Diving Dry? Balance your Rig!

[Darnold9999]

We are headed to the 10m pool this weekend to play with my buddy's weighting. I was planning to tinker slightly with mine, but for the most part am going to support his efforts. It had not occurred to me that I should probably test flood my suit at least once, and preferrably in the nice 30-c water. Any suggestions for this procedure?

Yes - don't do it. Your suit flooded will be neutral - have the same impact on your overall boyancy as a bathing suit. So wearing a bathing suit with the rest of your rig will be the same as a flooded dry suit. As Diver0001 says different story getting out of the water - 20 litres of water weighs nothing in the water and about 44 lb out of the water.

 

[tracydr]

One thing that will help,if diving without a redundant air supply,is to at least have a separate system for drysuit inflation. An Argon or separate inflation bottle would have allowed continued inflation in an OOA emergency.
Not that I currently am diving with argon,either but I've considered this option and understand why on bigger dives it would become more important.
The main reason you'd be using argon, of course,is that you don't want to be wasting expensive helium on your drysuit.

 

[Diver0001]

We are headed to the 10m pool this weekend to play with my buddy's weighting. I was planning to tinker slightly with mine, but for the most part am going to support his efforts. It had not occurred to me that I should probably test flood my suit at least once, and preferrably in the nice 30-c water. Any suggestions for this procedure? I know I should practice the way I dive, but I'd prefer not to have to drive 2 hours home with soaked undergarments bagged up in the car. Shouldn't be too different to flood the suit with just a swimsuit on, right? Better to do this through a wrist/neck seal or with the zipper? Also, how difficult is it going to be to exit the water? Should I be worried about tearing a seam with the weight of the water? The pool we are going to has a platform at the top that you can stand on, putting the water about chest deep. I suppose I can doff the suit there to mitigate the weight.

My opinion about this is that you should do these kinds of tests using the same gear that you use in open water. That would mean, full undergarment, all the same weights, lights, stage tanks or whatever else you normally use and then get your buddy to unzip your suit in *shallow* water. 10m is too deep. 2m with access to a pool-side ladder for plan B is better. These kinds of tests are best done in highly controlled circumstances for obvious reasons.

I think the insights you gain may be worth the drive home with wet stuff. Bring plastic bags

Another example:

A few years ago some of the wreck diving crew around here started doing "net training". It's something we initially developed by based on some ideas from a particular dive club that focused on North Sea wrecks which are often covered in debris, among other things, lost fishing nets.

Initially we did them using "pool" gear. No wetsuits, full foot fins and light gear. After a while it started to sink in that this isn't how people dive on wrecks and that when you're in pool gear you have a lot more mobility than you might in the real world.....so we started asking them to bring the whole kitchen sink that they usually dive with. Drysuits, dry gloves, open heel fins, lights, stages, knives, lift bags, spools, even hammers and chisels (don't judge, that's how some people wreck dive).... etc etc. We even put some of them in blinded out masks to simulate a silt out.

When fully entangled in a net with *that* gear on, it became a lot less trivial to get out of it... which also meant that the students learned a lot more from experiencing it in *highly controlled* circumstances. One of the most revealing discoveries? Fin buckles, knives attached to the legs and "A-clamps" are by far the biggest entanglement hazards. If we hadn't started doing these using full open water gear, we might not have realized that.

Hence the reason I say that when you do decide to experiment with failure modes that will only ever happen in open water that you should use exactly the same gear you would expect to be in when the poop starts to fly. Just make damned sure the conditions are fully controlled. If in doubt, don't mess around trying to figure it out. Get a professional with experience to help you set it up. We've had enough statistics and we don't need people drowning in pools while playing around with extreme failure modes.

R..

 

[nimoh]

One thing that will help,if diving without a redundant air supply,is to at least have a separate system for drysuit inflation. An Argon or separate inflation bottle would have allowed continued inflation in an OOA emergency.
Not that I currently am diving with argon,either but I've considered this option and understand why on bigger dives it would become more important.
The main reason you'd be using argon, of course,is that you don't want to be wasting expensive helium on your drysuit.

A typical argon inflation bottle is 6cuft, which amounts to a little over 200 psi in an aluminum 80, so not really a big difference. I think a diver would be better off with a pony bottle than an argon bottle in an out of gas emergency. However, proper gas planning along with redundancies to prevent the out of gas problem would be even better.

The main reason tec divers use argon bottles is not to save their expensive helium, but rather it is because they need a different gas in their suit since helium is a very poor insulator. A lot of divers use plain air in their inflation bottles, and many use argon since it is more dense and provides even better insulation. If the reason was to save on helium, they would be hooking up their BC to their inflation bottles as well.

 

[Diver0001]

The main reason you'd be using argon, of course,is that you don't want to be wasting expensive helium on your drysuit.

Argon conducts thermal energy a LOT slower than helium. The reason you don't use trimix in your suit is because if you did you'd freeze your butt off.

R..

 

[GrumpyOldGuy]

One thing that will help,if diving without a redundant air supply,is to at least have a separate system for drysuit inflation. An Argon or separate inflation bottle would have allowed continued inflation in an OOA emergency.
Not that I currently am diving with argon,either but I've considered this option and understand why on bigger dives it would become more important.
The main reason you'd be using argon, of course,is that you don't want to be wasting expensive helium on your drysuit.

