Which has a higher rate of failure a SPG or a transmitter?

[Mayor]

Really? We have to ask this question? This bag full of money sitting right by my desk said put it all on the SPG!

 

[GrumpyOldGuy]

In all fairness, I suspect the failure modes of AI vs SPG are different and a simple analysis of failure rate is not as helpful as one would think.
- AI is probably prone more to total catastrophic failures (flood, battery, electronics) and aggravating link issues which are clearly apparent.
- SPG can have leaks and and drift a bit (which also are apparent and can often be tolerated short term), worst case though is a sticky needle, which could lead to OOA (although its very rare)

Both fail you if you don't bother looking at them and turn off your brain.

FYI: I dive an SPG cause I am a cheap bastard!

 

[Hatul]

Can you tell me how your computer knows what tank size you are using? For instance I will often switch from double HP100's to a single HP130 and my min gas changes. If I travel to the tropics and am using an AL80 it again changes. Do you go into the software and change the tank size every time you change tank configuration? Have you hand calculated it out to better understand what the computer is telling you?

Good question. This also struck me when I got the Galileo Sol--how does it know how much air I have left?

The answer is it doesn't. The computer does not know the size of the tank or anything about volume of air remaining or consumed. All it knows is the psi/min consumption and your depth. It also knows your current pressure and that the reserve pressure (usually set around 500 psi) means out of air. From that it can computer the SAC in psi/min and the psi required to make the safety stop, any deco stops and the ascent. It can also compute how many minutes you have at the current depth (Remaining Bottom Time). Note that it's all a calculation based on psi not on volume.

Back on land if you put in the size of your tank into the Smart Trac software, it can convert the SAC from psi/min to cu.ft/min.

 

[DaleC]

Your missing the point. Talking about what one needs in a discussion of a hobby is silly. None of us need to dive, but it was a silly statement too. Do you have gear you don't need? Gear that is beyond the basic gear, my bet would be yes. You don't need any more than a standard SPG, depth gauge, and compass and go dive. So talking about what someone "needs" is a ridiculous premise to start with.

So it comes down to what makes the dive more enjoyable for each diver. If you don't want that extra stuff, then so be it, if someone else does, so be it. I don't dive with a SPG attached as a back up, I use a wireless AI wrist computer. If you want to have that extra piece of equipment, more power to you but to say it's a need thing is different also. Then to say that the benifits of those things don't offer anyone additional safety is along those same lines

It's typical of many SB discussion where someone comes in and says someone else is lacking, or as you state, "Skills deficit" because they choose to use different equipment. I don't buy it and I think that is a little snobbish of an arguement.

For reference I learned to dive in 1983, only analog gauges available and the Navy Dive Tables, no rec tables. I feel totally comfortable diving that way and had no issues. Now I choose to dive with the new stuff, not because I need to because of some lack of training but because I enjoy it that way.

Why you feel that distinguishing between what is "needed" to dive and what is "wanted" to dive is silly or ridiculous is beyond me. How do you make any sort of intelligent decisions that way? There are certain skills and pieces of equipment one needs to dive, and some skills and pieces of equipment one may want (to enhance ones own experience in some sort of way). Let's hope we can discuss which is which. You seem to feel that my suggesting an AI computer is a want instead of a need is an insult - It is not. It's just a fact. Perhaps you feel the need to justify such a large expenditure so it irks you to hear it refered to as a want?

I dive with a lot of wants because I enjoy them. I have about 20 pairs of fins and 30 masks and a whole garage full of crap- who cares.

As for the additional safety aspect: Saying one is liable to forget to check their SPG so having a $1000 AIC adds safety just doesn't cut it with me. Isn't the person who forgets to check one just as likely to forget the other? And there's nothing that AIC is going to display that makes one safer on a recreational dive that a less expensive array + some basic diving skill won't.
If one is good at checking gauges and understands the background theory then an AIC is just another choice of equipment, albeit an expensive one. If one lacks awareness or the theoretical basis for computing those values, then an AIC is an equipment solution to a skills deficit. Wrong?

