In determining lift, do I factor my buddy?

[Pullmyfinger]

Hi,

I'm soon going to be buying a backplate/wing. I've searched and read through every thread I could get my hands on. I have read the different views on how to determine required lift by considering my exposure protection.
I've also read over the debates concerning doing a buoyancy check with you head above the surface vs. being neutral at 15 ft.
I understand the need for having you wing float my rig if I'm not in it. If I have to either ditch it or don it in the water.
I have a pretty good understanding of all of these things based on reading these topics as posted around the board.
I will factor all of these variables and make my choice on wing size.

One question remains for me.

Others have mentioned that you should allows for the possibility of a failure in your dive buddies wing or dry suit, if we happen to be diving dry. What is the standard practice in allowing for this?
I f I have to factor for the unlikely event of wing failure or dry suit failure should I not also give consideration for a failure of my dive buddies gear?

Thanks for pondering my question?

Take care,
Mitch

 

[Tomikp]

My opinion is, you should choose a BCD appropriate to your other gear. It is a nonsense to use much bigger wing only for situation when your buddy needs your help to get to the surface. But Everytime your BCD should have some reserve.

 

[TSandM]

If my buddy is diving dry, he's already got redundant buoyancy. The only way he is going to be unable to put gas in one space or the other is if he is out of gas altogether. In that case, one of you can orally inflate his wing, if you absolutely require lift to get him up from the bottom. If he is properly weighted, and his tank is empty, he should be neutral or buoyant, so I can't see this being an issue in that case. If his tank is big, and full, and his gas supply has been interrupted by equipment failure, he's going to be at most 10 lb negative (HP 130) and he should be able to swim that to the surface, where one of you can orally inflate the wing.

 

[masterof0]

Also keep in mind in an emergency situation, if he/she happens to be negatively buoyant, either you or they can always ditch weights to overcome that. As you start to rise, any air that is in the BC or drysuit will expand increasing he amount of buoyancy.

As stated before, your wing should be able to accommodate your rig and any gear you dive with.

 

[cool_hardware52]

Hi,
One question remains for me.

Others have mentioned that you should allows for the possibility of a failure in your dive buddies wing or dry suit, if we happen to be diving dry. What is the standard practice in allowing for this?
I f I have to factor for the unlikely event of wing failure or dry suit failure should I not also give consideration for a failure of my dive buddies gear?

Mitch

What failure of your teammates equipment would require him to rely on "your" buoyancy?


Tobin

 

[Pullmyfinger]

Thank you,

I wanted to hear any views on this since I've read other postings that raised the subject when discussing wing size.

Take care,
Mitch

 

[Pullmyfinger]

What failure of your teammates equipment would require him to rely on "your" buoyancy?


Tobin

There are none that I can really think of, it seem very unlikely. I knew that I have read some opinions brought up in the past stating that they factored this in.
I wanted to get some opposing viewpoints on the subject.

Take care,
Mitch

 

[nereas]

There are dozens of ways to determine how much lift your wing should have. Everyone swears by a different way.

I myself like the rig to be able to float itself in the water, so that if I am getting out of or back into a RIB (rigid-hull inflatable boat), I like to inflate the wing and put the rig into the water first. Then it sure is nice if it floats.

The only way that it can float, is if the wing has enough lift to buoy-up your tanks, bands, manifold, regs (2 or 3, depending on if you use argon), lights (2 or 3, depending on whom you talk to), knife(s), and the weight of the air/nitrox/trimix within the tanks (0.08 lbs per cu ft), and the plate itself, plus any weight plates attached to the plate (if any).

So that is what you need to add up. The total will vary, depending on the tank composition (alum or SS), tank size, and plate weight.

For me, this comes out to a 40 lb oval wing for single-tank cold-water diving, or a 50 lb U-shaped tech wing for double-SS-tanks.

Your answer may vary. That is why it is best if you do your own math.

Instructors and D/Ms who must work with over-weighted or under-weighted dive students might be able to make an argument for a larger wing, plus they often must lug around heavy float augers, which can add about 5 more lbs than this. But if you are asking this question, then you are not an instructor nor a D/M, because many instructors tell their D/Ms to get a back-inflation B/C with extra lift to be able to deal with the students' extra weights (putting them on and taking them off) as well as the augers.

Great question, though.

 

[nereas]

If my buddy is diving dry, he's already got redundant buoyancy. The only way he is going to be unable to put gas in one space or the other is if he is out of gas altogether. In that case, one of you can orally inflate his wing, if you absolutely require lift to get him up from the bottom. If he is properly weighted, and his tank is empty, he should be neutral or buoyant, so I can't see this being an issue in that case. If his tank is big, and full, and his gas supply has been interrupted by equipment failure, he's going to be at most 10 lb negative (HP 130) and he should be able to swim that to the surface, where one of you can orally inflate the wing.

And if your buddy is an uncertified dive student, then all bets are off!

 

[bigken462]

What failure of your teammates equipment would require him to rely on "your" buoyancy?


Tobin

Diving wet with a set of doubles on and the whole inflator hose coming off the BC to name one.

Ken