Is a Computer essential kit?

[CT-Rich]

What happens if 2 computers give different times are you socially obligated to get bent.

Regardless of how the NDL are tracked, when someone hits it, the dive is over. A table based dive will most of the time be way more conservative than what real time tracking would be on a PDC. Turning a dive because you insist on relying on a plastic card does not bode well for an ongoing relationship. If they aren’t going to have the right tools to track a dive likely means they are not going to pay to survive their gear, will borrow your tools and use up all your spares in your save-a-dive kit. And they won’t bring snacks or beer….

 

[Celt]

Regardless of how the NDL are tracked, when someone hits it, the dive is over. A table based dive will most of the time be way more conservative than what real time tracking would be on a PDC. Turning a dive because you insist on relying on a plastic card does not bode well for an ongoing relationship. If they aren’t going to have the right tools to track a dive likely means they are not going to pay to survive their gear, will borrow your tools and use up all your spares in your save-a-dive kit. And they won’t bring snacks or beer….

I planned a dive to the SS Feltria. 67metres, I had 3 bottom times planned. A fellow diver asked to go with me who was using a uwatec alladin. Conditions were perfect so I pulled out my slate on the bottom and opted for the long bottom time. 3 minutes before my time was up he came to me showing his computer he had 20 minutes more deco than my plan ( was he right to have stayed on the bottom or should he be that guy that gets back to the boat early) I planned a 60ft per minute assent but his computer wouldn’t allow it and by the time he got to the deco stage he had 37 minutes deco more than me at the 10 foot stop and ran out of gas. Luckily I had plenty. He should have left early and not worried about social niceties. Never dive someone else’s plan

 

[CT-Rich]

I planned a dive to the SS Feltria. 67metres, I had 3 bottom times planned. A fellow diver asked to go with me who was using a uwatec alladin. Conditions were perfect so I pulled out my slate on the bottom and opted for the long bottom time. 3 minutes before my time was up he came to me showing his computer he had 20 minutes more deco than my plan ( was he right to have stayed on the bottom or should he be that guy that gets back to the boat early) I planned a 60ft per minute assent but his computer wouldn’t allow it and by the time he got to the deco stage he had 37 minutes deco more than me at the 10 foot stop and ran out of gas. Luckily I had plenty. He should have left early and not worried about social niceties. Never dive someone else’s plan

So, if he had no computer and had been at the kitchen table when you made it, would his obligation been different from yours or the same? Did he have other prior dives that his computer was taking into consideration? This was not a recreational dive (this is a basic forum). He should have been diving his own plan, especially at that depth.

As I said earlier, dive planning involves risk tolerance and normalization. A computer simply takes the human factor out. How close either of you really were to getting bent is not going to be known for sure (unless somebody was bent). Some one pointed out the extra minute on a interval doesn’t really change much other than your repetigive dive group. A diver just chooses who he listens to. If you are wearing a perdition on your wrist and the cheap puck back up says you violated your NDL, few divers would know unless they took the puck out to take a look. They are using the Perdix.

For all we know, your dive buddy with his Alladin saved you from a DCS hit. Staying with him on his deco saved you from having too short a deco.

 

[Celt]

For all we know, your dive buddy with his Alladin saved you from a DCS hit. Staying with him on his deco saved you from having too short a deco.

I dived my plan, why would i change my plan. I had 3 minutes bottom time left and sent him up the shot ahead of me. I done no extra deco just handed of the gas. No point in me using gas if he was low.

 

[inquis]

A dive computer gives flexibility. Yes, one can plan one or more profiles with tables or a phone/desktop planner -- even multi-level profiles -- but at some point, the effort involved to do that and write all that down PRE-DIVE is just not worth it to me. When affordable computers are not that much more than a depth gauge + bottom timer, a little more money buys a lot more flexibility (and might even be the cheaper route when used gear is an option).

It's too bad the OP bailed. It would have been nice to know how much they may have valued not being locked into an apriori plan.

 

[Wibble]

Dive computers bring completely different planning techniques to the table.

"Fancy this 60m/200ft dive tomorrow Fred?"
"Yeah, why not…"
That night spent gassing up for 60m, but better add some contingency, call it 70m/230ft just in case. Quick check that there’s enough bailout and what the max bottom time would be for 70m with that bailout, also for 60m…. Sort out kit and dive computers
Next day check with the skipper for the max runtime. If buddying up with someone else then make sure they know it’s the target runtime and check what Gradient Factors they’re diving. If the skipper’s runtime is longer than my bailout runtime, then bailout becomes the max runtime.
Then jump in.

Dive's run for the total runtime as per the computer’s calculations. Max depth would be the contingency, 70m/230ft.

Enjoy the dive monitoring the runtime and TTS (time to surface) so it doesn’t exceed the max runtime. Dive computer(s) give you the running numbers and estimate when to leave the bottom or head back to the shot line.

If buddying then maybe some communication during the dive for TTS comparison.



If diving like this, then the computerS become essential dive equipment and hence carry two minimum, maybe three.

 

[hedonist222]

What happens if 2 computers give different times are you socially obligated to get bent.

Don't be pedantic now....

The difference between two recreational computers will be +/- a couple of minutes

But the difference between any recreational dive computer and square-profile plan will likely be more than a few minutes

 

[Wibble]

Don't be pedantic now....

The difference between two recreational computers will be +/- a couple of minutes

But the difference between any recreational dive computer and square-profile plan will likely be more than a few minutes

My wrist mounted Petrel is always later in clearing than my mouthpiece mounted Nerd. Obviously my hands are slightly lower than my face.

 

[Joneill]

If I wanted to make those dives I’d use my own boat if that’s what it takes. But the lack of a computer wouldn’t stop me.

It would stop you from boat diving in every single tropical destination that I’ve been to!

 

[Celt]

Don't be pedantic now....

The difference between two recreational computers will be +/- a couple of minutes

But the difference between any recreational dive computer and square-profile plan will likely be more than a few minutes

Making any diving decisions because you feel socially obligated is a critical mistake. Every dive I made using US navy tables I had longer bottom times and less deco than a fellow diver using a computer. So people saying that using tables is a disadvantage are not talking from experience where dive time is concerned. Tables are consistent but I’ve seen two different make computers on different settings come up with totally different dive plans. Which one of those divers is not socially acceptable.