Optimum BC for various setups

[mcpowell]

Okay, I know this is a bit ambiguous, but I was going to ask the gear-heads at the Try Tech Demo Day this weekend, but now it’s been postponed. So now I’m asking the good folks here.

I have been reading about backpacks and wings, but I need some clarification please:
1) If you’re going to dive a single tank, you use a backpack/wing set up for a single tank...right?
2) If you’re going to dive with twin tanks, do you need a different backpack and wing?
3) If you’re going to sling 2 tanks, but have nothing on your back, what do you use as a BC?

Do most people have one setup for each of the above? Or is there a modular system?

Gah...I have no idea the stuff I don’t know!

Is there a “Tech Diving for Dummies” article/book/forum etc?

 

[Marie13]

I don’t do number 2, but I do 1 and 3.

Halcyon BP/W (SS BP and 40 lb wing) for single tank BM.

Hollis SMS75 for sidemount.

I use the same tanks for both (HP80s).

 

[rongoodman]

A BP/W set-up will(probably) use the same plate and harness for either singles or doubles but the wings will differ, both in the amount of lift required and the physical dimensions. Two tanks on your side is side mounting. There are numerous harness/flotation systems out there for that, roughly broken down into those optimized for the light aluminum cylinders common in Mexican caves, versus the heavy steel tanks used in Florida.

 

[runsongas]

diving a single aluminum tank in sidemount aka monkey diving is an option also

 

[Centrals]

Only one set up.
1. BP/W
2. Same set up but with bigger wing
3. Why would I want to dive 2 tanks but with room for rent on my back? Single tank on my back and the other clip in front.

 

[Bowers]

a steel backPLATE will work for singles or doubles (unverified but ive been told you can crack an aluminum by using it for doubles).
the wing will be wider for doubles but some of the mid range bungeed wings can be used for single or double like the hog 32lbs with bungee.
there are adapters that can be used to make a backplate and wing suitable for sidemount diving but it seems better to get a dedicated rig for that.
as far as modular and useful in multiple setups... backplate and wing is superior to other BC's

 

[elgoog]

a steel backPLATE will work for singles or doubles (unverified but ive been told you can crack an aluminum by using it for doubles).

Aluminum plates most certainly do not crack with doubles. Let this story go from "unverified" to "verified to not be true".
Almost everyone I know who dives steel doubles uses an aluminum, kydex or carbon fiber plate because you want less weight high on your torso to be able to trim out properly. A steel backplate is actually counter productive here.

 

[tbone1004]

@Bowers aluminum backplates will have the bolt holes rounded out over long periods of time, but we're talking many hundreds of dives since the steel bolts are harder than the aluminum backplate.

@mcpowell
1- I use a freedom plate with VDH 30lb wing for singles diving due to preference for double hoses at this time.
2-I use a DSS stainless or kydex backplate with a 50lb doubles wing. I can use either of the DSS plates with single tanks, but the wing does have to change to a singles wing.
3-I use a Hollis Katana prototype for sidemount

Now, depending on the type of diving you are doing predominantly there are some rigs that can be made to work. If you primarily dive backmount singles, but need to sidemount infrequently for some reason, you can look at the Toddy style system which takes two backplates and sandwiches a wing between them. It is rather annoying to thread back and forth, but it's possible.
If you primarily dive steel tank sidemount, but on rare occasion you need to use backmount singles or doubles, something like the Dive Rite Nomad XT will work. I did this for many years.

Realistically if you are regularly diving backmount and sidemount, you need dedicated rigs and prioritize based on priority.

 

[g1138]

1) If you’re going to dive a single tank, you use a backpack/wing set up for a single tank...right?
Backplate & "singles" wing; usually rated between 18-40lbs of lift

2) If you’re going to dive with twin tanks, do you need a different backpack and wing?
Same backplate but with "doubles" wing; usually rated between 30-60lbs & is much wider than a "singles" wing

3) If you’re going to sling 2 tanks, but have nothing on your back, what do you use as a BC?
Sidemount BC or Bp/W with modifications to use sidemount configuration.
Most divers are now going towards dedicated sidemount BC's since they're more effective and now mass produced by many different manufacturers.
For sidemount BC's you'll see the keyword sidemount in the description or the name. They are not cross-compatible with single or doubles backmounting.

Do most people have one setup for each of the above? Or is there a modular system?
If they dive all systems then yes. Most folks I hear who transition to sidemount never do backmounted doubles ever again. It's a different style and divers have different preferences or environments. Diving in narrow restrictions, you'll predominantly use sidemount as doubles create a very tall profile that's not conducive to squeezing through those cave/wreck restrictions. Sidemount allows you easily detach tanks and shove them ahead and in front of you before you crawl through as well.


Is there a modular system for all? Technically yes, practically no.

Sidemount started originally using backplates, but now gear has been created that's more niche for it, so no longer is that the common practice case.

Bp/W's are modular. You can use the same plate and mount the appropriate wing and tanks.
Single tanks are used with cambands (ie. tank straps) and a single tank adapter (STA) or more recently just straight against the wing, since most manufacturers are now putting mini tank rollers/braces on the wing itself. Those tank rollers make the STA redundant & gives the tank a lower profile against the diver's body.

Double are used with bands and go straight on, sandwiching the wing to the plate with carriage bolts.

Sidemount BC's are also modular but aren't cross-compatible with traditional Bp/W's.
This allows you to customize the appropriate sidemount-wing lift for your needs with the sidemount harness.

 

[J-Vo]

Side Mount rig for anything from a single AL40 to double LP108s with 4 AL80 Stage/Deco bottles. One harness for the dry suite and one for the wet suit. The wing gets moved between the two harnesses.