Diving Safely Without A BC

[Altamira]

When I learned to dive back in the mid 60s, we were diving the springs in Missouri with a J valve steel 72, full 1/4" (now 7mil) wetsuit including hood, boots, mittens, weight belt with homemade lead weights, and no bcd or horse collar. I don't remember breathing any more abnormally then than now, except for the crappy regulators compared to what is available today. The big thing I remember is that hovering was a lot more difficult because all you had was your lungs to somewhat control buoyancy, and wound up finning if you did not want to sink, especially early in the dive.. We also had to swim up our weights, every time, no matter what depth you were diving. Personally, I did not think any of those issues were any big deal or dangerous--still don't.

 

[tbone1004]

normal tidal volume is around 0.5l or around 1lb. That is sitting on the couch watching tv. Diving with an AL80 monkey diving is not hard and I can easily go into the pool and bare tank breathe while hovering with an AL80 with no noticeable change in breathing habits. In scuba you take generally larger breaths than you do while sitting on the couch because your breathing rate should slow down, part of why your RMV is not the right term for air consumption.

Under normal resting circumstances, everyone has a consumption rate of roughly 0.5l/breath and 12-16 breaths/min. ish. That equates to roughly a 0.2-0.3cfm SAC rate. Obviously very few people breathe that little when diving, so for you to increase your breath from 0.5l to say 2l, you're perfectly fine.

 

[Hawkwood]

Current teaching is that it's unsafe to drive without a seatbelt. Some drivers nonetheless drive without a seatbelt, at least some of the time, either because they are vintage car enthusiasts or for reasons of simplicity.

Under what circumstances, if any, do you believe it is safe without a seatbelt?

Want to clarify who you are asking?

 

[LeadTurn_SD]

I looked. It is titled the "PADI Standard Safe Diving Practices Statement of Understanding." In rev 5/09, v. 2.0, paragraph 3 lists required equipment:

• Bc with power inflator
  
• SPG
• Alternate air source
• Dive computer or tables.

Yikes! Between 1976 and 2007 I cannot understand how I did not perish, based on that PADI statement .

We began diving without BC's, octo's and dive computers. I was the the high tech diver in my group: I had an SPG! The rest relied on J-valves. Well, I had a J-valve too... does that count as redundancy??

The best answer I can give regarding BC's and "safety" is it depends. If you have a LOT of buoyancy to compensate for due to a thick wetsuit, going to depth without a BC can get "sporty". I've done that, and at about 150 feet I found myself finning constantly to hold depth, which increased air consumption and I think a little CO2 loading (I remember a bit of a "dark narc" versus my usual "happy place narc").

And surface flotation is important... we wore "safety vests" that were orally inflated.

With a safety vest or strategy for getting "positive" on the surface in an emergeny, proper weighting, not-too-thick a wetsuit, and good skills.... no BC required. I still often forget to use my wing underwater. Old habits like using my lungs to compensate for being slightly negative die hard.

Best wishes.

 

[tbone1004]

**** I don't know how I didn't die last week with no power inflator hooked up, SPG's that I couldn't see, and no alternate air source or computer.... Granted I was quarry diving and threw a sidemount tank on my back without changing the regulators, but damn, i should be dead!

 

[redacted]

Under what circumstances, if any, do you believe it is safe without a seatbelt?

When there are no police to ticket you.

 

[fjpatrum]

I've done this a couple of times. I rarely put air in my BC until I hit about 40 foot depth anyway, (especially with a thicker wetsuit), so anything above that depth is no different diving with or without. The one or two times I went deeper than that I compensated mostly with finning and didn't try to hover as much. If I'm being totally honest I probably did some hand sculling too but I don't remember for certain. I could still do some depth control with breathing but, honestly, I don't think on most dives I need to stop constantly so finning enough to stay in relative trim and at the depth I wanted wasn't significantly more work than just doing the dive. I think max depth was about 55-60 feet doing that.

