82 replies to this topic

[Dive_Girl]

Yep, flood your drysuit and see how much lift you need to get off the bottom. Then start doing your calculations from there.

Did that this past March in my doubles in 42 degree water - I think I'll pass on doing it again.

I will run a surface test based on:

"Buoyancy Compensator: Adjusted based upon needed lift whether one is diving single or double tanks. Buoyancy should be sufficient to float equipment by itself while at the surface." Click for source

[PerroneFord]

Well, what did you learn from it? How negative is your suit when flooded?

Ideally, your tanks, lights, and other gear should be in balance with lift of your drysuit. Then you are only carrying weight to offset the buoyancy swing of the tanks. You essentially dive with the wing empty or nearly empty all the time.

If the suit floods, you just need enough lift to overcome it.

[Dive_Girl]

Well, what did you learn from it? How negative is your suit when flooded?

Ideally, your tanks, lights, and other gear should be in balance with lift of your drysuit. Then you are only carrying weight to offset the buoyancy swing of the tanks. You essentially dive with the wing empty or nearly empty all the time.

If the suit floods, you just need enough lift to overcome it.

I don't use my suit for primary lift. My suit carries minimal air in it to take off squeeze and add warmth. Drysuits don't have "quick dumps" and undergarments can possibly inadvertantly trap air, so the less air you have in them throughout the dive, the better - at least this is my opinion. Using a drysuit for primary lift opens up tons of failure points to me.

[PerroneFord]

Well, what did you learn from it? How negative is your suit when flooded?

Ideally, your tanks, lights, and other gear should be in balance with lift of your drysuit. Then you are only carrying weight to offset the buoyancy swing of the tanks. You essentially dive with the wing empty or nearly empty all the time.

If the suit floods, you just need enough lift to overcome it.

I don't use my suit for primary lift. My suit carries minimal air in it to take off squeeze and add warmth. Drysuits don't have "quick dumps" and undergarments can possibly inadvertantly trap air, so the less air you have in them throughout the dive, the better - at least this is my opinion. Using a drysuit for primary lift opens up tons of failure points to me.

I don't understand how that relates to my question. Perhaps you are being thrown off when I say "drysuit lift". Howabout I say undergarment loft. When you take the squeeze off, how positive are you in the water?

Edited by PerroneFord, 26 July 2006 - 09:10 PM.

[ScubaDadMiami]

A wing needs to get the diver to the surface, hover a diver at depth in less than ideal conditions including downdrafts, and a wing needs enough lift to get a victim to the surface with the diver/operator in an emergency. A wing needs to do this in the event of things like flooded suits, flooded loops, hauling victims with full tanks, and it needs to be there with enough leeway for emergencies.

On a properly weighted diver, a wing will not need to be inflated to its capacity or anywhere close (other than for convenience at the surface) except for in the case of an emergency. So, having some leeway allows the user to keep the wing fairly streamlined even if it has a larger capacity, and it allows for some extra lift in the case of an emergency.

This does not mean that one should use a doubles wing for a single tank because the wing could wrap around the single, not allowing gas to vent, causing problems. However, this is not a contest to see who can survive a dive with the least lift possible anymore than it is a contest to see who can carry the least amount of lead. You need what you need, and that is what you should use. Like many other things in life (and diving), everything has a plus and a minus, and becomes a balancing act.

[Dive_Girl]

This does not mean that one should use a doubles wing for a single tank because the wing could wrap around the single, not allowing gas to vent, causing problems.

I don't use a doubles wing for my singles. My singles wing could double as a back-up for my doubles. It is a DiveRite that has a minimal cord that tucks the wing which doesn't trap air (and can be removed when used for technical diving) - I dove it in NC - if it had stood out as excessive - I think you would have noticed it.

[Dive_Girl]

A wing needs to get the diver to the surface, hover a diver at depth in less than ideal conditions including downdrafts, and a wing needs enough lift to get a victim to the surface with the diver/operator in an emergency. A wing needs to do this in the event of things like flooded suits, flooded loops, hauling victims with full tanks, and it needs to be there with enough leeway for emergencies.

On a properly weighted diver, a wing will not need to be inflated to its capacity or anywhere close (other than for convenience at the surface) except for in the case of an emergency. So, having some leeway allows the user to keep the wing fairly streamlined even if it has a larger capacity, and it allows for some extra lift in the case of an emergency.

Excellent.

I also find when I buy something, I don't want it to be something I'll grow out of. So I want a wing that I won't grow out of - those 300' dives with crazy tanks and scooters aren't too far from my future...

