Mass confusion about computers????

[KeithG]

Was that 16 vs 1 at the bottom, or 99 vs 84 at the SS? One of those is not quite like the other. Think about it for a second and I'm sure you'll realize that the statement is meaningless without that little detail.

You also need to provide info on your SI between dives. I know of a 2 tank boat op that schedules a 45 minute SI. Not Suunto friendly.

 

[scubadada]

You also need to provide info on your SI between dives. I know of a 2 tank boat op that schedules a 45 minute SI. Not Suunto friendly.

In SE FL, SIs are frequently less than an hour, around 45 min is common

 

[Umuntu]

If you look at the chart in the thread that @Bob DBF linked above you will find that the Suunto running RGBM gives 40-48 minutes @ 60 feet (I am unsure why there is a range given?) and the Aladin running Beuhlman gives 51 minutes. Not much of a difference between 48 and 51. And the Mares is listed at 57 minutes - the least conservative of these 3.

The graph in that post from 2009 appears to be misleading with respect to Mares. Mares currently use Mares RGBM, not modified Haldanean (except to the extent that all models are derivatives of Haldanes work). Mares RGBM is more conservative than SUUNTO RGBM. Not that it really matters much because they are close to each other.

 

[Umuntu]

In SE FL, SIs are frequently less than an hour, around 45 min is common

Some operators appear to use shorter SI's as a way to limit bottom time … shorter dive times and shorter trips. I make it known I require at least a 1 hour SI when I book my dives.

I'm happy to start gearing up at 45 minutes but I hit the water after an hour.

 

[Steve_C]

At the bottom where it matters. By the safety stop they are loaded with time, assuming that I have not put the ZOOP into deco with the other in NDL. They are both on my wrist a couple inches apart. Another difference is as i start to go up the nonZoop starts upping the NDL quicker.

 

[stuartv]

Truth is in the world of rec computers they are all going to be "similar" in allowable time under pressure.

If you read all the info in the thread Bob DBF linked (not just what is on the first page), you will see that that is not true. They will mostly all be similar for the first dive of the day. As you do more dives, the differences grow. The data in the linked thread shows that by the 3rd dive of the day, the differences can be QUITE large.

I’m not sure I’m comfortable buying used electronics....still on the fence about that.

Shearwater computers have a TRANSFERABLE 2 year warranty. And you don't have to do anything to "transfer" it. If you buy a Shearwater that is less than 2 years old, you're covered. I wouldn't hesitate to buy a used Shearwater if it was under warranty (and what I wanted). I wouldn't hesitate much on one that was out of warranty, either - assuming it was the right price.

All the other brands (AFAIK) only warranty the computer to the original purchaser, so I would not look at any of those unless it was REALLY cheap.

 

[Steve_C]

Some operators appear to use shorter SI's as a way to limit bottom time … shorter dive times and shorter trips. I make it known I require at least a 1 hour SI when I book my dives.

If they are giving you an hour in the water per dive, and they are shallow reefs, even on air a half hour SI will not limit your bottom time.

I have been on some shallow wrecks 50-60 ft where the air divers were told to take an hour SI but the nitrox divers often did 30 minutes or so with no loss of NDL (well not much loss). But you could take an hour on nitrox if you wanted.

 

[Steve_C]

You also need to provide info on your SI between dives. I know of a 2 tank boat op that schedules a 45 minute SI. Not Suunto friendly.

Normally an hour but I did not check. Could have been slightly less. I am decent on air and dive an HP 100 on ntirox so I am often one of the last ones up on dive one.

 

[dmaziuk]

If they are giving you an hour in the water per dive, and they are shallow reefs, even on air a half hour SI will not limit your bottom time.

Not necessarily: if you came up fast enough to "grow the bubble past critical radius", it may slow your off-gassing rate and give you less SI credit than table 2 does. So you start your next dive in a different pressure group than you think.

That's why you can't meaningfully compare their NDLs without also looking at their calculated gas loading: there may be compounding effects. There may not be. Who knows.

 

[kelemvor]

I count my lucky stars that the local suunto dealer is also a scubapro dealer and they had galileo luna's on sale the day I went. I had gone to buy some suunto, I forget which model, and left with the scubapro instead. I had no idea that some computers were significantly more conservative than others at the time. Looking back, I feel like I won the lottery that day.

Not that I'm saying suunto's are bad. There are plenty of folks who love them. They're just not for me.