Suggestions for getting my first dive computer

[scubadada]

Hi @Diving Dubai

I have to side with @doctormike Unless your dive number is inaccurate, it's not all that impressive, perhaps it's your training line. I would always be careful in generalizing based on your own experience.

Best, good diving, Craig

 

[stuartv]

If your vacation diving only then algorithms, don't really come into play as the DM's set the dive times and depth by their NDL

Yes you can get larger cylinders but that doesn't change the fact that the dives are time limited (generally 1 hour) and the group will be guided through the dive by the DM. It is the DM's computer which generally the controlling factor on NDL. The DM isn't going to go into Deco if you have a liberal computer, equally the DM isn't going to dive a liberal computer putting his guests on a conservative computer into Deco.

Dives are depth limited (for instance Dive 1 - 30m max, dive 2 20-25m and dive 3 -18m etc) each day to ensure people have the max NDL and to keep with the schedule

So my statement still stands that for recreational dive trips, it is the guide's computer that is the controlling factor

If you ever go diving outside of the USA, you'll find things work differently. I don't recomend you do though because you wouldn't like it.

Given the OP lives in Scotland, the choice of vacation dives will generally be
Red Sea
South East Asia
Maybe the Med
Maybe Maldives

You have made blanket statements that are simply not true everywhere.

My dive buddies from the UK are ones that I met diving on vacation in the Caribbean, North Carolina, and the Saint Lawrence River (Canada).

I haven't been to the Red Sea, Asia, the Med, or the Maldives, so if you want to limit your statements to how vacation diving is done in the those places, I won't debate you.

But, it is a fact that UK divers do sometimes vacation in places where I have personally been - like the Caribbean, for example. And in some of those places, your blanket statements about how the diving works - and specifically that the dives will always be guided and time limited - are simply hogwash.

I don't mind if you want to believe hogwash, but, as I said in the first place, you do a disservice to the OP and others when you promulgate that hogwash.

 

[dmaziuk]

I was wondering if anyone could give me any suggestions on a good dive computer. I only really dive when I go on holiday so I am looking for one that is watch sized so I can wear it for most of the time. I have had a look at different computers but was hoping for other people's opinion as I am not sure what would be the best.

"Best" is subjective. As others said, watch-sized ones are generally too big to wear as watch, esp. on a female wrist. Deepblu cosmic would at least look like a fitbit/aieeWatch if that's your style. And it should be readable despite the small screen.

 

[KenGordon]

All these people can learn to dive but can't learn the basics concerning decompression algorithms? I think you underestimate many people

Diving is easier than calculus. It is not necessary to understand the DIFFERENT algorithms behind computers, just a vague idea of shorter limits for deeper dives and shorter limits for repeat diving is enough. Whether they are bubble models, dissolved gas modes or just based on probability analysis of lots of dives does not matter to somebody who is still getting the hang of not smashing into the bottom.

Once a diver has done a good number of dives and gets a feel for what limits them, gas, NDL or whatever then they can start to figure out if the answer is deco stops or more gas. Then they can read the books and try to become informed. At the beginning they might as well be starting learning to drive by looking at the combustion characteristics of petrol vs diesel.

 

[Chavodel8en]

I think its good information for even a brand spanking new diver to tell them very simply: Different computers are more conservative/liberal in how long they will let you dive at a given depth. If you think this may matter to you (now or into the future), look into it before buying. If it doesn't matter to the diver, they can ignore the info.

Someone doesn't need to understand the ins and outs of algorithms & theory and all the other scuba-analytical nerd stuff. I don't. But I understand very simply & practically that some computers are more conservative/ liberal, and the balance is risk v. longer dive times.

In fact, in the computer/gauge section I believe there is a pinned post where someone listed computers based on a scale from more liberal to more conservative. Very easy to understand chart. It would have helped before I bought. Lucky for me, I just happened to pick a liberal computer appropriate to my diving. Since I rarely do more than 2 dives/day, I now know that I prefer a liberal computer, so I can maximize my NDL on the few deeper dives that I do. I would hate to cut short even by a few minutes my one deep wreck dive per year on vacation bc I bought a Suunto.

 

[KenGordon]

But, it is a fact that UK divers do sometimes vacation in places where I have personally been - like the Caribbean, for example. And in some of those places, your blanket statements about how the diving works - and specifically that the dives will always be guided and time limited - are simply hogwash.

In all the dives I did in Cozumel, the cenotes and mainland Mexico I never had to stop a dive to avoid deco, I might have done one 2 minute stop at the end of drift on the mainland. I was using Ali 100s. All the guides were on Suuntos. The dives were all routes to follow. If you had enough gas you got to the end of the reef, if you had more you might look at some sand but the boat would be waiting and bored.

In Indonesia last year I did 40 dives without ever getting into deco, although a young lady being 'looked after' by the DM did have several minutes at one point due to being on air.

In the Red Sea the previous year we had exactly 1 minute of stops at the end of an 80 minute dive. My buddy was on a twin set for that trip so we were never gas limited. She dives a Suunto Vyper. There the limits were running out of reef and how long you needed to wait to have a shark free window to get back into the rib.

On Gozo doing 40m bounces down to a wreck and then spending time in the shallows photographing stuff we did get deco obligations, but gone well before surfacing.

Most of the vacation diving organised by dive ops is designed to prevent the clients getting bent. The easiest way is to do that is to use small cylinders, another way is to have a definite route plan that takes an appropriate time for the depth. Back when I first went to the Caribbean they didn't run trips to the deeper sites in the afternoon.

In the U.K. almost everyone dives a Suunto. A few people branch out and are sold some rebadged thing marketed by the same people that make fins and BCDs but made by who know who. Eventually they realise that they cannot trust a HAL 9000 (tm) even if it means they get to the coffee and cake before their buddies who are spending longer taking a close look at the plankton.

