OP
Texasguy
Contributor
I don't see any weights on this guy, I guess tank is heavy enough.
How to dive without a BC, what is a technique for good buoyancy during the dive?
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Rich Keller
Contributor
If you want to split the difference 3lb would be about right. If you have other tanks available with less of a spread between full and empty you would be better off using one of those. I usually do this on shallow shore dives with a Luxfer 30 cu/ft tank that is +1.2 empty and -1 full. The guy in the pic is not wearing a wetsuit so the only variable he has to deal with is the tank.
It's mostly in the lungs. ....And not much for exposure protection.
For example, something we do a lot of in the tropics is "Monkey Diving", which is using a simple scooter harness & a stage bottle - no wing or BC.
As you can see, this aluminum 80 will suffer from weight swing over the dive. And, as you descend, the wet suit will crush, losing buoyancy, too.
The answer is careful weighting. I am picky about my weighting to the extent I will adjust by a half a pound if I need to. I adjust my weight so that I'm neutral, at the end of the dive, at 1/3 lung volume at 10' (insert asterisk).
The rest is simply lung compensation, which is like riding a bicycle. It works well enough that you can easily hold buoyancy and trim at 40':
This is all with skimpy (3 mil) exposure protection, which we can easily dive in this fashion down to 90'. If I'm wearing a 5 mil, I can do it, but need to have a max depth of about 60', or else I'll need a wing of some kind deeper. And of course, monkey diving with a dry suit is diving with a BC of sorts:
The setpoints that seem to work well are to start out approximately 10 pounds positive. This about the weight of the human head, so, if you float with a "half lungfull" with the clavicles just being at water level, you'll be about right:
If you exhale completely, you should sink down into the water, but not go glug:
And, a full, deep breath should bring the shoulders up to water level:
With this, you'll need to kick a bit to get deeper than 5', after which the suit will crush a bit and life will be easy.
So, it's mostly in the lungs. And being smart with your weight(s) to begin with.
All the best, James
(Asterisk) this is not my normal weighting procedure for when wearing a wing, where I weight to be neutral at the surface with an empty tank.
For example, something we do a lot of in the tropics is "Monkey Diving", which is using a simple scooter harness & a stage bottle - no wing or BC.
As you can see, this aluminum 80 will suffer from weight swing over the dive. And, as you descend, the wet suit will crush, losing buoyancy, too.
The answer is careful weighting. I am picky about my weighting to the extent I will adjust by a half a pound if I need to. I adjust my weight so that I'm neutral, at the end of the dive, at 1/3 lung volume at 10' (insert asterisk).
The rest is simply lung compensation, which is like riding a bicycle. It works well enough that you can easily hold buoyancy and trim at 40':
This is all with skimpy (3 mil) exposure protection, which we can easily dive in this fashion down to 90'. If I'm wearing a 5 mil, I can do it, but need to have a max depth of about 60', or else I'll need a wing of some kind deeper. And of course, monkey diving with a dry suit is diving with a BC of sorts:
The setpoints that seem to work well are to start out approximately 10 pounds positive. This about the weight of the human head, so, if you float with a "half lungfull" with the clavicles just being at water level, you'll be about right:
If you exhale completely, you should sink down into the water, but not go glug:
And, a full, deep breath should bring the shoulders up to water level:
With this, you'll need to kick a bit to get deeper than 5', after which the suit will crush a bit and life will be easy.
So, it's mostly in the lungs. And being smart with your weight(s) to begin with.
All the best, James
(Asterisk) this is not my normal weighting procedure for when wearing a wing, where I weight to be neutral at the surface with an empty tank.
hah there's a whole site out there for this?!
I always called it Monkey diving because my buddy did... didn't know others did as well
---------- Post added August 8th, 2013 at 01:57 PM ----------
Here's my rig:
I didn't have it sitting in my bungee on this dive, so its hanging low from just chest clips. Usually its tucked up nice and tight al-la-sidemount.
It's homemade: few drings, custom rings and 4 pieces of webbing.
4lbs on the small of my back, single AL80 side mounted on either side (I prefer left side when diving this way)
If using a wetsuit, I use about 6ish, but usually have a can light on too for more weight.
You need to already have good buoyancy control and be very comfortable in the water. It's a VERY "free" feeling. If I'm not tech diving, I absolutely dive this way almost every time. It travels easy too, just wad it into a ball and toss it in with your regs. For buoyancy control, as someone mentioned above, it's just lung usage only.
Also, having the right tanks help too. I have a pair of AL80's (the one in my photos, and it's mate) that are neutral to positive which work well. I have another pair that are heavy to neutral, but they are too heavy when full, so I can't monkey dive with them as it takes too much work to stay afloat. Steels are out of the question for me, just too heavy with no lift. You may be able to use heavier tanks with just lung control, but I found you spend most of your time fully inhaled and wasting air to do this. So as close to neutral as possible is your ideal tank for doing this.