For the record all of these dives were with AL80s and a steel backplate. Water temps varied from mid 40s up to mid 70s and exposure protection was wetsuits from 4/3mm full suit to 12-14 mm layered suits.

EDIT: To answer the specific questions...

Skills or knowledge to undertake this kind of diving safely:
1) Recognize panic and know how to deal with it, in yourself and your buddy.
2) Understand the buoyancy characteristics of your exposure protection.
3) Know how your breathing affects your buoyancy and the limits of those effects.

Specific circumstances where it is safe:
1) For me, any dive 40 feet depth or less regardless of conditions
2) Any dive with a hard bottom of 60 feet or less in benign conditions-- quarry, protected reef or something similar.
3) A dive where my buddy understands the ramifications and is comfortable with the choice.

 

[2airishuman]

Current teaching is that it's unsafe to drive without a seatbelt. Some drivers nonetheless drive without a seatbelt, at least some of the time, either because they are vintage car enthusiasts or for reasons of simplicity.

Under what circumstances, if any, do you believe it is safe without a seatbelt?

Storker

I asked a serious question about diving without a BC. Replies so far have included genuine information about the kinds of dives the respective posters consider safe without a BC, with particular focus on: wetsuit thickness, tank capacity, and depth. I would like to read more of these insightful replies. There have also been some opinions posted on whether diving without a BC is unsafe, and I welcome these posts also, although they would be more insightful if they were more detailed as to rationale or statistics.

None of this has anything to do with seatbelts, and I am frankly confused as to what point you're trying to make. Seatbelts are effective at reducing the severity of injuries when an accident occurs, and I do not see what parallels you're trying to draw between that and a BC, whose purpose could not be more different.

 

[tbone1004]

this has nothing to do with seatbelts, bad analogy because seatbelts do not impact the safety of your driving or the way you drive, they impact your safety when you crash. BCD's are a tool that is used to make diving easier, and possible under certain circumstances.

To reiterate. BCD's are buoyancy compensation devices. What needs to be compensated for? It accounts for the loss of negative buoyancy by the gas volume that is exhaled during the course of the dive, which in a cave dive can exceed 40lbs. It also compensates for the loss of positive buoyancy attributed by compression at depth of closed cell, flexible wall vessels *i.e. neoprene*. When the combined extremes exceed the comfortable capacity of your lugs, which is dependent on the specific individual, you need that tool to compensate.
In the early days of cave diving this was done by cutting the neck of a clorox bottle off and holding it in front of you and exhaling into it basically acting as a lift bag. Now it is done with a myriad of different BCD designs.

Now, surface safety/comfort is a different thing altogether and something the equipment manufacturers are very clear about putting on their bcd's. They are NOT personal flotation devices, we use them like PFD's, but they are not.

If you are diving in a bathing suit with an AL80, in clear sunny florida, do you need a BCD? For normal sized people, no way because the bcd doesn't need to compensate for a whole lot and as long as you are weighted properly, it's a non-issue. For the examples brought up above where you can't hover because you're too negative, well that's for you to decide if that is a tool that you need. I personally won't dive in anything more than a shorty without a BCD, but in swim trunks I have no problem diving with an AL80 in fresh or LP72 in salt with no bcd

 

[ronscuba]

.....

If you are diving in a bathing suit with an AL80, in clear sunny florida, do you need a BCD? For normal sized people, no way because the bcd doesn't need to compensate for a whole lot and as long as you are weighted properly, it's a non-issue. For the examples brought up above where you can't hover because you're too negative, well that's for you to decide if that is a tool that you need. I personally won't dive in anything more than a shorty without a BCD, but in swim trunks I have no problem diving with an AL80 in fresh or LP72 in salt with no bcd

I put in a little air at the beginning of the dive to stay neutral when motionless, breathing relaxed without thought. I don't doubt I could do the whole dive w/o air in the wing, but I would have to increase the amount of air I keep in my lungs at the beginning of the dive. I might experiment with it on my next dive to see how easy I can adapt.

I shoot video, so being able to hover neutral while motionless is important.