Off to dinner - have a good night y'all!

[PerroneFord]

However, this is not a contest to see who can survive a dive with the least lift possible anymore than it is a contest to see who can carry the least amount of lead. You need what you need, and that is what you should use. Like many other things in life (and diving), everything has a plus and a minus, and becomes a balancing act.

Agreed, however, I think a lot of divers are overweighted unnecessarily, and have wings that are far too large unnecessarily. My 27# singles wing is nearly empty on my dives and I am in a wetsuit. In a Drysuit, I'd have to add a few pounds just to sink. Without any flooding issues to worry about, I am about 8# negative in the water max when I am in my AL80 doubles. The 45# doubles wing is PLENTY.

[Diverbrian]

All that I know is that my steel BP and double E8-130's drop me like a stone when I deflate my BC. Add my LP45 that carry O2 in along with another stage bottle and while my wing doesn't get really pushed (I dive a 55 pound wing.), but I can guarantee that it will have some air in it. As things empty out in my tanks, I have wound up actually kicking down at my deco stops at times due to air trapped in my drysuit undergarments and my tanks not being enough negative with less air in them to compensate. I generally need two or three tries to get all of the gas out of my drysuit undergarments on ascent. That gas typically has to work itself out a bit and doesn't like to come out on the first try.

I dive a wing with 35 pounds of lift for singles.

I will say that too large of wing has been known to trap air and be difficult to vent. I have seen that happen to my buddies at times. Too small leads to obvious issues in unplanned for situations (such as the drysuit flood).

[Geek]

As one who actually dives here in the NE, I would like to add a few thoughts:

First, I don't believe the numbers that manufacturers claim. They're useful only in telling you that a higher number lifts more than a lower number, not in telling you the actual number of pounds of lift.

Having said that, NE diving is mostly wrecks on a hard bottom. I don't think you need to worry about walls locally, so what you really need is enough lift to get you and your stuff off the bottom with your drysuit flooded, early in the dive while the tanks are still full, and therefore negative. Your stuff is going to include a backup of just about everything because the visibility stinks and if you drop it, you'll probably never see it again.

Your stuff is also going to include double steel tanks, plus extra deco tanks if you are doing deco diving. Even without the deco tanks, a set of steel doubles will probably eliminate needing a weight belt. Flood the suit on top of that and you can see getting off the bottom is going to take some positive bouyancy. If you're wondering about flooded suits, just imagine you put a hole in your suit on the wreck.

My experience with this experiment at Dutch Springs, (fresh water) was a 50 lb wing would get me back to the surface, but I really had to fill the wing to do it. There did not seem to be a lot of excess capacity. I then tried an OMS 100 lb wing and it responded much better and felt like there was still room to do more if necessary, e.g. bring something or someone to the surface.

Now the numbers sound huge, but if you assume that these wings only lift about half what they say they do, everything sort of comes in line with what you would expect.

The best thing to do is go to a place like Dutch Springs and try using a few wings and see how they feel.

Edited by Geek, 27 July 2006 - 01:58 AM.

[drbill]

One of the reasons I dive wet even in water in the upper 40's is that I've seen too many buddies and other divers flood their dry suits. Most of my buddies are dive pros and it has happened to them (several returned to diving wet). One had hers flood on a dive in the Antarctic.

Diving wet I know I have permanent buoyancy and only need to drop some of my weight to increase it in an emergency.

[PerroneFord]

Divers in the south are often accused of not understanding their diving brethern in the northeast. To be fair, I have never done diving in the northeast, but have some friends who do. However, they seem to dive with a different set of gear than the more common NE Wreckers. In an effort to better understand the diving I'd like to ask a few questions. So if you don't mind, I have a few itemized questions for you.


1. Did you happen to test your wing lift by actually using weights? I am aware some manufacturers under or overrate their wings. I was just wondering if you had tested yours.

2. On a dive to say, 120ft, what "stuff" do you carry? Can you offer an itemized list of things you take with you.

3. What is your exposure suit, and undergarment for the "average NE wreck dive".

4. What is your average run time on a NE Wreck Dive. Here the boats tend to limit us to about an hour.

5. When you dive, are you taking things off wrecks and if so, do you bring a lift bag for them?

6. Lastly, why do feel you need large steel tanks for doing a wreck dive in what is essentially, very close to recreational depths? I would think, perhaps foolishly, that a set of Aluminum 80s would be far preferable for ocean dives. I know that's what I am taking to the Oriskany.

