If a diver needs more ballast than his weight-integrated BCD can safely accommodate, it is much safer to explore alternative methods of attaching ballast to the rig -- weightbelt, separate weight harness, weight pockets attached to tank cambands, etc.
Absolutely. And, unfortunately, that is not where many newer divers are in their development. They may have just spent a not inconsiderable amount of money on a bright, brand new, weight-integrated BCD (possibly, even in spite of a recommendation from an instructor, that a weight belt is the better starting point
), and discussing the need to buy a weight harness, or even weight pockets for the tank cam bands, in addition, is not what they want to hear.
I went down that road very early in my diving (and have a nice DUI Weight and Trim harness that has sat unused in a dive box in my garage for 8 years). When divers who have AL80s, and have just bought a drysuit, now ask whether they should consider a harness, I generally answer, 'NO'. The better solution is to work toward optimal weighting, and then possibly employ a simpler, and less expensive, gear approach (if needed) such as weight pockets on the cam bands.
bubbletrubble:
Over-stuffing weight pockets can sometimes complicate weight-release during an intentional ditching maneuver. Moreover, as you found, weight distribution can be suboptimal for surface swimming (or UW swimming).
I have made these comments in a number of other threads, as well. It is one reason that I have not generally been an advocate of weight-integrated BCDs, for newer divers in particular. While the possibility of interfering with weight release exists, dropping weights is fortunately an action that is seldom needed. A far more common result of overweighting is the comment that, 'a back-inflate BCD will push you face down in the water'. And, that is where excessive weight (because of i) a very buoyant exposure suit, and ii) the tendancy of many newer divers to overweight themselves), combined with a weight-intregrated BCD, creates a false impression. It is not (only) the position of the lift (behind the diver), per se, that creates the face-down attitude, it is as much the position (and amount) of the weight. On many weight-integrated BCDs, the weight pockets are slightly forward of the midline of the diver's torso, when viewed from the side in a vertical position. The lift is aft of / behind that midline. More weight in front, combined with more lift in back, and down the face goes. And, when a diver starts to go face down, the instinctive reaction is to add air to the BCD, making the problem worse. And, when is it particulaly noticeable to the diver? Frequently, it is at the end of their dive, when they have surfaced and are re-boarding the boat or heading to shore, when their (now near empty) AL80 has moved from being somewhat negatively buoyant, to being neutral, or slightly positive. More relative lift has now been added behind them, further enhancing the sensation.
bubbletrubble:
Here in San Diego, I have encountered a number of beginner divers who complained that their BCD weight pockets weren't big enough to accommodate the lead weight that they needed (with a rig coincidentally featuring an AL80 tank).
If it is any solace, it is not just San Diego. We see it in the east, where people are diving cold quarries.
bubbletrubble:
In all of these cases, with attention to proper weighting (weight check) and proper distribution of that weight (to promote horizontal trim), the divers were able to construct a properly balanced rig...even with an AL80.
Fully agree. It can be done with an AL80. If that is what a diver has to work with, great. And, I do not generally believe in technology / gear solutions to a technique problem. But, if a diver is buying a new/ first cylinder, and they know they will be using a buoyant exposure suit, I also believe it is better to get something that doesn't add to their ballast need, and which has a bit more air, anyway. An alternative argument could be, 'Learn to weight yourself properly for an AL80 and everything else will be easier.' I often tell students that. But, I also tell them that, by and large, going with a slightly larger, steel cylinder, when they finally buy a cylinder, is a wise purchase. If nothing else, resale value is higher.
bubbletrubble:
Very few students exiting basic OW class know how to calculate whether a BCD has "enough" lift. This is probably due to the fact that the vast majority of recreational BCDs on the market provide excessive lift.
Fully agree. Lift calculation is not something that is usually covered in the OW curriculum (unless the instructor adds it to the discussion). Frankly, at the OW level, it is just one more concept, and piece of information, to get lost (and subsequently forgotten) in the the sea of factoids. (If I have to choose between gas management and lift calculation because of time limitations, I know what I am going to choose to cover.) I do, however, raise it in AOW (and even direct AOW students to ScubaBoard and tell them to search for threads where Tobin offers estimates of lift calculation).
There was recent thread in one of the Equipment forums involving a diver who wanted to purchase a Ranger as a first BCD. I recommended against doing so. I am a very big fan of Zeagle products (good quality and excellent after-sale support), the Ranger is a marvelous BCD, my first BCD was a Ranger, and it is one of the more comfortable BCDs I have ever worn. But, at 44 lbs of lift, is is conspicuously over-sized for single cylinder diving. The Stiletto, which the OP in this thread recently purchased, is somewhat less over-sized (at 38 lbs). But, you are 'spot on' - many BCDs are simply oversized for the needs of single cylinders.
