Necessity of a back up computer/watch for NDL diving

[dmaziuk]

I go with #1. I don't dive locally - therefore, I don't want to risk being sidelined by a nonfunctioning dive computer after spending money on a dive trip! For me, a backup DC is a no brainer!

I take trips too. Most of the time I won't have a problem switching to a clean rental computer mid-trip. The rest of the time I won't have a problem sitting one out.

Your Trips May Vary.

 

[Joneill]

I take trips too. Most of the time I won't have a problem switching to a clean rental computer mid-trip. The rest of the time I won't have a problem sitting one out.

Your Trips May Vary.

Good for you, but not sure I get your point? Switching to a rental computer mid trip can actually be a bigger deal if you've been doing 4 dives a day - may impact more than just your next dive as the rental won't have you history. It's also not free and you likely will not be at all familiar with how it works.

I really don't get why you would want to sit out dives after spending money on them? You're not going to get a refund on missed boat dives. As others have said, a backup can be as cheap as $50 - so I don't get the desire to talk people out of doing something that there is really no valid argument against doing if they so choose???

 

[Diver-Drex]

I don’t recall anyone suggesting foregoing computers for tables, at least I did not. Or that anyone is arguing against a backup computer. I said that, in the context of the OP, a second computer is not nessecary and don’t overlook the usefulness of tables as backup. I presented three cases to illustrate this.

In particular I was addressing a post about having multiple backups. I think it was important to clarify that a second backup computer that is sitting in your dive bag is not a viable backup without an extended SI.

Dve with two computers, I do. But I always have tables, a watch and a depth gauge on hand. If one of your computers fails you can continue to dive with only one computer or you can not dive. Or you can use the tables.

An additional choice is to actually use the planning function on your computer to see the NDL at your planned depth. If you have at least a watch on and your computer fails you know, assuming a hard bottom at your planned depth, where you stand in terms of your NDL.

 

[tursiops]

If it did fail I would have a good idea of my depth and time and could easily average that and continue the dive, making a normal ascent. If I had to skip the next dive, so what. I could always dive alongside my buddy and use her computer, or dive shallower and not use one at all.

In a Basic Scuba thread, I'm not sure you ought to be advocating three things (use buddy's computer, use depth averaging, use no computer/depth info at all) that ALL violate the procedures taught in a basic OW class.

 

[MaxBottomtime]

In a Basic Scuba thread, I'm not sure you ought to be advocating three things (use buddy's computer, use depth averaging, use no computer/depth info at all) that ALL violate the procedures taught in a basic OW class.

I used one of these in my OW class, and did so for the next 400 or so dives before I ever dived with a computer.

 

[Joneill]

Not everyone wants to carry extra gear on a dive.

Wearing an extra DC on your wrist or in your BC pocket is hardly a big deal. Obviously, it's a personal choice, but seems a specious argument against a backup.

In nearly 2400 dives, I haven't had a gear failure. Apparently, I'm lucky. Perhaps I just take care of my gear and it takes care of me.

How exactly do you take care of your DC to ensure it won't fail? I rinse mine after every dive, and store it in it's padded case when not using it. That doesn't mean the pressure sensor or other electronics won't fail. It also doesn't preclude accidentally dropping or damaging it in use.

I look at my computer a lot during each dive. If it did fail I would have a good idea of my depth and time and could easily average that and continue the dive, making a normal ascent. If I had to skip the next dive, so what.

So what??? Maybe not a big deal for you but not everyone feels that way. I only get to do a few dive trips a year (no local diving for me) so If I spent ~$100 on a 2 tank boat dive, why would I want to needlessly sit out the second dive (or subsequent dives after that)?

I could always dive alongside my buddy and use her computer, or dive shallower and not use one at all.

All of which is 100% not necessary if you choose to dive with a backup - your choice though!

However, diving following your buddy's DC is widely discouraged from everything I've read and, imho, irresponsible to suggest in the Basic Scuba Forum!

 

[chillyinCanada]

I used one of these in my OW class, and did so for the next 400 or so dives before I ever dived with a computer.
View attachment 510605

So did I, but we're old.

 

[Joneill]

I used one of these in my OW class, and did so for the next 400 or so dives before I ever dived with a computer.
View attachment 510605

And people used to use these as primary transportation too:

It's 2019 - why live in the past when there are solutions that add convenience and enhance safety versus what was used in the past!

 

[dmaziuk]

Good for you, but not sure I get your point? Switching to a rental computer mid trip can actually be a bigger deal if you've been doing 4 dives a day - may impact more than just your next dive as the rental won't have you history.

That's the logic problem: the impact is exactly the same after 1 dive or 4 days of 4 dives. You don't know your exact residual loading, but you know the upper limit on it: you're at most in pressure group Z.

 

[tursiops]

I used one of these in my OW class, and did so for the next 400 or so dives before I ever dived with a computer.
View attachment 510605

As did I, but I would not use it today nor recommend it today to a new diver.