Diving without a buoyancy compensator

[kanonfodr]

Forgive me if I post this in the wrong forum, I just figured that you vintage guys would know this subject the best.

Is there a secret to diving without using a bouyancy compensator?? Most of the time we weight ourselves as to hold our last stop with our tank nearly empty, and use the BC to compensate for the weight of the gas we start with. Am I correct in assuming that, diving without a BC, you would weight yourself at half-tank and use your lung volume to make up the difference (ie breathing deeper with a fuller tank, breathing shallower with an emptier tank??)

Also, does planned depth factor into the equation, to account for increased loss of wetsuit bouyancy for deeper dives?

Finally, I know that LP72s were the de facto tank back in the day, due to the fact that they were neutral when empty. My LP85s are super similar in bouyancy characteristics, would these tanks work?

Appreciate the info.

Peace,
Greg

 

[herman]

My favorite way to dive.
It all about weighting. In general I weight so I am dead on neutral with 1/2 pressure in my tank. For an 80 cf that means I have to deal with +/- 2 lbs of swing which is easily in the range I can handle with lung volume alone. Tank type is not really an issue, use whatever works for you. I use AL-80s in fresh water for a couple of reasons. First off, I have them but mainly they happen to be the correct buoyancy for my needs. I dive no weights in fresh water with an AL and the weighting is perfect. If I switch to a steel 72 I am overweighted and with no extra weights I can ditch I have to either add an unneeded wetsuit, deal with the excessive weight with lung volume or put on a BC...all of which are a PITA. In salt water the 72s are about perfect if I do not add additional weight, otherwise with my AL-80s I need to add a few pounds.
You do have to factor in wetsuit compression and depth. Most old wetsuits compressed less than their modern counterparts so it is easier in them. If you intend to dive without a BC often and need a wetsuit, investing in one made of Rubatex (the old material of choice) is a good idea. There are makers of custom wetsuits that still make them in the old material....and style if you want. There are 2 basic way to handle wetsuit compression. You can weight for neutral at depth and swim it down or weight for the surface and drop weights at depth. Weighting for depth requires you to swim down your rig until compression is great enough that you can handle the remaining positive buoyancy with lung volume, usually at 10 to 15 ft you are within the easy range of lung volume control. This takes less weight but has the disadvantage of you being a good bit positive near the surface making safety stops very difficult. They were not done back in the day so no one worried about being positive....not a good option IMO unless your dives are very shallow. The other option is to weight for neutral the surface and carry removable weights. You start your decent as normal but be aware that you will become more negative as you decend. Once at the bottom, you remove some weight, dive and retrive it for the return to the surface. This method also requires you return to your entry spot which at times is not an option. And you must be prepaired for an accent without the extra weight in the event you miss your exit point or someone finds your "lost" weights. All in all I prefer the swim down method.
Which method I use depends on the wetsuit. If it's not a huge swing, ie within the range I can easily control it with lung volume, I prefer to weight for the bottom and swim it down. Esp if the dives are shallow where making a safety stop is not a big concern. Othewise I use the weight drop method but frankly once it gets to that level, I just put the BC back on unless there is a need to not have a BC, a full vintage for a photo shoot for example.

 

[Indian Valley Scuba]

Well spoken Herman, I started diving in '79 and we did not use BCD's at all when I started, just horsecollar safety vests with CO2 cartridges to use in case of emergency. Within a few years they added the inflator connection to your tank so you could actually use your BCD like we do today.

 

[Nemrod]

Forgive me if I post this in the wrong forum, I just figured that you vintage guys would know this subject the best.

Is there a secret to diving without using a buoyancy compensator?? Most of the time we weight ourselves as to hold our last stop with our tank nearly empty, and use the BC to compensate for the weight of the gas we start with. Am I correct in assuming that, diving without a BC, you would weight yourself at half-tank and use your lung volume to make up the difference (ie breathing deeper with a fuller tank, breathing shallower with an emptier tank??)

Also, does planned depth factor into the equation, to account for increased loss of wetsuit buoyancy for deeper dives?

Finally, I know that LP72s were the de facto tank back in the day, due to the fact that they were neutral when empty. My LP85s are super similar in bouyancy characteristics, would these tanks work?

Appreciate the info.

Peace,
Greg

If you have the Faber LP85, the one that is 7.0 inches diameter it should work, I have two of them and have used them without a BC. Not ideal but work OK.

I have a couple of vintage style wetsuits, both are made from Rubatex G231 and they do not shift buoyancy to the extent the modern soft, stretchy neoprenes do, they are also warmer.

The steel 72 is the best choice for no BC diving, an aluminum 80 works well for warm water no BC diving, no suit or minimal exposure wear.

I weight to be neutral at depth about half way through the dive. Yes, it is somewhat of a guess but most of us have been diving an awful long time and can usually get it right, close enough. Yes, you will be buoyant at the end of the dive, A.) safety stops were not used in the old days B.) I am able to hold my 15 foot stop.

