Diving without BCD?

[doctormike]

4) Divers back then tended to be finning almost constantly (if you watch footage of them) and tended to worry less about hitting the bottom (Pete "The Chairman" tells of his fins being sold as strong enough to withstand the reef)

Yeah, I have always wondered about this when no-BCD proponents talk about how freeing it is.

If you are accurately weighted, then you will be neutral at 15 feet at the end of your dive. At the beginning the dive, then, by definition you will be negatively buoyant by the amount equal to the loss of wetsuit buoyancy (which can be significant for a heavy suit), and the weight of the gas used in the dive (about 5 lbs for an AL80).

Maybe physics were different in the days of the giants? I mean, you WOULD be negatively buoyant during the dive, no matter what, and possibly by a significant amount. So to stay off the bottom, did you just hold a lot of gas in your lungs for most of the breath cycle and/or fin constantly? Or did you adjust weighting to not account for safety stops, and just plan on doing a buoyant ascent at the end of the dive?

Maybe I'm missing something? Can one of you no-BCD divers tell me how it is done?

 

[Scuba Lawyer]

Hey is that Alec Pierce in that photo? Where is his suit?

Yes, that is the one any only Alec! Mike Nelson often dove without a wetsuit. I keep telling Alec that as soon as he gets his body to look like Lloyd Bridges in his prime he can dive that way. He doesn't listen to me.

 

[johndiver999]

That’s a great picture.

 

[nolatom]

Is your dad's car an automatic, or stick shift? If the latter, then please stop reading.

If the former, you might point out that getting back into diving is a bit like (re-) learning to drive. Automatic (the BC) allows you to easily take care of changing buoyancy based on depth/suit compression/tank air remaining, so you can concentrate your mind and relearning-energy on the dive itself, rather than on having to physically compensate for being un-neutral during much of the dive. No clutch, gear-grinding, just enjoy the road..

Personally, I've always driven a stick. But I've always worn a BC.

However it goes, best wishes to you both.

 

[Scuba Lawyer]

Yeah, I have always wondered about this when no-BCD proponents talk about how freeing it is.

If you are accurately weighted, then you will be neutral at 15 feet at the end of your dive. At the beginning the dive, then, by definition you will be negatively buoyant by the amount equal to the loss of wetsuit buoyancy (which can be significant for a heavy suit), and the weight of the gas used in the dive (about 5 lbs for an AL80).

Maybe physics were different in the days of the giants? I mean, you WOULD be negatively buoyant during the dive, no matter what, and possibly by a significant amount. So to stay off the bottom, did you just hold a lot of gas in your lungs for most of the breath cycle and/or fin constantly? Or did you adjust weighting to not account for safety stops, and just plan on doing a buoyant ascent at the end of the dive?

Maybe I'm missing something? Can one of you no-BCD divers tell me how it is done?

Oh boy, where to start? First, I am neither physician nor physicist. Just a guy going on 52 years of diving who was initially trained to dive without a BC (or SPG for that matter).

I can only tell you how I dive without a BC, others may have different approaches and that's fine.

I don't dive without a BC on every dive. I do a pure vintage dive when I'm making one dive that day and my depth doesn't exceed 45 feet. Those are my criteria.

I use a single 71.2 cu.ft. steel tank or a set of steel 38s. The reason is that they are a few pounds negative at the start of the dive and essentially neutral at the end of the dive. For me, aluminium tanks (and some steel tanks) have too much of a bouyancy swing.

As for weighting while wearing a 5mm farmer john/jacket wetsuit I weight myself to be neutral on the surface (maybe just a tad positive but not by much). When I start the dive I pike dive and kick down a few feet until my suit compresses slightly and I am essentially neutral.

From there, as I descend, I control my neutrality by lung volume. It is an acquired skill but easily mastered. I can stay absolutely neutrally bouyant that way down to about 45 feet without moving my fins. After that depth, at least for me, my suit compresses too much and I find myself heavy and having to kick to stay off the bottom. Hence, my personal vintage dive depth limit. Above 45 feet I can hover all day without kicking.

At the end of the dive, and approaching the surface, yes, there is some slight positive bouyancy. But if weighted correctly, not much. Of course there was no such thing as a "safety stop" back in the day and with a 45 minute single dive to a max depth of 45 feet (with the majority of the dive much shallower especially off the beach), well I won't get into a micro bubble debate but so far no issues. That said, I'm still able to stay neutral at 10 feet and a safety stop is no problem. It's that last 10 feet that can go by rather quickly IF one is not weighted properly at the start of the dive. We were taught originally that as you filled your game bag with lobster, abalone and rock scallops during the dive it would off-set that positive bouyancy during the last few feet of ascent. My, how times have changed.

