Wing bladder size and suggestion for backplate/harness system

[inquis]

A 35 lb wing will not work with all ballast on the rig in your Scotland scenario.

 

[-JD-]

Thanks, I’m now looking into the Hollis ST35 which seems nice, do you have any experience with any of these?

I was mainly looking at the halcyon wings, that’s why I was considering 30 or 40.

Sorry, I don't.
I have:
HOG 32lb Singles (Warm-water singles)
Hollis SMS-100 40lb Dual-Bladder Hybrid BM-Single/Sidemount (Cold-water singles)
Dive Rite RecXT 40lb Dual-Bladder Hybrid BM Singles/Doubles (Warm-water doubles)
OxyCheq Vertex 57lb Dual-Bladder BM-Doubles (Cold-water doubles)

I heartily prefer a little extra buoyancy as a cushion. A few inches of float makes a difference in even light chop.

As you might guess, I am a bit of a redundancy freak, so all of my larger wings are Dual-Bladder. Only option new would be the Dive Rite Rec EXP or XT. They are wide but have an anti-taco clip available to help with singles.

If I was buying single bladder, new, now, for your situation, I would lean toward the Apeks WTX-40 for cold water use. Should be pretty available in Scotland.

ETA: another slim, single-tank, 40 would be the OxyCheq MachV 40: 18#, 30# and 40# Single Wings

My instructor used them for his rental fleet.

 

[Giovanni Giuriani]

Sorry, I don't.
I have:
HOG 32lb Singles (Warm-water singles)
Hollis SMS-100 40lb Dual-Bladder Hybrid BM-Single/Sidemount (Cold-water singles)
Dive Rite RecXT 40lb Dual-Bladder Hybrid BM Singles/Doubles (Warm-water doubles)
OxyCheq Vertex 57lb Dual-Bladder BM-Doubles (Cold-water doubles)

I heartily prefer a little extra buoyancy as a cushion. A few inches of float makes a difference in even light chop.

As you might guess, I am a bit of a redundancy freak, so all of my larger wings are Dual-Bladder. Only option new would be the Dive Rite Rec EXP or XT. They are wide but have an anti-taco clip available to help with singles.

If I was buying single bladder, new, now, for your situation, I would lean toward the Apeks WTX-40 for cold water use. Should be pretty available in Scotland.

ETA: another slim, single-tank, 40 would be the OxyCheq MachV 40: 18#, 30# and 40# Single Wings

My instructor used them for his rental fleet.

Thanks, I have also looked at the apeks wing, I was told though they don’t fold away very well because of the shape and so could be quite bulky for travel. If I was to go back to the 40 might go with the halcyon one.

 

[inquis]

another slim, single-tank, 40 would be the OxyCheq MachV 40: 18#, 30# and 40# Single Wings

That's a pretty streamlined 40 lb wing. I doubt the taco would be significant.

 

[-JD-]

Thanks, I have also looked at the apeks wing, I was told though they don’t fold away very well because of the shape and so could be quite bulky for travel. If I was to go back to the 40 might go with the halcyon one.

I doubt you are going to find a huge difference in travel bulk between any (single-bladder) singles bladder/shell-construction wing in 30-40lb range.

If you are looking for the ultimate in back-inflate compactness, something like a ScubaPro LiteHawk with a bladder-only (no-shell) design might work, but that is a minimalist back-inflate BC and is not "modular." Actually, I have been tempted to pick-up an old one (never should have sold my son's when he outgrew it) and pull the bladder off to modify for backplate mounting.

 

[Giovanni Giuriani]

A 35 lb wing will not work with all ballast on the rig in your Scotland scenario.

What if I moved 4kg to a belt and kept about 8kg on the rig? 35lb wing could be good then? I know maybe at that point a 30lb wing would also be enough but I’d rather also maybe not be at the edge of what the wing can take and have a little extra.

 

[inquis]

From what you've said, you can ballpark your drysuit buoyancy at about +28 lbs (assuming you are neutral at reserve air levels in an empty jacket BC). (This comes from -26 lb lead, -1 lb reserve air, -0.5 lb empty 12 l cylinder, -2 lb regulator, +2 lb guess at an empty BC.)

I must apologize, I neglected a significant component in the earlier calculation (the salt water buoyancy addition of about 2.4% of your dry mass). With that included, your drysuit buoyancy -- and thus total ballast required -- is about 21.5 lb to be neutral at the safety stop with empty wing (from -26.5 lb/12 kg lead, -1 lb reserve air, -0.5 lb empty 12 l cylinder, -2 lb regulator, +2 lb guess at an empty BC, and +6.5 saltwater adjustment). At the beginning of the dive, you will have 6 more lbs of air than at the end, so the lift from the wing has to be at least 21.5+6 = 27.5 lb.

Consequently, a 30 lb wing would be fine with integrated weights in your Scotland scenario. Again, during a normal dive you'd have loads of lift to assist people as a buddy or DM (between 24 lbs and 30 lbs) or on the surface waiting on a boat. Hopefully it's clear that if your DS totally flooded, your wing would get you up no problem (because you conveniently chose one that would float without the benefit of your suit buoyancy).

The only caveat is you seemed to be guessing about the weight in your current setup ("closer to 12 or 13 kg"), and I was guessing about the buoyancy of your current BC (at +2 lb). It is likely that BC is even more buoyant, which would basically cancel out a lead increase to 13 kg.

 

[-JD-]

TecLine (Poland) also has single-tank wings up to the 21-22L range which should put you near the 40lb range ...

SINGLE TANK CONFIGURATION - Teclinediving

Tecline single tank configuration - your guide to build a personalized equipment configuration for your recreational dives.

teclinediving.eu

Remember if your rig can't float you in your rig, weighted, in a flooded dry suit, you need to be able to ditch significant weight extremely reliably and pretty quickly. Covered by above:

 

[Giovanni Giuriani]

I must apologize, I neglected a significant component in the earlier calculation (the salt water buoyancy addition of about 2.4% of your dry mass). With that included, your drysuit buoyancy -- and thus total ballast required -- is about 21.5 lb to be neutral at the safety stop with empty wing (from -26.5 lb/12 kg lead, -1 lb reserve air, -0.5 lb empty 12 l cylinder, -2 lb regulator, +2 lb guess at an empty BC, and +6.5 saltwater adjustment). At the beginning of the dive, you will have 6 more lbs of air than at the end, so the lift from the wing has to be at least 21.5+6 = 27.5 lb.

Consequently, a 30 lb wing would be fine with integrated weights in your Scotland scenario. Again, during a normal dive you'd have loads of lift to assist people as a buddy or DM (between 24 lbs and 30 lbs) or on the surface waiting on a boat. Hopefully it's clear that if your DS totally flooded, your wing would get you up no problem (because you chose one that would float without the benefit of your suit buoyancy).

The only caveat is you seemed to be guessing about the weight in your current setup ("closer to 12 or 13 kg"), and I was guessing about the buoyancy of your current BC (at +2 lb). It is likely that BC is even more buoyant, which would basically cancel out a lead increase to 13 kg.

Thanks a lot, I’ve got a new dry suit and undersuit which I haven’t used yet so am not 100% sure how much weight I’ll need. I’m going diving this weekend so should find out, that’s why I’m still guessing on the weight. So hopefully after that I can figure out exactly if the wing would be enough.

I’m guessing the salt water adjustment though only counts when I’m wearing the rig no?

 

[Giovanni Giuriani]

Also on a separate note the Hollis St system has a couple of D rings on each shoulder and one on each hip, I know this is not standard for backplate and wing harnesses but I don’t get why would this be a problem? Or at least not advised?