"Correct Weighting" Identified as #1 Needed Improvement in SCUBA Diving

[dmaziuk]

but you can add air to the drysuit for more buoyancy, so you do have a backup aircell of sorts you could use if things go titsup. In tropical shallow waters you can dive without any neoprene and without any ditchable weight, and then if you wanted to get lighter fast, you better grow very big lungs. Or learn to ditch your kit in 2 seconds flat.

 

[wetb4igetinthewater]

but you can add air to the drysuit for more buoyancy

That is true, but assuming there is no BCD, how fun is it to establish positive buoyancy at the surface, especially with a silicone neck seal?

 

[dmaziuk]

That is true, but assuming there is no BCD, how fun is it to establish positive buoyancy at the surface, especially with a silicone neck seal?

Right, but I was replying to the tropical shallow dives part. There was a link in one of the earlier "no bcd" threads to people lobster-diving in CA without BCDs -- thick wetsuits with plenty of lift and shallow dives without much suit compression. That I can see: ditch your weightbelt, and you'd need a heavy-ish one to sink the suit, and you're now plenty positively buoyant without an air bladder.

 

[JamesBon92007]

I'm with you on all counts, so far. Minnesota lakes pose some of the same problems.

I expect to be diving in Minnesota on or about July 5th. Somewhere around Marine on the St. Croix. I snorkeled there last year with no wetsuit so I'm only bringing my 2.5mm wetsuit. I may regret it. Last year you suggested I take my 1/4" Farmer John but I ended up not doing scuba on that trip. How much less weight do you think I will need as opposed to salt water?


Maybe you could try a BP+W. That's what I use, with a small wing when circumstances permit. The bulk and weight of your overall setup would not then be materially different than with just a tank. I know, I dive both ways.

Ah yes, I have been looking at them online and even the DIY versions. I can see how it could be very compact and how the backplate could add some weight in just the right place.


You could, you know, get a stainless steel backplate that weighs enough to offset the buoyancy of the AL80, and a compact 17# wing. People have done that. You can go out and buy that stuff. It isn't expensive.

It's not so much how much it costs but rather what am I getting for my money. I have an old backpack and a Mae West type vest and about all it needs is a power inflator attached (I'm experimenting with it). Somehow that does not add up to the $350+ I've seen them selling for. Ultimately my plan is to go with the backplate/wing setup but in the meantime I got a like-new BC for very, very little money so that will save me the rental fees plus I'll know where all of the buttons are. My girlfriend always takes a checked bag anyway so I'll just throw it in her luggage I've seen BCs renting for $18/day in some places!



Steel cylinders are inherently more expensive to make.

Faber LP85s are substantially identical to the old LP72s and could be seen as a modern version of them. You can even get galvanized ones now.

The price was part of the appeal when AL80s first became popular but they didn't live up to the longevity expectations. I doubt if many dive ops are looking 20-20 years into the future so it's unlikely they will be buying steel tanks by the dozens like the do the AL80s. But I did talk to one instructor who now has reservations about buying cheap tanks after someone he knew was killed filling a Chinese AL80.

I hope I didn't make a mess out of the quotes. :|

It turns out I did make a mess of the quotes so please "expand" to read my replies.

 

[JamesBon92007]

Now imagine that your truck can only go 1 mph but you can easily walk at 2. Now it's a perfect example.

Commercial truck drivers first learn to drive a basic car before moving up to an 18 wheeler. Commercial airline pilots learn stick and rudder skills in little planes that lack the all weather equipment, IFR instruments, autopilot, retractable gear, etc.... It makes sense to me to first learn scuba with the most basic equipment before piling on the specialty equipment, even if that specialty equipment can provide a capability to do other things like dive in bad weather and cold rough oceans, or carry big air for deep diving. The dive industry seems to think that it's just fine to not know the basics, as long as you can use the advanced equipment to fake your way through it. That would be like the FAA saying that a pilot can skip the stick and rudder skills, so long as you learn, train and fly in planes that are equipped with an autopilot.

Anyway, I've said my bit more than once and it does not appear that this is going anywhere. The current lot of instructors and training agencies seem to be set in their ways, and are too lazy and/or unmotivated to learn to do anything different. I imagine that 10 years from now, weight management will still be at the top of DAN's list of most needed improvements in scuba diving.

Peace and good diving everyone.

