SPG and Computer?

[Guy Alcala]

The computer functions as the depth gauge, timer and computes your NDL.

If you ever need to ascend without a depth gauge, your buddy should be able to use his to set your rate. Failing that, ascend slower than your smallest bubbles. Then once you are close to the surface, you can count off your safety stop.

FYI: Basic dive computers are very reliable, they rarely fail during a dive. Common problems are dead battery, dead on start up or flooding after an improper battery change. For AI wireless, there is some additional complexity with the transmitter for the air pressure that can fail during a dive (loosing the link, etc.)


BTW: I have had one analog depth gauge die on me, never a computer. Just my experience, nothing significant.

I do a lot of solo diving, but more than that, I refuse to rely underwater on anything that needs a battery without a backup, preferably mechanical. Nor do I want to be dependent on a buddy for important data even if they're someone I can rely on; self-sufficiency is the name of the game for me. So I dive with a brass and glass SPG clipped to my left hip, wear a wrist computer and a self-winding watch and at least carry a mechanical (Bourdon-tube) depth gauge in a thigh pocket, if I don't wear it. Wearing two dive computers or bottom timers instead of the watch and mechanical gauge would also provide an acceptable level of redundancy.

For the OP, though, at his current level of experience, he probably doesn't need that much. I'd go with a brass and glass SPG on a 24" hose, and a wrist computer. I bought an ex-rental Suunto Favor on eBay for $70 a couple of years back, and have put about 200 dives on it with nary a problem. It's air-only so it somewhat limits me when I'm diving Nitrox; I would buy a computer that will do at least 21-50% Nitrox if you think you might go that way. And if you think you might ever get into technical diving, then I'd consider buying an Uwatec Aladin Tec 2G, a Dive Rite Nitek Duo (also sold as the Tusa IQ-700 and the Zeagle N2ition), or a Suunto Vytec/Vytec DS or Vyper/Vyper 2. You can find good deals on these used, and you can find the first two new from etailers for $300 or so. All except the Vyper and Vytec are two-gas nitrox computers with gauge modes. The Vyper is one-gas, the Vytecs are 3-gas (and wireless AI is available). The rest aren't AI, so if the OP's heart is set on that be prepared to spend 2 or 3 times as much. And all of the above models have bungied wrist mounts available for them from Deep Sea Supply; the bungie mount is usually lower profile than the OEM wrist mounts, is a lot more convenient to put on or take off when wearing thick gloves, and is depth compensating so you don't have adjust your strap as you change depth.

I have had two computers crap out on me, both involving the depth sensor (Suunto got a bad batch of sensors from a supplier a few years back). While I could certainly do an ascent without the depth gauge, I'd just as soon not have to terminate a dive when I have plenty of gas, and I like to be able to note the depth of points so I can find them again. Also, having a depth gauge makes doing a deep stop easier, if for some reason I don't want to deploy a DSMB on a marked line (under a heavy kelp canopy in surge, say).

Guy

 

[herman]

I am going to buck the trend a little. A full console, SPG/compass/depth gauge is not that much more bulky than just the SPG, a little but not that much unless you have one of the huge honkers from years ago. While I do like my computer on my wrist and I do find it more convenient I still prefer my compass to be on my console, mainly because I rarely need/use it and if it's not on the console I tend to not bother taking it. In addition, I like having a standard old depth gauge along just in case the computer dies, it takes up little space so why not. Mechanical gauges are really tough and rarely give problems so even for a new diver it's something that is not too much of a gamble to buy used ones fairly inexpensively off of ebay or even better a local place like Craig list- not something I suggest for regulators however. Even if you decide later you don't want it all in the console, you can buy wrist mounts for the compass and remove the console from the SPG. If at some point your computer dies, you stuff the SPG back in the console along with the depth gauge and keep diving (assuming you have a watch). You end up with the best of both worlds.

 

[herman]

I just happen to have an old computer so I strap it to me as a backup to my primary computer. I bought it back when simple dive computers were around $100. Or just get a capillary tube guage

and strap it to your wrist as a back up. You will also need a watch.

I have had one computer failure and it was after a dive that I noticed that teh computer was reading way off from the reading of my backup computer. Since I had both it was no big deal and the manufacturer replaced it at no cost.

Unfortunately, Trident had stopped making these.

