backplate and wing for GUE courses

[sea_ledford]

OK this is a lot to unpack and raises some questions. One of the biggest is what is the downside to a 40lb wing if I only "need" a 30lb? I mean, I get that a bigger wing is technically more drag but it seems like that would be minimal. I was reading something about how one manufacturer (was it Deep6?) dropped the 20lb wing from their lineup because the 30lb was only very slightly wider. Now of course that means that it gets the lift from somewhere- maybe extra thickness or whatnot. But all things considered, is a 40lb wing with 30lbs worth of gas in it that much of a drag in the water?

I tend not to believe what I hear from scuba retailers because they depend on selling gear. I am just not sure what this guy had to gain by telling me that I should go with a 40lb wing. I mean he had all sizes and could have just as easily told me 30lbs. On another note, if a 40lb wing isn't right for a big guy in a really thick wetsuit diving cold water, who would it be for? It's a singles wing- it's not made for a twinset or sidemount. Oh and for the sake of argument let's assume (because this is the case) that the person who told me this has decades of experience teaching cold water diving and DIR style.

In the end this is just a math problem, right? I mean- either the math supports a 40lb wing or it doesn't.

The point on suit compression is an excellent one, and my brain always goes back to the FlowState Divers video on buoyancy that says the only point of the air in your wing is to offset the weight of the gas as it changes during the dive. But that's clearly leaving out an important component!!

My bigger concern with larger wings is not so much drag as air trapping. It just makes it a lot harder to get all the air out of the wing. That is mostly dependent on the shape of the wing, and the placement of the dumps, but in general, the bigger the wing, the harder it is.

I have often wondered what the point of a 40 lb wing is. A super muscley 6% body fat guy in a 10mm wetsuit, and HP120 tank? Or a working diver that just has a lot of heavy stuff attached them? No idea.

See if you can try out the wings in a 3mm suit in a pool, that will probably be similar. If it's close, go up to the 40.

 

[JoeTPhilly]

My advice would be to speak with your GUE instructor before buying anything. You will get the e-learning and will learn about the balanced rig. Also, heavy wetsuits aren't really a GUE thing...

 

[inquis]

[HP100s are] Super negative at the start of the dive and still somewhat negative at the end.

There is no free lunch. An AL80 is about 4.5 lbs positively buoyant when empty. You HAVE to offset that with something (lead or other gear) in order to use it, perhaps to the equivalent of -0.5 lb. Conveniently, an HP100 is already about -0.5 lb empty. The ONLY difference (buoyancy-wise) is that you would have lead to possibly ditch lead in the AL case, if you ignore all other gear. But you DO have other gear, and with that wetsuit, you will have plenty of lead available to drop if needed, even with an HP100 tank. Hopefully you can see it's the TOTAL buoyancy that's important. The individual gear buoyancies can be traded off against each other.

I'm not saying you should use this or that tank. It's just that I think your wariness of a steel tank stems from a misunderstanding -- one that is quite common, actually.

 

[lexvil]

Maybe just get what you want and ignore dogma.

 

[tursiops]

Maybe just get what you want and ignore dogma.

He's going the GUE route; he wants dogma.

 

[lexvil]

He's going the GUE route; he wants dogma.

If he is still pre lobotomy he has a chance.

 

[rongoodman]

There's a Halcyon SS plate and harness posted in the classifieds right now.

 

[Sol]

No drysuit for now- my spouse is saying that I spend "too much money on diving" but I don't really think that is even a thing, is it?

 

[inquis]

the FlowState Divers video on buoyancy that says the only point of the air in your wing is to offset the weight of the gas as it changes during the dive. But that's clearly leaving out an important component!!

Yes, it should also compensate for suit buoyancy lost from about 15 ft to the bottom. Even at 130 ft, that will be less than half the surface buoyancy (because that value neglects the solid parts of neoprene).

All this to say, I don't know how negative I will be if my wing failed

Figure 9 lbs for compression loss and 5-7 lbs of non-reserve gas, and you are at less than 15 lbs negative while diving if properly weighted.

It is true the rig has to be able to float itself (without the help of you & the wetsuit) should you take it off to, say, get into a small boat. If you use only integrated weight, that could be up to the surface buoyancy of you+suit. That'd be about 21 lbs for me in an XXL 7mm suit (6'2", 220 lb) in salt water, so a fair bit of room to 30 lb.

 

[HamTrainChickenLaser]

My bigger concern with larger wings is not so much drag as air trapping. It just makes it a lot harder to get all the air out of the wing. That is mostly dependent on the shape of the wing, and the placement of the dumps, but in general, the bigger the wing, the harder it is.

I have often wondered what the point of a 40 lb wing is. A super muscley 6% body fat guy in a 10mm wetsuit, and HP120 tank? Or a working diver that just has a lot of heavy stuff attached them? No idea.

See if you can try out the wings in a 3mm suit in a pool, that will probably be similar. If it's close, go up to the 40.

Gotcha on trapped air- that makes sense!!

OK wait- in a rashguard and shorts I take 14 lbs of lead. With a 3mm wetsuit I use 18 lbs. Surely my 8mm wetsuit (well, semi-dry which is wet of course) will be much harder to sink, no?