How much lift is too much lift?

[akivisuals]

So I've been looking into a SS backplate/wing setup since my Aqualung BC took a dump and have been getting such a varied response to the amount of lift I need. Some very highly regarded people have said I could use a 20 lb wing while others recommend a 35-40 lb wing. I'm a bit confused as to the direction I should take. I know that I want enough lift for all the stuff that I might wind up taking along whether that's a camera setup or a game bag filled with lobster or a speargun and fish.

Some background. I'm 145 lbs. and 5'4". I dive mostly SoCal water (high 50's-low 70's) in a wetsuit (at the moment). 7mm full suit with a 5/3 hooded vest, 3mm gloves, and 5mm boots. I've tried to sink it all wrapped together and am looking at around 16 lbs. or so to get it to sink. Maybe less, everything is so squirrelly trying to get it all stable underwater. My tank is a steel HP80. I carry a 13cf pony bottle with it's own regulator at times. In my Aqualung Dimension i3, I use 12 lbs. of lead when I use the pony and around 14 lbs. when I don't. I'm not sure if this is "perfect" weighting but it seems to work for me.

Can anyone suggest how much lift I require? I'm thinking that a 35-40 lb. lift wing will be good if I'm hunting or carrying heavier camera gear. Thoughts? Recommendations? Thanks y'all, the recommendations I've gotten here have been really helpful so far!

 

[ams511]

You will use less weight with a BP/W because the plate is metal and the rig has less padding. How heavy is the camera equipment underwater? You can always take weight off the belt to compensate for the weight of the camera equipment. Where do you want to carry the weight? If you use weight pockets a 20 lb is too small. The BC will not float on the surface without you in it.

 

[Dive Right In Scuba 2]

My personal thought is a 28-32lb wing would fit the bill for you.

 

[Bob DBF]

I determined mine by asking the manufacturer of my jacket what the buoyancy was and bought the same amount, a 40# OxyCheq wing. I don't believe the wing actually gives 40# as it barely keeps my rig afloat when full and I calculate that can be up to 30#. Part of that is because the oval wing can not inflate completely because of how the wing fits around the tank, as far as I can determine. Other than that I've found it to work very well indeed. I dive wet in cold water with some big steel tanks and sometimes trim weights. I'm 6' 215# and use a 7mm farmer john in NorCal.


Bob
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All my life I've wanted an excuse to wear a knife, and here I have found a sport where it is actually encouraged~ Dave Barry

 

[Jim Lapenta]

I agree with Aaron. 30-35 lbs will be fine. I would not go any less than that. Especially for steel tanks. I sell a 23 lb wing but only recommend it for the person using al tanks with little or no weight. Even then I don't like to recommend it to some of those divers. One thing I always tell anyone considering a wing is to also take into account how much of a safety margin you want. What do you feel better with if you should have to support another diver on the surface for a few minutes or longer. 23 lbs or 32 lbs of lift? I know what my choice is. Not to mention for scuba the difference between a 23 and 32 size wise is negligible. Some worry about "increased drag". Really? On scuba that is supposed to be slow, relaxed, and easy swimming? I don't want a doubles wing that'll taco a tank and be hard to vent. But a 32 doesn't present any issues. The benefits of the additional lift far outweigh any "increase" in drag.

 

[buddhasummer]

I use an 18 with Alu plate, Alu tank, 5mm suit and about 3kgs of lead when tropics diving. I use a 30 with steel plate (2.8kg), steel tank, two piece 7mm, can light, no lead wetsuit diving. A 40 drysuit diving, heavy plate (5.1kg), weighted STA (2.7kg) steel tank, 3kg on cam bands can light and 4kg on belt. This is just an example of course. Agree with others something around the 30 mark would probably be ok. If you can approximate your total weight, plate, tank, camera equipment, lead carried etc it'll give you aa good idea. There is a big difference between a 20 and a 40. Agree a 20 likely be too small.

 

[dumpsterDiver]

Fish will make you float, lobsters will make you sink. Are you happy with the current BC. what is the lift of that BC? I would want around 35 lbs or so capacity.

