?
Notably, there was no attempt to operate the watch at such depths. Pressing a side button would be an interesting test, for instance. Many "water resistant" watches, rated to a certain depth are only rated so, given the not inconsiderable caveat of not being able to operated - just looked at. The higher end, more expensive models claiming full waterproof ability don't typically have such functional restriction.
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For watch hackers, there is an alternate PCB with programmable microcontroller available for the F91W https://www.sensorwatch.net/
I got one for Christmas and it has been super fun to hack on. I programmed a new face for mine that displays the current tide level, and next high and low tides.