What was I thinking (Single tank BP/Wing, SS)?

[bradlw]

OK, so back around 24 years ago, I was just coming out of a lot of tech dive training, diving doubles, etc...
And I was liking the BP/Wing and long house set-up
This was before BP and wings were mainstream for recreational diving

I decided to buy a single tank set-up
ended up with one from Halcyon. Basically, this of very similar (Eclipse™ BC System)
I went with the SS backplate thinking that I could eliminate or at least greatly reduce the lead coming along for the ride.

I only ended up diving the thing a couple fo times, then life got in the way of diving and it's been in storage since.

It's still in really great shape. I replaced the LPI and the OPV valve, and I'm using it to get back into diving.

I don't think that I ever really had this rig dialed in, and whatever I had figured out is long gone from memory.
So now as I'm getting back up to speed generally, I'm also trying to figure out what was I thinking when buying this and what was I thinking the strategy was going to be to dial it in.

So with my DSMB and spool mounted, this thing weighs-in at 13.44# dry
-4.65# submerged in a saltwater pool...so basically fresh water)

with no wetsuit or with my 2mm rashguard, no lead needed in freshwater (700 psi AL80, and I repeated the test with a diff AL80 down to about 400PSI)
It's actually a pretty great set-up in that regard for an AL80 I think. Just slightly negative and no problem at all to kick up, The negative is that it's back heavy so trim is difficult.

So should I just plan on carrying maybe 4 to 6 pounds of lead on the waist?

With a 3mm farmer john and jacket wetsuit I needed about 4 to 6 pounds (I'm thinking 5 would probably be about right)

So not bad I think

But

Now I'm thinking about breaking apart my double set since I'll most likely never want to dive that again. Research suggests that these are PST 100,
-8.8 full, and -1.3 empty.
So I'm thinking full tanks will be on the heavy side and will certainly be back heavy.

Can you think of a strategy that I might have had in mind 24 years ago?

Should I switch the baby bladder over to my old aluminum BP used for doubles? (probably Dive Rite, I have no memory of what it was)

 

[inquis]

No one can answer these for you, because there are so many combinations and possibilities. This must be evaluated on a case-by-case basis within YOUR priorities (which we don't know). For example, are you trying to do everything with a single setup?

One bottom line is if you are not neutral with a nearly empty tank/wing, you should drop weight. Yes, this could be done by swapping an AL plate for a steel.

Another is that if you rotate from horizontal when you stop kicking, then you should redistribute weight. If you don't have any lead to move, then switch to the AL plate or AL tanks (or maybe both).

Of the two, I'd prioritize trim and just live with being slightly heavier than desired.

 

[Badger7]

Personally, I'd want a little lead to drop anyway when diving a wetsuit to establish extra bouyancy at the surface in the case of a bladder failure with a full tank of gas. If a perfectly balanced rig with a wetsuit resulted in zero lead requirement, I'd probably swap the steel plate out for aluminum so I could carry a few pounds of droppable lead, thats always felt like a nice extra margin of safety. Without the extra safety margin of drysuit bouyancy, wetsuit with a few pounds of lead I can chuck is my choice.

 

[bradlw]

No one can answer these for you,

of course.... I'm just asking for your speculation about what I might have been thinking of then...as an active and proficient diver, that is just not coming to this old and very rusty diver?

or maybe to rephrase.... From YOUR perspective as an active and proficient diver, what is this SS set-up good for?...or what was Halcyon thinking?

Personally, I'd want a little lead to drop anyway when diving a wetsuit to establish extra bouyancy at the surface in the case of a bladder failure with a full tank of gas. If a perfectly balanced rig with a wetsuit resulted in zero lead requirement, I'd probably swap the steel plate out for aluminum so I could carry a few pounds of droppable lead, thats always felt like a nice extra margin of safety. Without the extra safety margin of drysuit bouyancy, wetsuit with a few pounds of lead I can chuck is my choice.

Yeah, I get that for sure....and that's the root of my question here....and is probably pointing to my answer. This SS BP might be ideal only for wetsuit diving.

As I'm writing this though, I have a thought coming to mind...that might be a memory of what I was thinking through way back then. I just have a feeling that I had not fully developed the thought and plan, though....

With this harness and BP, I bought the backplate back pad/pocket thing and a large marker bouy that stows inside. It doubles as a lift bag. The one they sell today that's similar or the same as what I have is 40# lift.
Maybe I was thinking that if I'm close to neutral that's where I'd want to be to kick up a normal ascent anyway...neutral or slightly negative
and then once on the surface, my DSMB becomes a pool noodle

If I run with that idea, then maybe this set-up is ok for no wetsuit, as long as I'm diving AL80's

anyway, it seems to be not so good for use with my HP steel tanks, wetsuit or not.
I suppose that I could still use the lift bag as an emergency BC, but that falls apart if I was on a wall for example... and sinking with a blown BC bladder while I'm trying to get the lift bag out and set-up for use.

 

[inquis]

what is this SS set-up good for?

It would be perfect for me in a 3mm with AL80 tank. My normal is 4 lbs in trim pockets with an AL plate in that config (fresh water). For ocean diving, I'd add a pair of 3 lb bricks to waist-mounted trim pockets. I don't ever dive without a wetsuit, even in 82° F (28° C) water. (Bumps on the ladder or rocks on the shore, invisible stinging thingies, and just the cumulative thermal nature of multiple dives over several days.)

 

[Divin'Papaw]

I have 4 Worthington steel HP 100s that are even more negative than the PSTs. Worthingtons are -10 full, -2.5 empty. I dive them with a 5# plate and an STA (~2#) in my 2.5mm summer wetsuit in salt water. I am ~ 2-3# overweighted, but it's not enough to be an issue. I have no problem being comfortable and in trim throughout the dive.