Convince me I'm wrong.

It's useful on a diver meant to be used for diving. Don't blame the watch for our collective misapplication of it. 

If ”used by number of people” is the criteria, the tourbillon is probably the least useful. At least the escape valve is used by saturation divers.

At some point ya just gotta go with "Cool Factor". Why do folks who can't swim wear a dive watch?? The "Factor" strikes again.

I love that people make the argument that it’s a dive watch and people use it for diving. U guys should read up on diving and equipment. 
I hate the escape valve with a burning passion. just saw it off my guy. 😂

Like a car that can do 260kph but here it tops out at 60 in the burbs and 110 on a highway.  Pointless engine?  Or just cool to be able to say that t goes that fast.  

For sure. The number of people who would dive in the watch is small. And smaller still, the number who would take it to depths where helium molecules start getting into their watch. Basically, it's wank :)

I would argue that everyone uses the tourbillion because its used as soon as u wind the watch. But yeah. That thing could be at the bottom of the ocean and it would have the same effect as being in a watch.

Even the ‘most useful’ complication would be on a mechanical item that’s generally considered to be obsolete!

But in the interests of discussion, I’m going with ‘day’ indication on a standard day/date. Who doesn’t know what day it is??

We can argue about the escape valve, or I can just prove you wrong :)

This has an emergency beacon in it. You unscrew that lower crown and pull out an antenna.  It has been used a few times, but I suspect far less than the helium escape valve.

Anyone with this watch on, who cares about safety beacons, will have a dedicated one.

Me. When on holiday I never know what day it is, but in that situation I usually don't want to know either. 

I can't, because you are right. Apart from professionnal divers using diving bells for days on end, an HEV is completely useless

A diver that doesn’t get wet is effectively useless. It’s like using a tractor to do the school run.

I must note that there was no "for intended purpose" qualifier, so you may be onto something. Every tourbillon gets used, even if it is utterly useless except for exhibition purposes.

Of course I'd assume that every HEV purchaser unscrews and tightens the silly valve on day one, the same way we all run into dark closets for lume checks. 

But in the interests of discussion, I’m going with ‘day’ indication on a standard day/date. Who doesn’t know what day it is?? 

But if you see it, it's being used! It's for confirmation and verification, of course, and there are certainly people that don't know the day. There are times I'm unsure of the month.

Yes, absolutely. The tourbillon is not only superfluous in a wristwatch, it also is a true complication, meaning that in increases the complexity of the movement significantly, without providing any value.

A HEV valve may not be needed, but it won't increase the servicing cost of the watch. 

Every tourbillon gets used, even if it is utterly useless except for exhibition purposes.

The tourbillon was designed to compensate for the rather stationary position of pocket watches. From my perspective it really has no use in a wristwatch. Yes, it works, but it is really of no use.

Since the helium escape valve is only for saturation divers it's likely to be used by almost no one.  I can't think of a more useless complication for a watch.

My estimation is that it could be used by 0.0001% of the population...if they wore their divers in the chambers. 

A helium escape valve is not a complication at all - it has nothing to do with the movement. 

If an Omega with helium escape valve was a person….

Would have made the Omega slightly cheaper without it too!

That is AN answer but not necessarily THE answer. There seems to be a split on if a feature is a complications ONLY when engineered into the movement. Others list barometers, thermometers, and compasses that are on the dial but not a part of the movement. 

Maybe that question will be a future poll. 

No way. If anything it would be...

It’s useless if you don’t dive. (I fit into this category). It‘s fun to tell someone their watch needs helium and look at their face. If they know they know. If they don’t know then it will provide some form of entrainment. Just tell them before they goto the jewelry store to get the helium.

I'll file this under the "other use" response in my highly scientific study. 

Sure, perhaps, maybe. 

I'll use the analogy of making a pen. "The cost to make one pen is multiple millions of dollars. The cost to make the second pen is $0.01." 

It’s not the specs that sell expensive watches, it’s the stories. 
 

Most watches have useless features for our modern lifestyles, be it HEVs, tourbillons, minute repeaters,  calendars and so on - but these were not only once useful but also considered high-tech in their day. Brands cling on to these stories of old school innovation to keep selling pricey watches to new generations. 

I’m with you, I’m not a fan of protruding HEVs; if a watch has to have one for the sake of heritage, I prefer hidden ones. 

Yep, concur that there is an attempt to appeal to nostalgia. 

The HEV is something I have a 0% chance of ever using. But I think I at least somewhat understand what it's intended for.

The least useful complication to me would be the "equation of time". I am not even slightly clear on what information it is supposed to impart, or of what use that information is intended to be.

I am going to have to look that one up. I have never heard of it.

Whoa! I think you may have me convinced. That complication is really odd. Well done EightEyes!