I have an old plastic back mount thing too that I've dove with before with no BC, but if I'm going to do that, I prefer my monkey harness.
Fdog.. I love the graphics on your scooter. I need to get some fun stuff on mine. My buddy's got radioactive symbols on his. It gets quite a few stares when cleaning it after a reef dive at the hotel beach pools LOL
OP
Texasguy
Contributor
What about pushing a tank forward with a hand (or hands) butt first?
What you need to do is talk to those of us who actually do it today, not those who "did it back then".
I dive sans BC often and dive with others who do as well. Contrary to what you may be told or think, it is actually fairly easy to do and perfect trim and bouyancy control are easy to achieve, IF you properly weight yourself and know how to properly use breath control. I can easily hold my own with anyone in a BC. With no or little wetsuit your bouyancy does not change with depth so there is no need for a BC since there is nothing (except gas use) to compensate for, with thick wetsuits is does become more difficult but still doable. The gas use is not difficult to handle with single tanks, the total shift of an 80 is about 4 lbs, the proper way to weight for that is about -2 at the start of the dive and dead on at half tank which will put you about +2 at the end of the dive. 2+/- is easy to handle with just breath control alone. With experience you can increase that amount a good bit, my upper limit is around 6 lbs but it's not fun. If you are properly weighted and not wearing much wetsuit even if you are wearing a BC you should not be adding/removing air to the BC and in effect are still diving with no BC. That is the way I suggest divers new to no BC diving start since that allows them to revert to the normal way they dive if things are not going to plan. Once you are properly weighted and have contol of your breathing, you will be be amazed at the freedom no BC diving is.
I dive sans BC often and dive with others who do as well. Contrary to what you may be told or think, it is actually fairly easy to do and perfect trim and bouyancy control are easy to achieve, IF you properly weight yourself and know how to properly use breath control. I can easily hold my own with anyone in a BC. With no or little wetsuit your bouyancy does not change with depth so there is no need for a BC since there is nothing (except gas use) to compensate for, with thick wetsuits is does become more difficult but still doable. The gas use is not difficult to handle with single tanks, the total shift of an 80 is about 4 lbs, the proper way to weight for that is about -2 at the start of the dive and dead on at half tank which will put you about +2 at the end of the dive. 2+/- is easy to handle with just breath control alone. With experience you can increase that amount a good bit, my upper limit is around 6 lbs but it's not fun. If you are properly weighted and not wearing much wetsuit even if you are wearing a BC you should not be adding/removing air to the BC and in effect are still diving with no BC. That is the way I suggest divers new to no BC diving start since that allows them to revert to the normal way they dive if things are not going to plan. Once you are properly weighted and have contol of your breathing, you will be be amazed at the freedom no BC diving is.
dfx
Contributor
Ah, a sidemount diver
DaleC
Contributor
Using the rig above, here's a video showing a dive with no BC. A 3/2 one piece with 3lb's of lead. The St72 is a very good tank for this sort of diving though I do the same with twin Al40's. As stated, the trick is to actually experiment by diving and removing lead until you hit the sweet spot. It's not that complicated.
[video=youtube;EJZA1WYQbdI]http://www.youtube.com/watch?
v=EJZA1WYQbdI&list=TLAO1kglucRq0[/video]
This video shows the dangers of BC less diving:
[video=youtube;QpsR3EBysg8]http://www.youtube.com/watch?v=QpsR3EBysg8&list=TLAO1kglucRq0[/video]
Using the homemade Brass and leather rig above I did this dive wearing a heavier pinnacle wetsuit. The backpack adds a fair bit of weight so there is no lead. My buddy is a little preoccupied because he is using his fancy pants camera for the first time.
[video=youtube;lYP1aM0g8lU]http://www.youtube.com/watch?v=lYP1aM0g8lU&list=TLAO1kglucRq0[/video]
I find adhering to a strictly horizontal plane to be somewhat artificial and instead seek a sense of buoyancy that allows me to adopt any position I want.
beanojones
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As the picture shows The key to diving without a BCD is to have no wetsuit.
Or to know the depth, and set the weights and the wetsuits loss of buoyancy to match.
I go with a stage setup on the tank, and a looped reg for mine so there are fewer danglies, and an actual handle on the tank.
It's also easier, and possibly safer, to do this slightly underweighted than it is slightly overweighted.
---------- Post added August 9th, 2013 at 03:00 AM ----------
It's mostly in the lungs. ....And not much for exposure protection.
.
Note: This diver is actually using bubble trapping in the moustache as a BCD. SO there is a BCD!
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