 

[endurodog]

Why you feel that distinguishing between what is "needed" to dive and what is "wanted" to dive is silly or ridiculous is beyond me. How do you make any sort of intelligent decisions that way? There are certain skills and pieces of equipment one needs to dive, and some skills and pieces of equipment one may want (to enhance ones own experience in some sort of way). Let's hope we can discuss which is which. You seem to feel that my suggesting an AI computer is a want instead of a need is an insult - .

Dale you just don't get it, it's your attitude and statements toward the issue. You talk about not being impressed with how much money someone has spent on a gadget, no one has asked you to be impressed. You talk about wants and needs like your defintion of those things matter more and that those that use it for safety are not properly trained.

But the big point is talking about what is needed and not and you don't seem to get it, nothing is needed in a hobby. How someone choses to enjoy that hobby as long as it's not unsafe or effecting you is up to that person. There is no need to talk down to them about things that are not needed. There are pieces of gear that I don't use and don't have a desire to own but I'm not gonna say they are not needed. Again to act in that way is a form of being snobbish but those that are so set in that mind set just can't see past it. That is the reason as you state about distinguishing between need and want and that is exactly why you like to term it silly or ridiculous and it's beyond you. Talk about making intelligent decisions, sheeshhh .

Your right this technoolgy has never provided any additional safety to anyone. (sarcasm). No one has said that they forget to check their readouts, but I have said and will stick by that it is easier and check more often when it's on my wrist. I have dived both and I know, and yes I have dived both safetly. Have you dived with an AI wireless wrist computer?

Dale your not wanting to use the gear because you don't see it as needed or don't like the expense is a personal decision and I won't argue with your decisions to dive your gear, or talk down to you about your choices, but why have the attitude about those that choose the other method?

 

[Hatul]

Can you tell me how your computer knows what tank size you are using? For instance I will often switch from double HP100's to a single HP130 and my min gas changes. If I travel to the tropics and am using an AL80 it again changes. Do you go into the software and change the tank size every time you change tank configuration? Have you hand calculated it out to better understand what the computer is telling you?

Hi Peter, I asked the same question when I got the Sol. How does it know how much air is in the tank and how much is left? The answer is it doesn't and has no need for it. It only works with pressures and time.

It knows the current tank pressure and after a few minutes it knows your psi/min consumption, and since it knows your depth it can calculate your current SAC in psi/min. It also knows that at tank reserve (usually set around 500 psi) you're out. It works out the psi required to complete the safety stop and any deco and deep stops and the ascent. By subtracting the (reserve pressure + the psi required for the ascent and stops) from the current pressure it gets the excess pressure left, divides that by current psi/min at depth and that's the Remaining Bottom Time in minutes.

It never needs volumes. The nice thing is, it's constantly updating this like a spreadsheet as your consumption in psi/min and depth change.

When on land, you enter the tank size into SmartTrak software and only then can it compute your SAC in cu.ft/min. The tank size finally allows the software to convert from psi to cu.ft.

(Sorry about the duplicate post. I did not realize my first post went through and rewrote it)

 

[Hatul]

You think comparison to driving an auto is appropriate? In a car you are traveling at 50 to 100 feet per second. Approaching cars are closing at 100 to 200 fps. Diving is more like walking through your home in terms of reaction speeds. Do you walk into doorways often? Or do you use expensive technology to avoid such accidents?

I guess some folks may need the bells and whistles (and alarms) and you may be one.

I do dive a Scubapro Mk7 (honker) just for kicks at times. The honking has never been a surprise for me.

BTW, I have never incurred unplanned deco. I have never run out of gas. When I dive, I pay attention to those things that matter.

The point is we make mistakes in both activities though the mistakes are different. As far as the running out of gas analogy, it takes several hours of driving to empty a tank of gas, while a tank of air takes about half an hour to empty at depth. You have much more time to notice the gas tank emptying and to refill it, yet people run out of gas every day. Furthermore running out of gas in a car is not life threatening while running out of air is. In a car we have out gas gauge staring us in the face and it sets off a warning light when close to empty. In diving the SPG is out of the way, no warning light, an we actually have much less time to notice it getting empty, and the consequences deadly.