Thanks

As one who actually dives here in the NE, I would like to add a few thoughts:

First, I don't believe the numbers that manufacturers claim. They're useful only in telling you that a higher number lifts more than a lower number, not in telling you the actual number of pounds of lift.

Having said that, NE diving is mostly wrecks on a hard bottom. I don't think you need to worry about walls locally, so what you really need is enough lift to get you and your stuff off the bottom with your drysuit flooded, early in the dive while the tanks are still full, and therefore negative. Your stuff is going to include a backup of just about everything because the visibility stinks and if you drop it, you'll probably never see it again.

Your stuff is also going to include double steel tanks, plus extra deco tanks if you are doing deco diving. Even without the deco tanks, a set of steel doubles will probably eliminate needing a weight belt. Flood the suit on top of that and you can see getting off the bottom is going to take some positive bouyancy. If you're wondering about flooded suits, just imagine you put a hole in your suit on the wreck.

My experience with this experiment at Dutch Springs, (fresh water) was a 50 lb wing would get me back to the surface, but I really had to fill the wing to do it. There did not seem to be a lot of excess capacity. I then tried an OMS 100 lb wing and it responded much better and felt like there was still room to do more if necessary, e.g. bring something or someone to the surface.

Now the numbers sound huge, but if you assume that these wings only lift about half what they say they do, everything sort of comes in line with what you would expect.

The best thing to do is go to a place like Dutch Springs and try using a few wings and see how they feel.

[PerroneFord]

One of the reasons I dive wet even in water in the upper 40's is that I've seen too many buddies and other divers flood their dry suits. Most of my buddies are dive pros and it has happened to them (several returned to diving wet). One had hers flood on a dive in the Antarctic.

Diving wet I know I have permanent buoyancy and only need to drop some of my weight to increase it in an emergency.

DrBill, I will begin diving dry this fall. I've spoken to quite a number of divers who dive dry, and many have had flooded suits. What I am curious about, is why a flooded drysuit seems to constitue an emergency. How negative does it make you when you flood a suit?

In my case, I now dive with either a 45# or 60# wing. I know that I am approximately 10-15# negative in the water in my doubles. Does a flooded suit exceed the 30-45# extra buoyancy I might be carrying?

[ScubaDadMiami]

One of the reasons I dive wet even in water in the upper 40's is that I've seen too many buddies and other divers flood their dry suits. Most of my buddies are dive pros and it has happened to them (several returned to diving wet). One had hers flood on a dive in the Antarctic.

Diving wet I know I have permanent buoyancy and only need to drop some of my weight to increase it in an emergency.

DrBill, I will begin diving dry this fall. I've spoken to quite a number of divers who dive dry, and many have had flooded suits. What I am curious about, is why a flooded drysuit seems to constitue an emergency. How negative does it make you when you flood a suit?

In my case, I now dive with either a 45# or 60# wing. I know that I am approximately 10-15# negative in the water in my doubles. Does a flooded suit exceed the 30-45# extra buoyancy I might be carrying?

A flooded suit does not make you negative since the salt water itself is not doing anymore to you than it would if you were swimming in a bathing suit. However, since the undergarments worn trap some gas, creating a space of it between the body and the suit, which is in direct contact with the water, flooding the suit fills those spaces with water, removing that gas, and taking away any positive buoyancy that the gas spaces created. So, if you are wearing additional lead to overcome the positive buoyancy of the gas spaces, and those spaces go bye-bye, you are now very overweighted. That's the problem.

The remedies are simple (at least in theory). 1) Carry weight that can be ditched in case of a flooded suit. Then, the diver will not be overweighted. 2) Carry a wing that can offset the negative buoyancy of what can not be ditched by the diver. 3) Combinations of the first two.

Of course, when the diver gets to the surface and then tries to climb out of the water, for every cubic foot of water in the suit, that adds another 64 pounds (based on salt water) of weight that the diver must lift out. Remedy? Simple: get dive boats to start using those diver lifts (instead of ladders) like they do in Europe and other parts of the world.

[PerroneFord]

So, if you are wearing additional lead to overcome the positive buoyancy of the gas spaces, and those spaces go bye-bye, you are now very overweighted. That's the problem.

Can you define "very overweighted"? When you flood your loop, you are flooding a defined volume of space and we can certainly give a weight to that volume of water. Can we do the same with the displaced trapped air held in by a drysuit? Is it 10#, 30#, 100#???