Don't know if I've answered your questions but that's how I, and many of my vintage diver friends do it. I certainly do not recommend diving without a BC until one has enough dive experience to be very comfortable in the water and then practice skills in confined water until you have them as second nature. My 2psi, Mark

 

[Bob DBF]

Maybe physics were different in the days of the giants? I mean, you WOULD be negatively buoyant during the dive, no matter what, and possibly by a significant amount. So to stay off the bottom, did you just hold a lot of gas in your lungs for most of the breath cycle and/or fin constantly? Or did you adjust weighting to not account for safety stops, and just plan on doing a buoyant ascent at the end of the dive?

Yes you would be negatively buoyant, in the 5# range as the old steel 72 was the predominate tank of the day when I started in '62. Before that 50's and smaller, with lower service pressures, were used so the buoyancy swing was less. In other words, I would not dive my Faber 120 without a BC.

All of the above. To stay off the bottom, I used my lungs and and trim at an angle that gave me lift as well as propulsion. Since I was always exploring, to this day, constantly finning didn't seem to be a problem. At times, when deep enough, I would leave the weight belt and pick it up on the way back to mitigate the negative buoyancy at greater depths.

At the time the standard ascent rate was 60'/min, and no safety stop was necessary, actually it still isn't, however I was taught to weight to be neutral at around 15' so that I was able to hold deco stops at 20' and/or 10' with my lungs if necessary.

A weight belt was used, and could be ditched for increasing buoyancy. At times I wore a Mae West, with a CO2 detonator or two for emergency surface buoyancy, it could be orally inflated through a modified tire valve, a real pita. It was a life vest, think snorkel vest, not a BC. On later models, the valve was changed to a mouthpiece similar to a BC now, and eventually had a LP hose attached to make a Horsecollar BC.

It's not for everybody, so dive the way you choose. However it can be done safely using proper techniques which you can learn from geezers or freedivers.



Bob

 

[Jonny Wishbone]

I learned to dive in 1979 back when people did things they shouldn't have done and did not get as bashed as they do today, meaning I did not get certified until mid 80's but I think I was in good hands as I am still alive. I don't think we ever got past 40 feet either. I learned to dive with out a BC or a wet suit for that matter. We used J valves and I don't ever remember having an SPG. I do remember the first regulator I ever used was a US Divers Aquarius. There were no additional second stages used either, just the one in your mouth. The things we did "back in the day" would never be accepted today.

 

[doctormike]

Oh boy, where to start? First, I am neither physician nor physicist. Just a guy going on 52 years of diving who was initially trained to dive without a BC (or SPG for that matter).

I can only tell you how I dive without a BC, others may have different approaches and that's fine.

I don't dive without a BC on every dive. I do a pure vintage dive when I'm making one dive that day and my depth doesn't exceed 45 feet. Those are my criteria.

I use a single 71.2 cu.ft. steel tank or a set of steel 38s. The reason is that they are a few pounds negative at the start of the dive and essentially neutral at the end of the dive. For me, aluminium tanks (and some steel tanks) have too much of a bouyancy swing.

As for weighting while wearing a 5mm farmer john/jacket wetsuit I weight myself to be neutral on the surface (maybe just a tad positive but not by much). When I start the dive I pike dive and kick down a few feet until my suit compresses slightly and I am essentially neutral.

From there, as I descend, I control my neutrality by lung volume. It is an acquired skill but easily mastered. I can stay absolutely neutrally bouyant that way down to about 45 feet without moving my fins. After that depth, at least for me, my suit compresses too much and I find myself heavy and having to kick to stay off the bottom. Hence, my personal vintage dive depth limit. Above 45 feet I can hover all day without kicking.

At the end of the dive, and approaching the surface, yes, there is some slight positive bouyancy. But if weighted correctly, not much. Of course there was no such thing as a "safety stop" back in the day and with a 45 minute single dive to a max depth of 45 feet (with the majority of the dive much shallower especially off the beach), well I won't get into a micro bubble debate but so far no issues. That said, I'm still able to stay neutral at 10 feet and a safety stop is no problem. It's that last 10 feet that can go by rather quickly IF one is not weighted properly at the start of the dive. We were taught originally that as you filled your game bag with lobster, abalone and rock scallops during the dive it would off-set that positive bouyancy during the last few feet of ascent. My, how times have changed.

