Why NOT DIR?

[Dan Gibson]

You are making the assumption that someone would actually use a 12# plate with 121s. Who is doing this?

Worst possible case is perhaps a pair of LP8-121 overfilled to 3500PSI. Each tank is thus about 12 lbs negative when full and pretty close to neutral on stop at that end of the dive. So a set of doubles is 24 lbs negative (this diver’s nuts, so add two can lights, for 4 more lbs) and let’s round up a plastic backplate rig to 30 lbs negative at the start of the dive.

At the end of the dive, after your buddy has had catastrophic failure of both his regs right when you hit Bingo Air, and you’ve both emptied the two LP8-121s getting out and making your stops, the rig is neutral.

Now since you’re diving into an ice cave in the arctic you’ve to on a drysuit and 400 weight jimmies. Since you’re 6’4” and run 17 stone, even “shrink wrapped with a squirt” you’re wearing a 30 lb weightbelt (rubber with wire bail buckle, of course).

Works for me … keep the suit right at even “shrink wrapped with a squirt,” trim the rest with the wings, that’s about as close as you’ll be able to get in a worst possible case.

But add a 12 lb backplate and put 8 lbs on the rig and just wear a 10 lb weight belt? I can’t see it.

 

[Thalassamania]

You are making the assumption that someone would actually use a 12# plate with 121s. Who is doing this?

Please be so good as to actualy read the post before you type.

Worst possible case is perhaps a pair of LP8-121 overfilled to 3500PS.

 

[underwasser bolt]

move another thread you did not like did you? seems to me it was concerning DIR philosophy, just not part of philosophy DIR approves of. too much "correct thinking" needed in DIR;

 

[limeyx]

Worst possible case is perhaps a pair of LP8-121 overfilled to 3500PSI. Each tank is thus about 12 lbs negative when full and pretty close to neutral on stop at that end of the dive. So a set of doubles is 24 lbs negative (this diver’s nuts, so add two can lights, for 4 more lbs) and let’s round up a plastic backplate rig to 30 lbs negative at the start of the dive.
...

But add a 12 lb backplate and put 8 lbs on the rig and just wear a 10 lb weight belt? I can’t see it.

GUE (at least in my training) generally recommends that the diver remain with their tanks while on SCUBA. So unless you are planning on doing a bit of freediving at the end of the dive, or needing to get out of your gear, I really dont see why you need to have the diver neutral.

In fact, for a lot of diving, I would want the diver to be somewhat positive, as the one place I can really see needing to ditch a rig is on the surface, and I darn well want to make sure I float and not sink.

 

[Thalassamania]

GUE (at least in my training) generally recommends that the diver remain with their tanks while on SCUBA. So unless you are planning on doing a bit of freediving at the end of the dive, or needing to get out of your gear, I really dont see why you need to have the diver neutral.

In fact, for a lot of diving, I would want the diver to be somewhat positive, as the one place I can really see needing to ditch a rig is on the surface, and I darn well want to make sure I float and not sink.

In this entire conversation no one has ever advocated ditching a rig underwater, what one earth is that all about?

 

[Dan Gibson]

I did and your example sucked. A 30# belt falls in HFS territory and is dangerous to have as a single source of ditachable weight.

When I use 400 gram thinsulate under my TLS, I myself come in around 19# buoyant. My PST 104s with 2# AL plate filled to 3600psi makes my rig come in around 30# negative (weighed with fish scale for confirmation). The swing is around #22 from 3600 to empty.

Rig -30
Diver +19
Start dive -11
End dive+11

btw, I can swim the -11 at start without belt and can light, but it is on the limit of comfortable so maybe I need to become a HFS.

I add a weight belt and can light (several different combinations I might add) to make sure I can stay down with empty tanks which are also independently ditachable at any point in the dive. I do not put a 12# plate on which is not ditchable not to mention I would be so head heavy to make the dive unenjoyable.

I can also choose several different setup and gas volumes for different dives. None of which would ever include a 12# plate.

You cited earlier that a heavy backplate was a DIR concept and that is pure BS.

Please be so good as to actualy read the post before you type.

 

[Dan Gibson]

Maybe suggesting both the rig and diver be independently neutral implies this conclusion. I diver can be close to neutral, but the rig cannot since there is a swing in buoyancy. The rig might balance out at some point during the dive, but it can't at both the begining and end.

In this entire conversation no one has ever advocated ditching a rig underwater, what one earth is that all about?

 

[Doc Intrepid]

I can also choose several different setup and gas volumes for different dives. None of which would ever include a 12# plate.

You cited earlier that a heavy backplate was a DIR concept and that is pure BS.

Dan,

I'm not saying anything about what Thal did or didn't say. I AM saying I didn't see any "citation" of some authoratative source.

I wear a 12 lb backplate with double PST 130s and a DUI450 when I'm diving very cold ocean in the PNW wearing a Weezle Extreme+ undergarment. I wear a 6 lb backplate with the same tanks and suit but a polarfleece undergarment in the warmer ocean on the Atlantic coast.

I do this because it balances me out perfectly. I have worked in this set up with not one or two, but three GUE instructors, all of whom have had no overt qualms about my balance. They moved weights and plates around for other students, but in this particular rig and given my characteristics, its an optimal set up for me. I don't dive with ditchable weight nor, obviously, a V-weight.

The only "DIR concept" that I'm able to cite is JJ's textbook and some of George's posts, and they don't say anything about a 12 lb plate; but they DO emphasize the importance of being perfectly weighted with (near) empty doubles (empty argon bottle, 2 empty 40s, Gavin, etc.). Unless I'm mistaken, that's the concept that may have been referred to earlier.

YMMV.

 

[Kingpatzer]

Poster A says "I don't like DIR because of x, y and z" where x, y, and z have nothing to do with DIR.

It demonstrates a lack on knowledge of DIR by the poster.

Which is why _I_ don't diver DIR.

Not that DIR may or may not be a worthwhile way of diving.

But I never see a discussion about DIR where DIR people don't start arguing about what is and isn't DIR, and at the same time telling all the non-DIR people that what they are doing is or isn't safe while commenting on how the non-DIR folks don't really understand DIR and if they would just take the right courses they'd be enlightened.

I dive because I want to dive, not because i want to join some partisan camp, for or against something.

Those who think it's a good idea to call their method of diving "Doing it Right" in [SIZE=-1]opposition[/SIZE] to everyone else's method of diving (who by extension must be doing it wrong) tells me what I need to know most -- will the time and investment increase my fun? It's obvious it won't . . . judgmental philosophical jingoists are never fun.

 

[JeffG]

Which is why _I_ don't diver DIR.

Not that DIR may or may not be a worthwhile way of diving.

But I never see a discussion about DIR where DIR people don't start arguing about what is and isn't DIR, and at the same time telling all the non-DIR people that what they are doing is or isn't safe.

I dive because I want to dive, not because i want to join some partisan camp, for or against something.

Those who think it's a good idea to call their method of diving "Doing it Right" in [SIZE=-1]opposition[/SIZE] to everyone else's method of diving (who by extension must be doing it wrong) tells me what I need to know most -- will the time and investment increase my fun? It's obvious it won't . . . judgmental philosophical jingoists are never fun.

So before you know anything about something, you will automatically discount it.

Interesting Philosophy