Spg

Ok, so by now I'm probably annoying a fair amount of you with my posts. I've been off SB for a few months as most of my earlier questions have been answered. Unfortunately (for you) I am now looking at doing fundies in September and have a number of questions.

One of these is the location of the SPG and also the reference to it's storage in the JJ's Fundies book. It says something along the lines that the SPG should be clipped on left waist d-ring and accessible enough such that it can be viewed by unclipping it.

I'm pretty puzzled by this. I'm doing it, but I'm still pretty puzzled. It doesn't seem like a good solution.

I believe that an SPG should be viewable simply by glancing down. It should not require an activity such as unclipping for it to be readable. Such an activity creates an obstacle to viewing at any time how much gas you have remaining. This doesn't seem like a good idea and smacks to me of complacency.

So what am I not getting???

Cheers,
J

The SPG is really a secondary device--you'll be keeping track of your depth and time, which will imply your gas usage. You'll be occasionally unclipping your SPG and checking it, but not needing to look at it every minute or so.

InTheDrink:

Ok, so by now I'm probably annoying a fair amount of you with my posts. I've been off SB for a few months as most of my earlier questions have been answered. Unfortunately (for you) I am now looking at doing fundies in September and have a number of questions.

One of these is the location of the SPG and also the reference to it's storage in the JJ's Fundies book. It says something along the lines that the SPG should be clipped on left waist d-ring and accessible enough such that it can be viewed by unclipping it.

I'm pretty puzzled by this. I'm doing it, but I'm still pretty puzzled. It doesn't seem like a good solution.

I believe that an SPG should be viewable simply by glancing down. It should not require an activity such as unclipping for it to be readable. Such an activity creates an obstacle to viewing at any time how much gas you have remaining. This doesn't seem like a good idea and smacks to me of complacency.

So what am I not getting???

Cheers,
J

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No expert but my understanding is that the SPG is really a backup/confirmation to your brain. You know what your SAC ranges, how deep you are going (or how deep you are), and how long you've been down. From all that you should know how much gas you have left.

In addition you want to avoid cluttering things as much as possible, so putting it in a spot that you can glance and see would take up room from something else.

Honestly, it doesn't take much practice to get used to unclipping and checking. The hard part for me has been reclipping it.

Later on, you might progress to diving with stages or deco bottles, as well. Having the spg on the hip keeps it out of the way and reduces confusion between it and the SPGs on your stage/deco bottles.

InTheDrink:

I believe that an SPG should be viewable simply by glancing down. It should not require an activity such as unclipping for it to be readable. Such an activity creates an obstacle to viewing at any time how much gas you have remaining. This doesn't seem like a good idea and smacks to me of complacency.

So what am I not getting???

Cheers,
J

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This is the first impulse and best instinct of a rational person. Being able to use the equipment. An SPG was decided as necessary many years ago. Any other solution is over complicated and rendered useless. It should be in front where it can be seen.

vintagediver:

This is the first impulse and best instinct of a rational person. Being able to use the equipment. An SPG was decided as necessary many years ago. Any other solution is over complicated and rendered useless. It should be in front where it can be seen.

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Might want to recheck the forum you are in.

mikemill:

Might want to recheck the forum you are in.

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That's an interesting point you make. Does DIR not tolerate questions about its own choices? This would be a big turn off for me. If you can't defend a position on its merits but need to rely on the organisation infallibility you're in real dangerous territory. Trust me, I grew up in Catholic Ireland and I saw exactly where the infallibility of the church took us.

Anyhow, I'm hoping (and pretty sure) that DIR embraces questions. Cos I got a lot of them

My worry, from the other posts, about an SPG being a backup, is that this factors in various subjective assumptions that will be right most of the time but not all of the time. You could easily equate this to "same day same ocean"-think. Yeah, in most cases it's fine, but there are plenty when it's not. What if you have a leak, in really poor viz. You are working on the basis of a missing variable. You are working on what you believe should be true, not what is true. Hmmm.

I can understand that keeping it to the side is less cluttered and with other gear on board this may well make sense. This would be the kind of explanation I am looking for.

Can anyone explain to me why having the SPG attached to the left hip d-ring on a bungee wouldn't be a better solution? Then one could simply pull and see, rather than unclip/reclip. I understand that unclipping/reclipping isn't hard so please don't tell me that. Pulling a bungee is smaller obstacle than un/re-clipping.

J

This is like so many other facets of GUE/DIR diving. If you look at the WHOLE picture, the details make much better sense.