Don't know if I've answered your questions but that's how I, and many of my vintage diver friends do it. I certainly do not recommend diving without a BC until one has enough dive experience to be very comfortable in the water and then practice skills in confined water until you have them as second nature. My 2psi, Mark

Thanks, that's helpful! I guess it's a combination of limiting depth (and therefore exposure suit compression), not having a safety stop (so no need to be completely neutral at 15 feet), and better breathing compensation (more time with fuller lungs). I'm sure that like any other skill, it gets better with practice.

Just wanted to point out one common misconception. You said: "For me, aluminium tanks (and some steel tanks) have too much of a bouyancy swing."

Apart from suit compression, the only thing that changes during a dive is the gas that you consume, so the difference in the buoyancy is just that - the weight of that gas. Whether you dive with steel double 119s or a single fiberglass 3 liter tank, the buoyancy swing is the same. Your total ballast needed to stay at depth is what it is. Whether that ballast is from a steel backplate, a tank, ditchable pouches, trim weights, a weight belt or anything else just determines how that ballast is distributed. If you are diving in a bathing suit only and are overweighted with a steel tank and no additional weight, then you need a less negative tank. But buoyancy swing is not related to tank composition.

 

[2airishuman]

Can you dive without a BC - is it OK/do-able or is it suicide?

It can be done; I do it occasionally mainly to minimize size of kit in extremely remote areas.

I would not recommend it for inexperienced divers or those whose skills may be out of date. Part of the problem is that present-day instruction does not cover the unique skills necessary with this configuration. A present-day instructor will not, for example, tell you that it is useful to pick up a rock or two towards the end of your dive to maintain neutral buoyancy.

And part of the problem is that it can add risk to a dive, because it puts greater physical demands on the diver and offers fewer alternatives for staying at the surface following an emergency. Generally, there was greater emphasis on swimming ability and physical fitness during the pre-BC diving era.

He has some vintage gear that could be serviced OK - Conshelf XI and Calipso ?? regs. Tanks are out of spec (all gear is circa 1970s) but not too much to hire.

The Calypso regulator would have to be serviced and adapted to a modern configuration. You would add another second stage to it and a BC inflator hose. The location of the outlet ports on the Calypso is such that a 90 degree adapter is necessary for the BC hose. Those are available and it's no big deal to add one. There was a recall on Calypsos ages ago because the seat could come loose -- a spiral shaped retainer has to be added. Parts are still available of the recall work was not performed, as are service kits, Vintage Double Hose is one source. Plan on replacing the hoses, mouthpieces, and probably the SPG. They're good regs, so it's worth it.

The Conshelf XI first stage has only two LP outlets and therefore cannot be used for diving with a modern configuration. I have a Conshelf XII that I use as a tire inflator, which is about all they're good for now. If you decide to use this gear, I would recommend scrapping the Conshelf XI first stage and repurposing the second stage connected to it as a secondary for the Calypso.

He doesn't have a BC. He never has - I don't believe they were invented back then. He just has a bracket with straps that holds the tank to your back. As far as he's concerned it's all he needs and all he uses. But I'm a little nervous of diving with him if there's no way to get him to the surface. So is it a really bad idea, or is it OK?

(For context, my dad also reckons the dive is over when you can't suck air any more LOL).

If you want to dive safely, you should both use modern gear configurations and dive within the limitations that are now being taught. He should take a refresher course and you should take the open-water diver course.

At some point after you become accomplished divers you could consider exploring vintage gear for reasons of nostalgia, history, or whatever. The people who dive vintage gear today are accomplished divers who dive that way by choice, not because it's cheap.

 

[mcohen1021]

Hey all,

Can you dive without a BC - is it OK/do-able or is it suicide?

I guess this is mostly for the guys who've been diving since the 70s (if they're on the interwebs?). As a bit of background, I'm 40, and just got into diving. I've always loved it but was unable (certified) until now due to previous medical condition. My father is 65, and has not dove for a long time, but wants to get back into it with me. I would love that to happen but funds are very limited for both of us.

He has some vintage gear that could be serviced OK - Conshelf XI and Calipso ?? regs. Tanks are out of spec (all gear is circa 1970s) but not too much to hire.

He doesn't have a BC. He never has - I don't believe they were invented back then. He just has a bracket with straps that holds the tank to your back. As far as he's concerned it's all he needs and all he uses. But I'm a little nervous of diving with him if there's no way to get him to the surface. So is it a really bad idea, or is it OK?

(For context, my dad also reckons the dive is over when you can't suck air any more LOL).

Thanks!

gear is cheap. your life is not.

consider this thread closed with my advice - buy new gear.