Wing Lift Vs Depth vs Amount of Bottles

[Remy B.]

Is there a relationship or rule according the wing lift capacity and the depth and the amount of bottles ??

as a diver gets more experience his dive gear evolve as well, but divers put limits of to which depth they eventually want to reach and stay above that.

I know the amount of bottles you need to carry depends of the amount of time you will spend down there, but their are practical limits to it and it is not often to be wandering for long periods of time just for the sake of racking extensive hours of Deco.

for example, a diver sets a limit of 100m but usually dives between 45m and 65m, lets say he calculates his gas for no more than 4 bottles don't matter the depth he just base his amount of time he will spend down there based that he only will carry 4 bottles with him, (100% O2 Deco bottles will be either with him or at a line depending the depth and time he will be down there ) but the point is 4 bottles with him at all time two AL 100 and two AL80 fro example ( lets stick to AL bottles for this example I know there are better options with steel bottles )

correct me if I'm wrong but I didn't understand right maybe, that as deeper you go the lift capacity of your wing need to be higher as the pressure of water affects the capacity of inflation, since as deeper you go you require more gas bottles this makes it worse.

assume that the diver is normal size person 187lb with a 7mm wetsuit

Example 1: dives at 45m for X amount of time and a 35lb lift Wing do the work

Example 2: dives at 65m for X amount of time and his 35lb lift wing still do the work

Example 3: eventually dives at 75m for X amount of time then he needs a 45lb lift wing for this

Example 4: he rarely reach 100m for X amount of time then he needs a 60lb lift wing for that dive

based that he carries 4 bottles with him at all times is there a rule of wing capacity Vs depth ?? or will be a 45lb wing still do the job at 100m ?? and the 35Lb still good for 75m ??

or did I understood completely wrong the selection of wings regarding pressure of water + weight at depth

Thanks for your clarification on this.

 

[PfcAJ]

In real life, if you're carrying a bunch of stages they're going to have helium in them. That makes them neutral (or close to it) or positive. At that point, wing lift doesn't matter.

I do not adjust my wing for # of tanks carried because of this. 8'' backgas tanks get a 55 or 60lb wing, 7'' backgas tanks get the 40lb wing.

There are folks that strap on a bunch of low helium/steel stages, and end up with ridiculous wings. I think that's silly.

For example, I did a dive (a few, really) requiring lp104s with 15/55, 3 bottom stages (15/55), a 120 bottle (35/25), 70 bottle (50%), and a steel 72 for oxygen, and 2 scooter. Thats SIX bottles, and no setup divers or any luxuries. Didn't change anything from my normal equipment setup and certainly nothing regarding a bigger wing. The only bottles that we're a little heavy was the 72 and the 50%. The rest were neutral or close to it.

 

[advlyfe]

I would like a picture of all that gear attached to you. That sounds nuts.

Sent from my SAMSUNG-SGH-I337 using Tapatalk

 

[PfcAJ]

I would like a picture of all that gear attached to you. That sounds nuts.

Sent from my SAMSUNG-SGH-I337 using Tapatalk

It is.

2 on chest (oxygen and the 120, which we went in breathing), the rest divided into 2 leashes on the left hip. I probably moved the 50% to my chest after I dropped the o2, that's a thing I typically do. Light bottles on the hip are pretty reasonable.

 

[advlyfe]

For these dives, what was your goal? All this planning doesn't amount to "lets look at the pretty fish" or does it? Interested in learning more.

Sent from my SAMSUNG-SGH-I337 using Tapatalk

 

[PfcAJ]

For these dives, what was your goal? All this planning doesn't amount to "lets look at the pretty fish" or does it? Interested in learning more.

Sent from my SAMSUNG-SGH-I337 using Tapatalk

The particular one I'm referencing was to get familiar with a section of cave rarely visited to ultimately look for exploration leads. I think we turned the show around roughly 3.5k in at an avg depth of 220. A scooter issue on the way in stalled us for a good while at the 120 drop and prevented a longer dive

Other ones we've done that involved similar logistics were actual exploration dives. Generally speaking I feel that a triple stage dive at those depths are at the outer fringe of OC diving. RBs are just better tools for that kinda stuff.

 

[tbone1004]

agreed with AJ on the balance point between ridiculous OC and pretty "normal CCR" type dives.

That said, depth shouldn't matter because you should be in a drysuit for those dives, so depth compensation is irrelevant. For number of bottles, it depends on what they are. 2-3 stages of 32%? yeah I'll put on a larger wing than my normal 45lb that I use with small doubles. In sidemount you're kind of SoL as far as wing sizes, but there's a few rigs out there that can help. At deep depths, AJ indicated the bottles full of helium weighing less, so that's just less lift required.

I have two wings for twinsets/doubles. 42lbs and 57lbs. Mainly for when I'm diving LP72's/100's/120's *the 7.25" tanks he indicated, though I'll also use them if borrowing LP95's*, and the 57 for when I'm using those with multiple stages, or with LP104's.

 

[Doppler]

Is there a relationship or rule according the wing lift capacity and the depth and the amount of bottles ??

The baseline calculations remain unchanged.

One either buys a fish or luggage scale to determine the in-water weight of each "bottle" or refers to the manufacturer's specs for working values. Gas weight is added (manufacturers often give in-water weight for cylinders charged to working pressure)... when these figures are not applicable (under-filled or over-filled cylinders for example) long-hand cals are done... air and nitrox is around 1.2 - 1.3 grams per litre / one pound per 13 cubic feet (trimix is much less). This starting weight helps to identify how much lift is needed at the beginning of the dive... the buoyancy shift helps to determine how much ballast is needed at the end of the dive.

Great depth is not a primary factor in one's choice of wing... however, the speed at which one's LP inflation system can move gas from a cylinder to one's buoyancy cell to arrest descent is.

Hope this, coupled with the excellent responses given already, will help answer your question.

 

[Nasser]

Another thing to consider is how the ballast is distributed. Your wing should also be able to float your rig on the surface so if you're using v-weights or integrated pockets on your harness rather than a separate weight belt, you should take that into account.

 

[cool_hardware52]

correct me if I'm wrong but I didn't understand right maybe, that as deeper you go the lift capacity of your wing need to be higher as the pressure of water affects the capacity of inflation, since as deeper you go you require more gas bottles this makes it worse

You are wrong. At depths that divers operate at the increased density of the inflation gas is trivial, the density of the water is unchanged wrt to depth until you get sea trench deep.

Many of your other assumptions are wrong too, but this is particularly glaring.

You need to understand gas planning before you can start to understand required lift vs extra bottles.

In general if a tech dive goes according to plan the diver will exist the water with ~50% of the gas (total, everything, deco, back, bottom stages) they started with.

If things go side ways and there is a need to empty bottles these can easily be abandoned if they become problematic.

Just as Pj also noted I don't change my wing capacity based on how many bottles I take.


Tobin