When you start with careful gas planning based on good information on past dives, and adequate emergency reserves, the SPG becomes more of a convenience than a necessity (assuming you actually CHECK your tanks before you dive them, I will add before somebody else does). An aware diver should be able to tell you how much gas he has at any given time without looking at the gauge. So putting it in a place where it IS accessible but interferes with nothing else is quite reasonable.

For a brand new diver who blows through gas and has no idea how fast it will go, making the gauge more easily accessible might be reasonable. We have put SPGs on retractors for our OW students for that reason.

Edited to add: Mikemill's comment referred to the fact that the DIR forum is a place where people should get DIR answers to their questions. The reason for this is that, when such questions were asked in open forums, people got into squabbles about whether DIR was reasonable or not. If you really want to talk about the various options available for a given thing, this is not the forum to do that in, but there are others. Here, you should get the DIR answer, and with a good explanation of why, so long as you are not perceived as trolling.

InTheDrink:

That's an interesting point you make. Does DIR not tolerate questions about its own choices? This would be a big turn off for me. If you can't defend a position on its merits but need to rely on the organisation infallibility you're in real dangerous territory. Trust me, I grew up in Catholic Ireland and I saw exactly where the infallibility of the church took us.

Anyhow, I'm hoping (and pretty sure) that DIR embraces questions. Cos I got a lot of them

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You can ask all the question you want. This forum does have the rule that answers should be in line with the DIR philosophy.

My worry, from the other posts, about an SPG being a backup, is that this factors in various subjective assumptions that will be right most of the time but not all of the time. You could easily equate this to "same day same ocean"-think. Yeah, in most cases it's fine, but there are plenty when it's not. What if you have a leak, in really poor viz. You are working on the basis of a missing variable. You are working on what you believe should be true, not what is true. Hmmm.

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Lets say you had a small leak (and none of your buddies noticed). When you did check your SPG at say 10 minutes you'll notice you have less than expected gas. At this point you start doing down the list of reasons for it. Perhaps you check it again at 15 minutes and you see you are going through it faster than expected. At this point you thumb it, ask for help, etc.

I can understand that keeping it to the side is less cluttered and with other gear on board this may well make sense. This would be the kind of explanation I am looking for.

Can anyone explain to me why having the SPG attached to the left hip d-ring on a bungee wouldn't be a better solution? Then one could simply pull and see, rather than unclip/reclip. I understand that unclipping/reclipping isn't hard so please don't tell me that. Pulling a bungee is smaller obstacle than un/re-clipping.

J

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Retractors get jammed. A bungee, I have trouble envisioning how I'd rig a bungee so that it was nice and tight (and out of the way) when I'm not looking at it but still long enough to get it up to my face (or well near it anyhow), around any bottles (without snagging on anything), without snapping back due to the high spring constant.

TSandM:

This is like so many other facets of GUE/DIR diving. If you look at the WHOLE picture, the details make much better sense.

When you start with careful gas planning based on good information on past dives, and adequate emergency reserves, the SPG becomes more of a convenience than a necessity (assuming you actually CHECK your tanks before you dive them, I will add before somebody else does). An aware diver should be able to tell you how much gas he has at any given time without looking at the gauge. So putting it in a place where it IS accessible but interferes with nothing else is quite reasonable.

For a brand new diver who blows through gas and has no idea how fast it will go, making the gauge more easily accessible might be reasonable. We have put SPGs on retractors for our OW students for that reason.

Edited to add: Mikemill's comment referred to the fact that the DIR forum is a place where people should get DIR answers to their questions. The reason for this is that, when such questions were asked in open forums, people got into squabbles about whether DIR was reasonable or not. If you really want to talk about the various options available for a given thing, this is not the forum to do that in, but there are others. Here, you should get the DIR answer, and with a good explanation of why, so long as you are not perceived as trolling.

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Thanks Lynne, good explanation of the larger picture.

I had a dive in Jan where I ended up on 7 bar. It was a shallow muck dive. I had done 4 or 5 dives at the same site for same dive time and came up with 70 or 80 bar. I've still no idea why. Everyone else came up with loads. Because I know how much air I use I wasn't checking my SPG all that regularly (complacency) and I wasn't deep so wasn't being particularly attentive. Still no idea what happened. I didn't feel my SCR raising in any discernible way. Guess it can just happen sometimes.

So, to be clear, is an extensible SPG compliant or not?

Cheers,
J