Question on weighting for no BC diving

[aquacat8]

Well now that I have this vintage backpack, I’m thinking of trying it without the wing. My tank is a high-pressure steel 80 and I was definitely a bit too negative swimming around in a pool with it full with no wing, but I’m thinking it might be perfect in salt, however I realize I don’t really know how to weight myself for this kind of diving, and I’m seeking your kind advice my knowledgeable vintage diving friends.

Should I start the dive a bit negative?

I will be in either a dive skin or a three mil in salt,
I’m hoping I won’t have to go to an aluminum tank such as an aluminum 63.

I If I am in the springs I will be in seven mil. I don’t know if it is possible, due to buoyancy seesaw, to weight properly for no BC diving with such a thick wetsuit? I noticed in the old films they are mostly wearing either bathing suits or Rubatex which I understand did not compress as much as new neoprene

Chances are I will be solo although very shallow, so I’d really rather not be stuck to the bottom! On the other hand I’d like to be able to hold a safety stop, or be able to glide around just under the surface.

Your advice and experience is appreciated!

 

[Eric Sedletzky]

What water temps?
I’d wear a three mil if you’re going to use the steel 80 in warmer water. Those are pretty negative and you’d need the buoyancy of the suit to offset the heaviness of the tank. If you want to use no wetsuit or just a skin then I’d use an aluminum 80.
What you also have to realize is that vintage style no BC diving is not going to be as precise as having a wing and being able to control pinpoint buoyancy, but with practice you can get pretty close. The style will be entirely different, you’ll more closely resemble a freediver moving through the water in a straight line with your body aligned relative to your direction of travel. Hovering in a sky diver position with feet up is a BC thing, not a no BC thing.
As far as weighting, you’ll want to weight yourself so that you’ll be floating on the surface or just about neutral with a full tank, and you’ll have to tip forward and swim down. You’ll be swimming around using your lungs for buoyancy breathing deep breaths holding more air than usual but still doing complete cycles and not holding your breath at any point (duh obviously).
At the end of your dive when your tank has emptied out you’ll ultimately want to be able to rest at your 15’ stop perfectly and hold position with breath control alone. Personally, I tend to like to start getting light at the 20’ mark and I grab rocks if I need to or hold onto kelp, but that’s where I dive. I also use a much thicker wetsuit than you will be so I tend to weight lighter to give me more depth range, which is less than where you are. The thinner the suit the less weight swing with compression, and no wetsuit will give you the most depth range.
You’ll find that your weighting is going to be way less than when you use a BC. Your weighting is critical with no BC diving because you’ll have no device to cover for it. Start too light with weighting and add as needed, not the other way around. Bouncing off the bottom is no fun.
And remember, your safety mechanism to establish positive buoyacy is to drop your weights. There is no BC to use for floatation so dropping your belt was/is the standard default procedure to get positive. Make sure your belt goes over everything else.
Good luck! and have fun!

 

[aquacat8]

Thanks @Eric Sedletzky that is a lot of info! I would’ve thought to start about 3-4 pounds negative but I see how that could be a problem if you needed to stay up for some reason at the beginning. I don’t wear any weight with that tank wearing three mill and my wing in salt water so I’m not sure what to do about ditchable weight. I suspect that wing does trap some air too. Perhaps I really do need to pick up an aluminum 63.

Anyway It really sounds like a fun challenge, something I can do to play with my gear and feel like an old-school diver. I like the idea of swimming streamlined like a freediver! Even though my cave type Buddies just taught me to keep my feet up and do cave kicks it still feels funny to me and not streamlined at all. In fact the first time I saw divers swimming that way I thought what the heck are they doing and I thought it looked really amateurish LOL

 

[herman]

With little to no wet suit, I start weighted negative at half the value of the shift in a full tank with half full lungs. In other words for an AL80 I start around 2 lbs negative. This makes me dead on neutral at half a tank and about 2 lbs positive at the end of the dive. I can easily control 4 lbs either way off neutral with breath control only but prefer not to if I can, frankly it 's not a lot of fun, +/- 2 is easy. I vary my breathing to accomplish neutral throughout the dive. While overweighted, I breath deeply, pause and exhale less than a full breath with no pause during the exhale. When positive I reverse the procedure, deep slow exhales with a pause followed by a less deep, short inhale. At neutral it's a slow deep inhale followed by an equal exhale. I will disagree with Eric on one thing, I can easily hold the skydiver hover while diving with no BC. I do a lot of macro photography with no BC so it can be done.

 

[Blueringocto_73]

Just a thought unrelated to your question. You will be solo diving. Maybe an inflatable device to keep you buoyant should you run out of steam or get a leg cramp. You'll be finning non stop. I remember from when I was 16 years old doing it.

 

[aquacat8]

Good idea Blueringocto_73 about bringing some emergency buoyancy. I was thinking an SMB could be rested on like a pool noodle if tired on the surface, or used to help surface if something unforeseen happens. (Like when that big jelly stung me and I wondered if I would be able to swim!)

Thanks @herman for the weighting tips!

Even though I said solo I will probably be at BHB or Ginnie Springs which are always full of divers, or even with buddies. If it works well I may try it really solo at Lauderdale-by-the-Sea, still very shallow, with a close solid bottom. I really did notice I could bomb around like a real swimmer when I tried it briefly in the pool. That wing really does cause drag. I want to see if it really feels freer. I am already used to swimming an hour straight in Jet Fins and mask. If diving could just feel more like swimming!

I just don’t know anyone else interested in this type of diving. My buddies are very orthodox cave gear types and oddly not really big swimmers and certainly not freedivers. They like to have all the right gear like Shearwaters, mighty fine backplates, and so on, and I suspect think I’m a bit funny with my DIY Franken BC’s! On the other hand I shudder watching my buddy who is working on cave skills squeeze through tiny spaces while I go around!

 

[aquacat8]

Tell @herman why do you choose to do macro photography with no bc?

 

[captain]

I know it is blasphemy today but back in the day safety stops were unheard of and everyone used the old Navy tables with the 60 FPM accent rate. Being positive at the end of the dive was a plus. Using a 3/16" or 1/4 " wet suit I would have to kick to descend or pull down the anchor rope. Once suit compression kicked in usually around 30 feet then I could drift down and control buoyancy with breathing.

 

[aquacat8]

Interesting...

 

[herman]

I enjoy macro photography and I often dive with no BC ...and a double hose reg. No other reason.
A good way to start learning how to get yourself properly weighted and to practice without removing the BC is simply to drain ALL the air out of your BC and go dive. Don't use the BC but in the event you really need it, it's there as a back up until you get comfortable without it. You will find that once you get comfortable without a BC, you will tend to not use it even if you have it on. With proper weighting and breathing techniques it is not needed with warm water single tank diving.