There have been many discussions here about the way diving is taught nowadays compared to what we lovingly call the "vintage" days and from what I've seen I believe that we were probably better trained in the sense that we conditioned to respond to various situations and possibly had a deeper understanding of our equipment, as limited as it was. The basic course (at least the one I took) seemed to cover a lot more than it does now and we were probably more prepared to take on more difficult situations that a typical OW graduate of today. We dove with a wristwatch, no BC, sometimes no depth gauge (shallow beach dives), no computer, dive tables, and sometimes a J-Valve. Do I think that this made me better prepared to work with the modern equipment and techniques? Hell yes.

 

[Neilwood]

I appreciate how weighting can be a contentious topic.

Weighting to be "perfect" would be difficult for me I reckon - my normal wetsuit at home is a 4XL 7mm steamer (required due to height as well as my slowly reducing girth). If I weight correctly at the surface (guessing about 1.5Kg/mm thickness due to the size) and allowing for compression at 20-30m depth to 2-3mm means I am now 6-7.5 Kg overweighted. Kind of hard to cope with that extent of a shift without having some means to compensate for it.

Despite all the input from @REVAN about how diving without a BCD is so good I have still not had the answer as to how to dive sans BCD with a 7mm wetsuit to depths of 20-30m. Heck even at 10m it is probably about 3-4kg of buoyancy lost which is getting in the realms of being hard to control with breathing alone for an extended period.

 

[JamesBon92007]

Despite all the input from @REVAN about how diving without a BCD is so good I have still not had the answer as to how to dive sans BCD with a 7mm wetsuit to depths of 20-30m. Heck even at 10m it is probably about 3-4kg of buoyancy lost which is getting in the realms of being hard to control with breathing alone for an extended period.

I've done it and while doing it it didn't occur to me that it was a problem. However, I was usually diving some place like Catalina (California) and was taking pictures so it was generally an advantage to be a little bit negative. If I rested on the sand or a rock momentarily I don't think I was damaging anything living and I'd usually just rest on a fin tip. If I was diving some place like Cozumel where there are lots of delicate sponges and corals etc I would prefer to have some kind of buoyancy compensation other than only my lungs and the inertia of moving forward. If I was inside a silty shipwreck I would not want even a fin tip to touch the bottom and stir things up. When I do dive deeper than about 40-50 feet without a BC I usually wear a flotation vest just in case I ever needed to drop my weights and didn't have enough buoyancy due to wetsuit compression. I've just never put any air in it.

My understanding of REVAN's point that he is trying to make is that diving without a BC is a skill that might actually help some divers achieve better buoyancy control while they are using a BC (or not). He is pointing out that not only is it possible, but under certain circumstances it is desirable and sometimes a BC is simply not necessary. I find his comments to be an appropriate response to DAN's #1 Needed Improvement.

 

[TMHeimer]

Despite all the input from @REVAN about how diving without a BCD is so good I have still not had the answer as to how to dive sans BCD with a 7mm wetsuit to depths of 20-30m. Heck even at 10m it is probably about 3-4kg of buoyancy lost which is getting in the realms of being hard to control with breathing alone for an extended period.

I see your point, as I mostly dive with 7 mil farmer john wetsuit and (always) AL80 tanks. I'm sure it can be done, but have no reason to try it and see. Imagine you'd do a lot of deep inhaling, exhaling and kicking (maybe some arm sculling?). Then if you got in trouble for some reason on the bottom and had to jettison weight you may cork and be in serious trouble if diving deep. But, they all used to do it--I just have no reason to.

 

[Colliam7]

I'm sure it can be done, but have no reason to try it and see.

Yes! And, that is one of the challenges of this thread: a potentially good idea - learning to maintain buoyancy without having to use your wing / BCD - was presented in a way - diving without a BCD - that has a number of inherent problems, including safety issues, and is simply not supportable, nor do reasonable people have any reason to try it and see.

I observe more than a few divers who appear to be entirely dependent on their BCD. They swim underwater, holding their power inflator in their hand, adding and purging air on a regular basis, apparently without trying to use their breathing to make buoyancy adjustments at depth. That is a very inefficient, completely unnecessary. and therefore truly unfortunate practice. I suspect the practice evolves for several reasons - a) using breathing to maintain buoyancy control is not given sufficient emphasis in OW training by some (a few) instructors, b) the time allocated to repetitive practice of buoyancy control techniques during some OW instruction is insufficient, AND c) far too many divers never practice any skill learned in OW again (my personal favorite).