You could of course just add a qd hose to a pony or stage bottle to accomplish this without futzing around with more gear. Still seems like planning for 2 independent failures (OOA and Wing) which is a reach for most of us.

 

[dive_turkey]

Yes - don't do it. Your suit flooded will be neutral - have the same impact on your overall boyancy as a bathing suit. So wearing a bathing suit with the rest of your rig will be the same as a flooded dry suit. As Diver0001 says different story getting out of the water - 20 litres of water weighs nothing in the water and about 44 lb out of the water.

This is what I had figured on buoyancy. However, I am also slightly concerned about the increased resistance of swimming up a flooded suit. I would think there to be an increased effort here to some degree.

My opinion about this is that you should do these kinds of tests using the same gear that you use in open water. That would mean, full undergarment, all the same weights, lights, stage tanks or whatever else you normally use and then get your buddy to unzip your suit in *shallow* water. 10m is too deep. 2m with access to a pool-side ladder for plan B is better. These kinds of tests are best done in highly controlled circumstances for obvious reasons.

I think the insights you gain may be worth the drive home with wet stuff. Bring plastic bags

Another example:

A few years ago some of the wreck diving crew around here started doing "net training". It's something we initially developed by based on some ideas from a particular dive club that focused on North Sea wrecks which are often covered in debris, among other things, lost fishing nets.

Initially we did them using "pool" gear. No wetsuits, full foot fins and light gear. After a while it started to sink in that this isn't how people dive on wrecks and that when you're in pool gear you have a lot more mobility than you might in the real world.....so we started asking them to bring the whole kitchen sink that they usually dive with. Drysuits, dry gloves, open heel fins, lights, stages, knives, lift bags, spools, even hammers and chisels (don't judge, that's how some people wreck dive).... etc etc. We even put some of them in blinded out masks to simulate a silt out.

When fully entangled in a net with *that* gear on, it became a lot less trivial to get out of it... which also meant that the students learned a lot more from experiencing it in *highly controlled* circumstances. One of the most revealing discoveries? Fin buckles, knives attached to the legs and "A-clamps" are by far the biggest entanglement hazards. If we hadn't started doing these using full open water gear, we might not have realized that.

Hence the reason I say that when you do decide to experiment with failure modes that will only ever happen in open water that you should use exactly the same gear you would expect to be in when the poop starts to fly. Just make damned sure the conditions are fully controlled. If in doubt, don't mess around trying to figure it out. Get a professional with experience to help you set it up. We've had enough statistics and we don't need people drowning in pools while playing around with extreme failure modes.

R..

I do agree with you here. The only part of my gear I was considering removing was the undergarments, hood, and gloves. We will be diving in 30 degree water and I'm pretty sure I'll die of heat exhaustion before drowning if I wore my halo 3D down there. I was planning to wear a simple set of long underwear to keep the trilam off my skin. It does occur to me that the hood and gloves being removed will aid in mobility and dexterity that I probably would not have if diving in cold water, but for safety I feel they should stay off in the pool session as well since it is the first time we would be attempting this. There will be no entanglements or other simulated gear failures.

 

[Diver0001]

I do agree with you here. The only part of my gear I was considering removing was the undergarments, hood, and gloves. We will be diving in 30 degree water and I'm pretty sure I'll die of heat exhaustion before drowning if I wore my halo 3D down there. I was planning to wear a simple set of long underwear to keep the trilam off my skin. It does occur to me that the hood and gloves being removed will aid in mobility and dexterity that I probably would not have if diving in cold water, but for safety I feel they should stay off in the pool session as well since it is the first time we would be attempting this. There will be no entanglements or other simulated gear failures.

Sounds like a responsible approach. Don't do it in 10m though. Do it with a hard bottom at 2-3m and access to a ladder.

R..

 

[mala]

This is what I had figured on buoyancy. However, I am also slightly concerned about the increased resistance of swimming up a flooded suit. I would think there to be an increased effort here to some degree.



I do agree with you here. The only part of my gear I was considering removing was the undergarments, hood, and gloves. We will be diving in 30 degree water and I'm pretty sure I'll die of heat exhaustion before drowning if I wore my halo 3D down there. I was planning to wear a simple set of long underwear to keep the trilam off my skin. It does occur to me that the hood and gloves being removed will aid in mobility and dexterity that I probably would not have if diving in cold water, but for safety I feel they should stay off in the pool session as well since it is the first time we would be attempting this. There will be no entanglements or other simulated gear failures.

buoyancy in a trilam comes from air in the suit ,air in the undergarments and the volume taken up by the undergarments.
a full flood in your skinnies will not give you the same buoyancy swing as in the full cold set up.

---------- Post added October 15th, 2013 at 05:53 PM ----------

Try this: Go in a pool. Flood your dry suit. Are you swimming up? How bout with your gear on?

There are risks to everything, Mitigating those risks are more important than fearing them.

Most dry suits, with a full BCD and all weights dropped will likely not bring you to the surface when full of water...(but I might be wrong on this)

a fully flooded neoprene suit will loose very little buoyancy-maybe 1kg.
a fully flooded trilam will loose a bit more-maybe 3kg depending on the fit/size undergarments etc.

at the end of the day the water on the inside weighs the same as the water on the outside.

 

[nimoh]

while I agree that a trilam suit full of water is neutral, it may not be the same as swimming up with no suit since it will have more drag, and will tend to restrict movement of arms and legs.