Equipment for Solo Diving

[wedivebc]

30cu ft toascend from a 15' dive off the shore of lake huron? To ascend from a 40 ft quarry dive?

What you need depends on the dive you are doing. A lot of arguments about equipment - and about solo diving generally- lose sight of that.

I agree.
Let's say we ascend at 33ft/min from 130ft (5ata) and do a 3 minute safety stop at 15ft (1.5 ata) A normal experienced diver who consumes .6 cuft/min sac rate:
average depth 2.5 ata
asc time = 130/33 = 4min
asc gas needed 4min * 2.5ata * .6cuft = 6cuft
safety stop gas needed = 3 * 1.5 * .6 = 2.7
total gas needed for very conservative ascent = 6+2.7=8.7 cuft
13 cuft - 8.7 cuft = 4.3 cu redundancy

So it seems many divers could do a very safe ascent and still observe the rule of thirds with a 13cuft from 130ft.

 

[mempilot]

Not to put a damper on things here, but I think it is time for a reality check of sorts. Many of the configurations suggested do not really meet the redundancy requirements of solo diving.

Only slightly better are divers who are using H valves. H or Y valves provide no insurance against blown neck o-rings, burst discs, etc where the leak cannot be stopped or isolated. They also require prompt action by the diver to identify and shut down the offending regulator in the event of a free flow. That reuires a good deal of proficiency, training and ongoing practice - more than just seeing if you can reach your valves. Even with good skills and technique, you are only working with a single tank and far less volume, so any air loss in the time it takes to shut of the offending reg is far more critical than with doubles.

Training and experience issues aside, if you do not have the proper equiment to solo dive, you should not be solo diving. Period.

First of all, solo diving is not some regulated thing that has requirements. Good judgment is needed however. Name one incident of a blown neck o-ring underwater. This usually happens after visual when the valve is put on carelessly and it leaks or goes during the fill. A leaking tank neck o-ring can be identified in the predive check. A burst disk blowing underwater? Again I ask, when does this happen? Burst disks go when the pressure in the tank rises above the burst pressure. Since when does pressure in a tank increase during a dive? This also happens during a fill or when sitting on the dock, boat, or car when the tank is heated. If it didn't blow before the dive, it is not going to blow during the dive. Based on this, how is the h-valve not a good solution? The reg is what often fails or leaks. An h will do everything a set of double will do with the exception of the tank valve o-ring. Not being able to isolate during a deco/overhead dive would really be bad, but not on a recreational solo dive. What is your math for a free flowing reg on a recreational standard 80 or 100? How long till empty? No deco obligation right?

I dive solo all the time with either doubles or single with h-valves. The doubles are used for gas volume, and the valve is not the biggest concern here. Remember we're talking solo rec dives, not deco/overhead. A CESA can be performed from 60', so if my reg start leaking at 120, I start an ascent to 60 where I can perform a CESA from there if needed. How long does it take you to go from 120 to 60, 1 to 2 minutes? You'd be having a really bad day if your tank lost all it's volume in that time.

Just remember, your chances to getting in a fatal car accident within 1 mile of your house are much higher than a tank valve o-ring or burst disk going underwater. Do you wear two seatbelts when you drive?

 

[mempilot]

People are involved in situations everyday that have a higher accident rate than diving, but they don't take 1/100th of the precautions. In diving, we seem to have taken the precautions, so we now have to weigh the risk with reward. That is a personal decision. How much risk, for how much reward.

You have the chance of a blowout at 65mph. Do you have runflat tires on your car with stiff sidewalls to handle this, or do you have standard soft sidewall tires for comfort? It makes a big difference in handling, but the drawback is comfort. Risk and reward. But I doubt there is a thread anywhere on the internet denouncing drivers with big touring tires on their cars do to the impending safety hazzard in the event of a blowout at 65mph.

Sometimes we tend to overdramatize things to make up for our discomfort level. If I have two of everything, then I'll finally feel comfortable. Do that for a while and you'll start carrying three of everything.

There's nothing wrong with backups to backups, but I wouldn't tell someone otherwise if they made the decision based on their own comfort level with risk and reward.

 

[rjchandler]

I agree.
Let's say we ascend at 33ft/min from 130ft (5ata) and do a 3 minute safety stop at 15ft (1.5 ata) A normal experienced diver who consumes .6 cuft/min sac rate:
average depth 2.5 ata
asc time = 130/33 = 4min
asc gas needed 4min * 2.5ata * .6cuft = 6cuft
safety stop gas needed = 3 * 1.5 * .6 = 2.7
total gas needed for very conservative ascent = 6+2.7=8.7 cuft
13 cuft - 8.7 cuft = 4.3 cu redundancy

So it seems many divers could do a very safe ascent and still observe the rule of thirds with a 13cuft from 130ft.

OR :

3 cu ft from 130 to 99ft
2.4 for the next 33 ft
1.8 for the next 33
1.2 to the surface

that's 8.4

so an average diver can make it to the surface from 130 with a 13cu ft pony - but that is not planning

From 130, I am going to do a 5min safety stop. I could easily end up in deco at that depth so count on 5 - add on another
3 cu ft.(this is unplanned deco OOA ascent so we are not talking intermediate stops)

Already up to 11.4. What do i need to add for exertion, stress and delay in figgering out what is goin on?

Rule of thirds has nothing to do with this.

 

[mempilot]

OR :

Rule of thirds has nothing to do with this.

Maybe he wants to do some penetration on the way up?

 

[rjchandler]

Name one incident of a blown neck o-ring underwater. This usually happens after visual when the valve is put on carelessly and it leaks or goes during the fill. A leaking tank neck o-ring can be identified in the predive check. ?

The only time i saw it happen was at the end of a dive. a LOT of fizzy water. Don't know how long it would have taken to drain the tank. But the diver would not have been aware of it unless she became suspicious of the rate of drop on her SPG.

 

[mempilot]

The only time i saw it happen was at the end of a dive. a LOT of fizzy water. Don't know how long it would have taken to drain the tank. But the diver would not have been aware of it unless she became suspicious of the rate of drop on her SPG.

You can hear a leaking valve. You just have to be aware, which most divers aren't. There, I just blew my argument o-ring!

 

[HammerNoMore]

You can hear a leaking valve. You just have to be aware, which most divers aren't. There, I just blew my argument o-ring!

I'm guessing it sounds a lot like an extruded o-ring on an HP port. I've had that occur twice, once at 60' and once at the surface. In both cases I knew it immediatly.

James

 

[rjchandler]

harder to hear some of these things with a 5mil hood on.

of course, there is the clogged dip tube that DR BILL had (see the "41 yrs of diving.." thread in Accidents forum)H-valve wouldn't help that.

There's not a lot of easy answers on how to equip for these dives - only tradeoffs.

 

[mempilot]

There's not a lot of easy answers on how to equip for these dives - only tradeoffs.

Yep