The logical question would be, how do we address the development of proper weighting technique (the nominal topic of this thread), and good buoyancy control skills. But, a reasonable idea - that it would be a good training activity to have divers practice diving without using their BCD, at some point during their OW training, is unwisely presented in a simplistic and problematic manner:

I believe the most effective solution would be to return to old way where divers first learn to dive with a tank on a simple backplate (no BCD).

One of the functions that a BCD should perform is to float a diver's rig at the surface. Diving without one might tend to limit that functionality. There may be situations where a diver needs to surface early in a dive, when they are necessarily negatively buoyant (full cylinder) and having the extra buoyancy afforded by a BCD bladder would be useful (yes, if they are properly diving a balanced rig, they should be able to swim their rig to the surface, where they can. hmm, ditch it if needed to establish positive buoyancy). The value of having the flotation capacity of a BCD is well-established. Suggesting that we require students to first learn to dive without one is simply a non-starter, when a much better idea would be suggesting that we require students to learn to dive at some time without using one.

I am more chronologically gifted than many people on the Board, and than many people I dive with. By golly, I learned to type papers on a Royal mechanical typewriter (and I could change that ribbon on a metal spool). I had to use a rotary dial telephone, and we were on a party line. I grew up in an apartment without air conditioning, in a warm, humid coastal city. And, I learned to drive in a car with a 3-speed transmission, with a gear shift on the steering column. But, I am writing this post on my laptop (with no ribbon in sight), my only phone is a small, lightweight, mobile unit with virtual buttons, I value and routinely use A/C, and all of my cars and trucks have automatic transmissions. I feel no desire to go back to any of those things I grew up with, nor do I wistfully bore my children with stories of how I walked 5 miles to school and back each day, uphill in both directions, with holes in my shoes - primarily because that wasn't true.

And, notwithstanding some of the more petulant comments in the thread (e.g. 'The current lot of instructors and training agencies seem to be set in their ways, and are too lazy and/or unmotivated to learn to do anything different. '), I actively teach students to maintain buoyancy control using only their breathing to the extent possible (while wearing a BCD), I aggressively work with all of my students - OW, AOW, etc. - on proper weighting, and my BCD is a steel backplate and wing.

But, they all used to do it--I just have no reason to.

Well stated!

 

[stuartv]

Despite all the input from @REVAN about how diving without a BCD is so good I have still not had the answer as to how to dive sans BCD with a 7mm wetsuit to depths of 20-30m. Heck even at 10m it is probably about 3-4kg of buoyancy lost which is getting in the realms of being hard to control with breathing alone for an extended period.

I was talking to my dad last night. He's 71. He started diving when he was approximately 14, living in north FL. He was diving FL caves back when that was a brand new thing. He joined the Navy after high school (so, around 1964-ish) and took his scuba gear on the ship with him, which earned him the privilege of being assigned diving tasks. He was not a Navy Diver - just a seaman with scuba gear that got sent into the water to do stuff sometimes. The deepest he ever dived on an assigned task was 190 feet or a little more. I asked him once how he learned to dive that deep and he said "I got the Navy Diving manual and I read it."

All of his diving back then was done using double steel 72s and in a thick Farmer John style wetsuit. He never, ever had any type of BCD. Not even the old horse collar style. He said he wasn't even sure such a thing existed back when he was diving in the Navy.

So, diving to 190' in a thick wetsuit, with double steel tanks. And no BCD. The idea makes "old school" seem positively hipsterish.

I told him about the case study from the DAN report about the guy that died carrying 50# of weight. His immediate response was, "well that cleaned up the gene pool a bit."

I gave a little thought to how he could be successful in diving that way. My conclusions are:

- double 72s still isn't that much gas. Probably around 10 #s of gas. So, with proper weighting, he would still only start a dive 10# negative. What he said was that back then, divers developed a feel for how heavy they should be at the start of their dive. He would start heavy and end a little light. I took that to mean that at the end he would be positively buoyant, but so slightly positive that he could still stay down, just using breath control.

- the wetsuits back then were (I think) made out of neoprene that does not compress very much at all - totally unlike the stuff in most modern wetsuits. So, I suspect that even at 190' his wetsuit compression was not much. So, with that kind of wetsuit and full tanks, he might still only be 15 to maybe 20 #s negative at the very beginning of a dive (at a very deep depth). An amount that he could easily deal with by finning (my dad was a swimmer in high school that competed at Nationals, and played football and wrestled, so he was super fit back then).

None of that is intended to support the idea of training without BCDs. It is just intended to illustrate that it is possible to do just about any kind of recreational, single tank diving without a BCD - if you really want to.