Tank height strap for backplate?

[Lorenzoid]

Perhaps BC construction has changed over time but the BCs I am familiar with don't have a lot of flexibility. The cam straps are run through a hard plastic backplate. The plastic may flex a bit but not by much. I doubt it is very compressable. My old Beuchat BC was assembled this way as well as the Scubapro BCs I learned on. Most of the others I have seen look to be assembled the same way.

My guess is that on some jacket BCs, the plastic plate/frame has just enough "give"--probably imperceptible to the eye--that it's sufficient to absorb the energy we're talking about here, and that on other jacket BCs, there may be a very rigid plate/frame but the manufacturer includes camband pads. Before I switched to a BP/W, I had a couple of jackets, and I think one (Zeagle) was like the former and the other (Aeris) was like the latter. Anyway, these are just my theories. It would be useful if Tobin would chime in and explain the rationale for the wedge blocks.

 

[stuartv]

you have your own tanks don't you? Just wet them and set them the night before.... take them off and you're good to go

If you're talking to me, I do have one tank now. The deal on the double Genesis 100s disappeared before I could get to them.

Anyway, my experience so far has been with flying to a destination and diving with their tanks, so that's really more where I'm coming from. But, given my other recent experience of getting a pinch flat in my wing, I'm not sure I really want to attach my rig the night before and then transport it that way.

Oh, and I also just read a general rule, on the GUE website, I think, that said wetsuit divers should use AL tanks and dry suit divers should use steel. I do not anticipate affording a dry suit any time soon, and I do anticipate diving in water cold enough to wear a 7mm, so I'm actually wondering now if I shouldn't just focus on getting some AL80s, instead of trying to get more HP100s.

 

[tbone1004]

that gue recommendation is primarily for doubles usage. There is a difference in diving a set of double LP104's that are 3.3lbs negative each and with bands and manifold push 15lbs negative when they're empty, and a single HP100 that is about 3lbs negative with a valve. 15lbs negative is more than quite a few wetsuits in total buoyancy so it creates an unbalanced rig which is dangerous. There's also a big difference in neutrally buoyant Faber 85's and HP100's depending on how much wetsuit you are wearing.

I dive with a lot of GUE guys on a semi regular basis and I have yet to see one use a single AL80 unless they are in a place where steel isn't available, or are diving without a wetsuit at all and at that point the weight of the plate+sta+ss cam bands *around 10lbs negative* is enough to offset the aluminum tank and provide sufficient ballast to get a balanced rig. If you are using lead in addition to steel tanks, there is no reason to go to aluminum because then you are just adding more lead onto your rig.

don't drink koolaid, think about the rationale about why those guidelines are there, and they will make more sense

 

[stuartv]

don't drink koolaid, think about the rationale about why those guidelines are there, and they will make more sense

I don't think I was drinking Kool-aid. It was that page plus, actually, a YT vid someone linked to yesterday about diving to 27m in a 7mm wetsuit. The video was used to illustrate how negative you can be and what a problem that can be if you go that deep in a 7mm and have a catastrophic BC failure. And, yes, I remember what you've said before about how unlikely it is to end up being able to get NO lift from a blown BC. I just like to evaluate worst-case scenarios. Anyway, going "deep" in 7mm seems like it has its drawbacks, so then I thought that going with an even heavier tank might just make it worse IF a worst-case scenario happened.

But, as you say, I believe I will still have lead on, even with a steel tank. I'm guessing (roughly) I'll have BP + 14# ballast to dive a 7mm suit with an AL80. I haven't actually tried it yet. So, swapping to an HP100 means I'll still have somewhere around 7 or 8 # ballast, right? So, for singles I guess AL versus steel maybe doesn't matter - but I still need to consider diving deep in a 7mm.

I'll be asking my Deep instructor about that in class this weekend.

 

[eelnoraa]

Oh, and I also just read a general rule, on the GUE website, I think, that said wetsuit divers should use AL tanks and dry suit divers should use steel. I do not anticipate affording a dry suit any time soon, and I do anticipate diving in water cold enough to wear a 7mm, so I'm actually wondering now if I shouldn't just focus on getting some AL80s, instead of trying to get more HP100s.

Wait, you didn't read the GUE general rule correctly. The proper choice of appropriate tanks are to archive "balanced rig". And usually, drysuit + Steel vs wetsuit + AL80 are what balanced rig ended up with for double setup. It is not a rule. The rule is, once again, to have balanced rig.

For single tank, I don't see drysuit + steel vs wetsuit + AL80 being the necessary case. I can easily have balanced rig with wetsuit and single HP100.

 

[Lorenzoid]

If one is really concerned about wing failure at depth with a steel tank and a wetsuit, consider taking a lift bag.

 

[ams511]

Wait, you didn't read the GUE general rule correctly.

He probably did. I received the same impression when I read the fundies book. I am not sure that the HP 80, 100, and 117 were out at the time the book was written. I am sure that when you take the class they explain this more in depth and give updates. The websites that post the info still have old information.

---------- Post added March 26th, 2015 at 02:26 PM ----------

I don't think I was drinking Kool-aid. It was that page plus, actually, a YT vid someone linked to yesterday about diving to 27m in a 7mm wetsuit. The video was used to illustrate how negative you can be and what a problem that can be if you go that deep in a 7mm and have a catastrophic BC failure. And, yes, I remember what you've said before about how unlikely it is to end up being able to get NO lift from a blown BC. I just like to evaluate worst-case scenarios.

The basic rule of thumb used to be that a person should have no difficulty in swimming up 10 to 12 lbs with no air in a BC. Of course this varies by individual. On a deep dive with a wetsuit your suit will lose most of its buoyancy, so if you have a wing failure then you need to have enough ditchable weight that you can drop to swim up your rig. So you don't want to have all you weight consisting of your tank, plate, reg, and DSS plate weights because you will have no weight to drop.

 

[Dhboner]

And that's why I have a big-ass SMB

 

[Nemrod]

I installed a strap on all of my plates. I put it under a sexbolt. Mine has a plastic buckle just like the poodle jackets. Hey, even poodle jackets have some good ideas on occasion . I have it set to the correct height for the tanks I use and it is adjustable. I bought the straps at a backpacking store, cut off what I did not need and melted a hole with a soldering iron through the strap forming a loop. Looks exactly like the ones on a poodle jacket and works as well or better.

The primary purpose for the strap on a poodle jacket is to assist attaching the jacket to the tank with the integrated weight and trim pockets. Even with the integrated weight out of the BC the trim pockets often have weight which causes quite a fuss sometimes. Plus, as noted, it helps to prevent the tank valve from rotating far away from the divers body under certain conditions.

My warm water rigs are optional weight integrated but of course do have two cambands and the hang strap. And no, sorry, it is not going to tangle on anything.

N

 

[scubafanatic]

A while back (few yrs ago) I was in tough with ScottZeagle (Zeagle rep here on scubaboard)

part # for Ranger tank height adjustment strap.

The part number for those is 7284.

I have successfully used this strap on several different BCD and BP set ups.