Not only is the algorithm the least important part of a dive computer, it is the one user's are least well qualified to judge. We can look at the screen and decide a small monochrome LCD is not as nice as a big colour display, we can wonder if changing the battery twice on a trip is a big deal or whether once every couple of years isn't better, bungee vs straps, one, two or three buttons, tap interfaces, gauge mode etc, we can think through the implications of those things. When it comes to the algorithm though we cannot. Do you have a PFO? Does it matter? Do you feel lucky?

 

[KenGordon]

The mods deleted the part of my post above which suggested that listening to people on these forums who pontificate about algorithms might be listening to people who do not understand how they work.

 

[Neilwood]

In all the dives I did in Cozumel, the cenotes and mainland Mexico I never had to stop a dive to avoid deco, I might have done one 2 minute stop at the end of drift on the mainland. I was using Ali 100s. All the guides were on Suuntos. The dives were all routes to follow. If you had enough gas you got to the end of the reef, if you had more you might look at some sand but the boat would be waiting and bored.

In Indonesia last year I did 40 dives without ever getting into deco, although a young lady being 'looked after' by the DM did have several minutes at one point due to being on air.

In the Red Sea the previous year we had exactly 1 minute of stops at the end of an 80 minute dive. My buddy was on a twin set for that trip so we were never gas limited. She dives a Suunto Vyper. There the limits were running out of reef and how long you needed to wait to have a shark free window to get back into the rib.

On Gozo doing 40m bounces down to a wreck and then spending time in the shallows photographing stuff we did get deco obligations, but gone well before surfacing.

Most of the vacation diving organised by dive ops is designed to prevent the clients getting bent. The easiest way is to do that is to use small cylinders, another way is to have a definite route plan that takes an appropriate time for the depth. Back when I first went to the Caribbean they didn't run trips to the deeper sites in the afternoon.

In the U.K. almost everyone dives a Suunto. A few people branch out and are sold some rebadged thing marketed by the same people that make fins and BCDs but made by who know who. Eventually they realise that they cannot trust a HAL 9000 (tm) even if it means they get to the coffee and cake before their buddies who are spending longer taking a close look at the plankton.

Not only is the algorithm the least important part of a dive computer, it is the one user's are least well qualified to judge. We can look at the screen and decide a small monochrome LCD is not as nice as a big colour display, we can wonder if changing the battery twice on a trip is a big deal or whether once every couple of years isn't better, bungee vs straps, one, two or three buttons, tap interfaces, gauge mode etc, we can think through the implications of those things. When it comes to the algorithm though we cannot. Do you have a PFO? Does it matter? Do you feel lucky?

These are the reasons I made my choice of conservative. I would rather hedge my bets with a conservative computer than sail closer to the edge with a liberal computer. I can live with my dive being slightly shorter compared to the trade off of a possible chamber ride by pushing my limit

To decide on an algorithm with your eyes truly wide open, you need the following:
1) understanding of the algorithm including why it provides the timings it does (ascent rates, penalties for "aggressive" actions etc)
2) Knowledge of DCS and potential signs and symptoms including minor ones.
3) Enough dives to properly ascertain & analyse how you feel after a particular dive
4) the ability to analyse whether that feeling is "am I feeling unusually tired or sore compared to usual?" and is it down to my dive profile, time, hydration level, tiredness etc?
5) the knowledge that even within NDL, you can be asymptomatic but still have long term (particularly in joints).
6) how the algorithm treats repeat dives
7) the ability to look at your own health and decide how you rank with regards to DCS risk factors such as weight, fitness, age etc generally.
8) the willingness to adapt your diving even within NDL depending on how you feel on that particular day- "I feel a bit under the weather so I will dive more conservatively"

 

[boulderjohn]

I find it interesting that some of the people telling the OP what the diving will be like seem to have limited experience, despite their number of dives. My experiences diving around the world differ from what some people seem to think is done in all places. Here are just a few examples:

• In Cozumel, some of the operators, notably Aldora, offer HP 120 foot tanks in order to extend dive times. First dives are usually in the 80-100 foot range, and NDL is very much a concern.
• In South Florida, most of the operators I have used do not put DMs in the water leading dives. Many of the operators offer a wide variety of tank sizes. Depths of first dives can go all the way to recreational limits--130 feet.
• I have dived with a number of operations in the Hawai'ian Islands that had us diving to the limits of both our gas and our computers.
• I just got back from diving in Bali a couple of months ago. Yes, we did mostly group guided dives, but we also did unguided shore dives where depths and times were up to us.

Does your computer make a difference on dives like that? Last year while diving in South Florida for a week with two friends, we used three different computers, and we were limited by the most conservative. As soon as that week was over and the other two went back home, the one with the most conservative computer, who had been totally frustrated during that week, sold his computer and got a different one.

 

[drrich2]

Note to original poster: your gas consumption rate may have a big impact on to what extent NDL limits come into play (i.e.: if you run low on air & have to abort dives before you get near the NDL, it's less of a concern). Odds are your gas consumption rate will drop significantly over time, as your experience & comfort level diving improve.

There are other factors that may give you lower consumption rate - petite size, female gender (some debate it, and women tend to average smaller body size than men), fit & trim, and then some people for reasons we may never understand seem to have abnormally low natural rates. You'll find threads on the forum talking about how wearing adequate exposure protection to maintain body heat helps some people. The more extensive exposure suit protection & weighting to compensate can raise consumption rate.

My point is, how experienced you are, how big and fit you are, and the kind of diving you do all bear on how long a tank of air or nitrox will last you, and how likely NDLs are to limit your dive times.

Richard.