 

[Blue Sparkle]

I am curious - are the respective problem rates that you refer to absolute, or proportional? Obviously, if SPGs are used for 100% of dives by 90% of divers, compared to transmitters being used by 10% of divers (and possibly not for all of their dives), the absolute number of SPG problems would presumably be higher than for transmitters, even if SPGs and transmitters were, proportionally, equally reliable. Have your repair dept folks been able to quantify the denominators?

I had a similar thought earlier in the thread, and asked a question. I've partially quoted below, but essentially beaverdivers related that his shop sells 1000% more hoseless AI computers (if I've done my math right), and has done so for the past 15 years; yet his shop's repair department still sees more SPG's. I never would have guessed that.

I have a question for you: Have you sold equal numbers of both?

I ask because if there are 1000 SPG's out there, and 250 transmitters, then even if you have twice as many SPG's failing as transmitters, that would still be a higher failure rate for transmitters.

Without knowing the total numbers we can't tell, but I suspect there are (at this point) many, many more SPG's out there, so I don't see "more coming in with problems" necessarily being meaningful.

On the other hand, if you do have those numbers (and we are comparing the same number of each), but just didn't put them in your post, then could you? That would make it meaningful.

We have been using UWATEC Hoseless Air- Integrated Dive Computers ( HAIDC ) in our training for both students, DM & Instructors since the late 90's. We have sold HAIDC's 10 to 1 ( SPG ) for the last 15 years.

 

[beaverdivers]

Hi Peter, I asked the same question when I got the Sol. How does it know how much air is in the tank and how much is left? The answer is it doesn't and has no need for it. It only works with pressures and time.

It knows the current tank pressure and after a few minutes it knows your psi/min consumption, and since it knows your depth it can calculate your current SAC in psi/min. It also knows that at tank reserve (usually set around 500 psi) you're out. It works out the psi required to complete the safety stop and any deco and deep stops and the ascent. By subtracting the (reserve pressure + the psi required for the ascent and stops) from the current pressure it gets the excess pressure left, divides that by current psi/min at depth and that's the Remaining Bottom Time in minutes.

It never needs volumes. The nice thing is, it's constantly updating this like a spreadsheet as your consumption in psi/min and depth change.

When on land, you enter the tank size into SmartTrak software and only then can it compute your SAC in cu.ft/min. The tank size finally allows the software to convert from psi to cu.ft.

(Sorry about the duplicate post. I did not realize my first post went through and rewrote it)

It was worth posting twice!

We use the Remaining Bottom Time ( RBT ) in our beginning pool session to see how comfortable a NEVER EVER student is. Then we have them watch their RBT through out their training ( pool & OW ).

It is fun to see their faces when they see their RBT go from 30 mins. ( while they are swimming ) to 60 mins. ( while they are resting or doing a fin pivot ). You could use a SPG and a watch, but the Galileo is taking a sample every 4 sec.

After each dive we download & debrief from both the pool & OW.

A SPG can NOT do that!

We have been using this teaching method since the late 90's.

Now, the Galileo Sol enables us to incorporate the heart rate!

 

[redacted]

It was worth posting twice!

We use the Remaining Bottom Time ( RBT ) in our beginning pool session to see how comfortable a NEVER EVER student is. Then we have them watch their RBT through out their training ( pool & OW ).

It is fun to see their faces when they see their RBT go from 30 mins. ( while they are swimming ) to 60 mins. ( while they are resting or doing a fin pivot ). You could use a SPG and a watch, but the Galileo is taking a sample every 4 sec.

After each dive we download & debrief from both the pool & OW.

A SPG can NOT do that!

We have been using this teaching method since the late 90's.

Now, the Galileo Sol enables us to incorporate the heart rate!

So, if they hover and watch the pretty fishes knowing it is only a 10 minute swim back to the mooring and a 5 minute ascent and let their RBT drop to close to 15 minutes and then start swimming back; how big do their eyes get?

Just because they are bells and whistles does not mean you can't get in trouble if you don't fully understand how they work and how to use them.