 

[rrweather]

My first computer purchase was a cobra 2, which is air integrated with a hose. It was a good computer. Ultimately I sold it because I didn't like looking down all the time to see my depth. On shallower dives, I don't worry about my air as much so I don't need the air pressure in front of me at all times. After doing a couple of night dives, this became more of an issue. I just got tired of looking down so see my depth and dive time.

I am also going to start diving doubles at some point and a simple SPG is pretty much the way of the world when it comes to doubles. A wrist mounted computer allows my gear to be set up the same whether diving doubles or singles. This will help me reinforce the motions no matter what I dive.

I picked up a used Nitek Duo here on SB for less than $200. Couple that with a brass and glass SPG with a hose for less than $80 and I have a nice setup. I was able to sell the Cobra for the cost of the Duo and the SPG and then some. Had I not purchased the cobra originally, I could have come out having spent less. Then again, half of the experience of diving is finding what equipment works best for you. If you can find a dive buddy or a shop that will let you try a computer, try a wrist mounted version and a console version. See what works best for you. I haven't met a person yet that bought a wrist mount computer only to wish they had bought a console or console computer. If you can manage to find a used computer and SPG for less than a new console, I wouldn't think twice about the decision. Even if you want the full console, post a wanted ad for one. I wouldn't buy one for full price. Anything you can get used will be easier for you to swallow if you decide to replace it in a year or two.

 

[Amphibious]

like other posters I'm a huge fan of a simple SPG & a wrist mounted computer (Suunto Vyper)

I've never had a computer crash on me during a dive, but if I did, I would abort the dive and make a safe slow assent (you don't need a Depth Gauge for this)

 

[Sinbad the Diver]

like other posters I'm a huge fan of a simple SPG & a wrist mounted computer (Suunto Vyper)

I've never had a computer crash on me during a dive, but if I did, I would abort the dive and make a safe slow assent (you don't need a Depth Gauge for this)

Need....no, but I'd rather make my ascent with a depth gauge than without..I've been in quaries before where without a gauge you have no idea if you are going up or down, one of those why not have it items in my book.

 

[Amphibious]

Need....no, but I'd rather make my ascent with a depth gauge than without..I've been in quarries before where without a gauge you have no idea if you are going up or down, one of those why not have it items in my book.

you have some fancy bubble-less exhaust system on your second stage?

always have the option of shooting a bag for a mid-water assent...

 

[herman]

like other posters I'm a huge fan of a simple SPG & a wrist mounted computer (Suunto Vyper)

I've never had a computer crash on me during a dive, but if I did, I would abort the dive and make a safe slow assent (you don't need a Depth Gauge for this)

I have had 2 die and another that batteries came close to going. With a depth gauge, knowledge of the tables and a watch there is no need to abort the dive or diving the rest of the day (or trip in one case).

 

[Amphibious]

if your computer fails because the batt goes dead it's your fault. I swap mine out when ever I catch them even close to low.

over 1500hrs + (very conservative estimation) of Scuba and Freediving on 3 computers (Cobra, Vyper, & D3) and never a hiccup. I'll take those odds.

 

[GrumpyOldGuy]

I have had 2 die and another that batteries came close to going. With a depth gauge, knowledge of the tables and a watch there is no need to abort the dive or diving the rest of the day (or trip in one case).

I agree, if you can't check the batteries, you should not be using a DC. Maybe you had some other issue that you have not disclosed why the batteries died. It is like running out of gas, in your car or on your dive... generally a lame excuse.

Seriously, on the third dive of the day and your computer dives midway through the dive, are you telling me you have the time and data handy to manually calculate your NDL's for all 3 dives while submerged? If you can and get the right answer, I am totally impressed. I could run the numbers for sure, not so sure the answer would be right (I know my limits, tables are top side only for me).

A question though. If you are using a DC, which will tend to give you a lot more bottom time on repetitive dives and then you do your table thing since the battery died and find predictably that the tables indicated you have deco time that you have blown past, what do you do?

I have always followed the ideal that if you are going to dive a DC, you dive the DC. If you need redundancy, then dive with a buddy or buy a 2nd one. If you want to dive tables (and there are good reasons for some divers and dive profiles), then dive tables. Both work, I am not advocating either one is bad, but mixing them is difficult and unproductive.