 

[LeadTurn_SD]

Hi akivisuals,

Good answers already, so rather than chime in with another number....well ok, heck, a 32-35 lb wing should be fine :blinking:, not too big, but with enough lift to provide a "margin" of safety for most single tanks and the amount of lead you carry... I'll instead suggest calculating your own minimum lift requirements based on your current exposure suit and weighting.

With no redundant "lift" from a drysuit, you do need to consider how "heavy" (negatively buoyant) you can be in three states, with a full tank:

1.) At the surface, with all gear on. Your wetsuit is providing some lift to help hold you and your rig up.

2.) At max depth when your wetsuit is fully compressed and providing very little lift.

3.) At the surface, but out of your rig (for example, you take off your rig to climb into a small boat). The wing needs to float your rig without the added lift your wetsuit provides on the surface.

To arrive at these numbers, you need a fairly good estimate of the buoyancy of each piece of gear you are wearing, and know how that buoyancy changes at depth. I don't know what tank you use, so using the ubiquitous Al 80 and a bare bones BP/W rig without a pony or camera equipment, using your current wetsuit, this is what I would look at to begin getting a rough idea of the bare minimum lift required.... I'll do it for "at depth":

• Your wetsuit will of course lose buoyancy as you descend, and if your measurement of 16 lbs buoyancy for your wetsuit is in the ballpark, for safety and ease of calculation you should consider that you will need to at least compensate for that 16 lbs of lost lift at depth to just stay "neutral", but the reality is that you'll be more "negative" than that at depth, and need to consider all the gear you are wearing.

So how negative could you really be at depth? Again, for simplicity consider the wetsuit to be fully "crushed", providing no lift, and use the buoyancy, not dry land "weight" of the rest of your gear:

• A full aluminum 80 is around 2 lbs negative (with valve). (Steel tanks will be more negative)
• Your regulator set will typically be around 2 or 3 lbs negative.
• Your backplate, wing and Hogarthian harness is probably 5 lbs negative, give or take (with a totally empty wing).
• Your weight belt is currently 14lbs

So adding up the negative buoyancy and ignoring any potential residual positive buoyancy, with this "bare bones" equipment setup, at max depth, I'd use 2+3+5+14= 24 lbs lift as the very bare minimum, "no frills" lift at depth.

You'd be right around "neutral" with that hypothetical 24 lb wing fully filled, you may still need to gently kick initially to ascend. Be aware that the "rated" lift on a wing could be different (less?) than the actual lift if it cannot fill fully (if the tank impinges on it).

With the AL80 "bare bones" rig you should be able to swim your rig up ok, even without a functioning wing, assuming good fins and a fairly strong kick . Depending on what equipment you add to the bare bones kit, or using a steel tank, you'll need to adjust the bare minimum lift requirement upwards.

If you are weighted properly (which will usually mean you are negative by the amount of the weight of the air in your tank at the start of the dive), you should also have enough lift on the surface when wearing your BP/W since your wetsuit is contributing lift.

Now should you decide to shift weight off of your weight belt and onto your rig, you would need to consider that it might not have enough lift to float itself on the surface. This will be a function of how much weight you shift to the rig, the type and size of the tank, etc., but you could end up with a rig that could not float itself on the surface with a smallish wing.... that would be something to watch out for.

So, the above considerations are the why's behind the fine folks in this thread recommending wings a bit bigger than the 20 lb wing someone had apparently recommended to you... and leads back to the recommendation of around 32 lbs or so as probably being an ok choice.

If you dove in a thin wetsuit in warm water, a smaller wing would probably be just fine, but if you load yourself down with more "stuff", than a slightly larger wing might be needed.

Best wishes.

 

[akivisuals]

I dive single Steel HP80s normally. The lift on my current BC seems fine. It's 35 lbs. So I was thinking a Halcyon 40 lbs wing, DSS LCD30, Dive Rite Traveler at 25 lbs, or the Voyager at 35 lbs. Thoughts?

 

[dumpsterDiver]

25 is too small and I think Lead turner forgot your pony bottle and extra regualtor in his detailed list