I dive with a camera nearly 90% of the time, without a BC, since it is somewhat negative, it is part of my weight. I like to dive as if I had no BC even when I am using a wing, the wing, I suck it flat and never put any air in it often but with the camera, it is great, I can inject just enough air to neutralize my camera.

Modern divers tend to pant rather than breath with long, slow, somewhat deliberate cycle. It is much easier to use your lungs as a built in BC or to augment a BC if you have control over your breathing and use the full tidal volume of your lungs.

"Planned depth" is not really part of my consideration, most buoyancy shift from suit compression occurs in initial part of the dive, down to about 15 feet, beyond that the suit may continue to compress but the shift in buoyancy if much less. Yes, you have to swim the rig down to 15 feet or so, thus:

Swim down, swim around, swim back up.

Properly weighted, you will have to swim your rig down, you will be somewhat negative initially once below 15 feet or so but not excessive and controlled with your breathing, about half way through the dive you will be neutral and as you begin your ascent, yes, you will be slightly positive. Consider that neoprene has a recovery period, it will not completely regain it's pre-dive buoyancy, by the time your safety stop is completed, the suit will have recovered somewhat more, you will be down to 500 psi perhaps and you should be positive on the surface. This aids your return to shore or boat. Consider than many old school divers do use a snorkel for surface swims, face down, that shore diving was nearly always accompanied by a surface float. Should the no BC diver become fatigued or for whatever reason has an "extended" surface swim, he can drop his weight becoming even more buoyant. Note I said we usually had a surface float such as an inner tube, surfboard, 13 foot Boston Whaler etc.

N

 

[Greg Barlow]

Two of my close friends and I just completed a dive trip to the St. Lawrence Seaway. When making dives shallower than around 80ffw, I didn't wear a BCD, and weighted myself accordingly. As has already been explained, your buoyancy should be neutral with a half-empty cylinder.

However, with the deeper dives, I wore a modern BP and Dive Rite Venture wing. One of my buddies simply removed his weight belt and stowed it on the wreck that we were diving. Prior to everyone entering the water, he explained to everyone on the boat what he was doing so that none of them would "find" a lost weight belt. I have used the same technique a number of times.

For dives like the upcoming Portage Quarry "Legends of Diving" event, I will be using 4 lbs. with my Bare 5/4mm suit. Using a steel 72, it allows me to make a safety stop, and maintain correct trim throughout the dive.

I once had a DM tell me that it was "impossible" to maintain correct buoyancy without a buoyancy compensator. I politely thanked him and let him know that I would tell my vintage dive buddies that we have been performing modern miracles for many years.

Here are a few pictures from our trip.

Greg Barlow

 

[Mike Boswell]

I grew up diving on Oahu and never used a wetsuit or a BC. Nothing beats the freedom of swimming without the gear you need for cold water. If my memory is correct I needed 4 lbs of lead with my steel 72 and Hawaiian-type backpack.

 

[kanonfodr]

Appreciate all the info, guys. I'm gonna ease into it slowly by keeping my wing on my backplate (it's still great for sitting on the surface) but disconnected from the first stage. Luckily we have lots of accessible shallow shore diving here so I don't think I will be in too much danger, but this sounds like a lot of fun. I also have a feeling that, if I can get the hang of it, this could really improve my diving (okay, I know it's gonna hamper my diving at first). I'll let y'all know how it goes.

Peace,
Greg

 

[herman]

.................................................I once had a DM tell me that it was "impossible" to maintain correct buoyancy without a buoyancy compensator. I politely thanked him and let him know that I would tell my vintage dive buddies that we have been performing modern miracles for many years.

My wife overheard an instructor telling his buddy that I could not dive that way...meaning it was not possible. Needless to say I enjoyed hanging around him showing how it was done..

Appreciate all the info, guys. I'm gonna ease into it slowly by keeping my wing on my backplate (it's still great for sitting on the surface) but disconnected from the first stage. Luckily we have lots of accessible shallow shore diving here so I don't think I will be in too much danger, but this sounds like a lot of fun. I also have a feeling that, if I can get the hang of it, this could really improve my diving (okay, I know it's gonna hamper my diving at first). I'll let y'all know how it goes.

Peace,
Greg

No need to not connect your BC, just deflate the BC all the way and try not to touch it during the dive. If you end up feeling like you just have to inflate some, you have the option. Once you get your weights correct you will be surprized how little you use your inflator even when you have it.

 

[elmer fudd]

I'm thinking that living in Hawaii you should have a big advantage when it comes to diving without a BC. I'm guessing that you're probably wearing a 3mm suit so there shouldn't be big swings in buoyancy depending on your depth. I'm wearing a 7mm with 12mm on my torso and that can be 20 lbs. of buoyancy shift at depth.

 

[spectrum]

Nothing beats the freedom of swimming without the gear you need for cold water.

That's the truth!

Even here in Maine at this time of the year fresh water is such that you can dive in trunks or a shorty as long as you respect the thermoclines. Diving without neoprene or a buoyant bladder is the closes thing to being a bird in flight. Other than finessing your lung volume to compensate for tank contents you can go up, down or stay virtually at will. Once you have done it a few times you use your BC with a whole new perspective.

Pete