BC's ability to float gear at surface

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divewench

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As part of a rescue diver course I had my equipment removed in the water as I played victim. I was very surprised and dismayed to find that my bc sank like a rock to the bottom the instant it was removed. I discovered that I didn't have the bc quite full of air, and by filling it completely it would float just below the surface. But it was also holding 8 less pounds than I normally dive with (left the nonditchable weight on shore) and the tank was not full (it was about 85%) I am confident that if I had all the weight on it and a full tank there would be no way it could stay afloat. I have removed my bc before, but only in a pool, where I neither needed, nor used much weight.

My bc, a ScubaPro LadyHawke is adverstised as being able to hold 20 lbs of ditchable weights and an extra 10 lbs that cannot be ditched. Its buoyancy is stated as 36 lbs. For salt water diving I use 28 pounds of integrated weight and a HP steel 80 tank (buoyance full about -11 lbs, I think). I assumed that if I used my equipment within its specified design limits that everything would work as it should. Unfortuntely I didn't do much thinking beyond that, if I had given an ounce of effort to running the numbers (30+11 > 36 ), I hope I would of noticed a problem. Given ScubaPro is selling the bc with the ability to hold 30lbs, shouldn't they only do so if that bc has enough lift to support the 30 lbs of integraged weight PLUS a tank (even if I was diving Al, I think I would be awfully close to the limit). For that matter, why would the LDS that sold me the BC, the tank, and the 30 pounds of weight want to sell me something that would sink to the bottom if I (and all the buoyance my undergarment and dry suit provide) am not in it. In reading the recent posts regarding buoyancy requiments of a bc, it sounds obvious to me that a bc should float your gear, so obvious that I never thought that it would be something I would have to worry about unless I was building my own rig (like a bp/wing setup).

I figure I was either very naive to assume that ScubaPro and/or the LDS would want my rig to float on the surface and too dumb/lazy to do the math myself, or I am now missing something obvious and am perhaps using the equipment in a manner they didn't expect, or maybe my expectation that my bc float on its own while fully loaded is unreasonable?

I think I should get a larger bc. However, I would like to not feel I have to rush into a purchase. How high a priority should I place on replacing this rig? Is it reasonable to continue diving with it understanding its limitations for 3 to 6 months(diving about once a week) while I try to figure out what I want and how to pay for it. Given the numbers it looks to me like I need at least 45 lbs of lift, does that sound right?
 
This happens alot with weight integrated BC's. Dont get a larger lift BC just because it doesnt float everything at the surface. You might try moving some of the lead to a weightbelt, if you are going to be doffing your kit in the water alot. If you get out of the water with your kit ON, then dont worry so much about it. Because when you get into the BC, your natural buoyancy will help you stay on the surface. Now, if you are having trouble staying on the surface with you in the bc, then I would think about changing the BC.
 
Hmmm... In the same exercise in the ocean in a wetsuit, I found that when I pulled off my BC, it floated but I sank.

I think I'd want to get in the pool with that BC and start playing with the weights to see how much lift is there. Are you perhaps more bouyant than average?
 
28 lbs plus an -11 lb tank is a lot of weight. I am assuming you are fairly experienced if taking the rescue course, but that is a lot of weight even with a 7mm wet suit or drysuit, so I at least have to ask if you are perhaps overweigthed.

My spouse dove a BC for a while with 28 lbs of lift an it floated fine on the surface all by itself as long as she wore the weights on a belt, but it did not float her very far out of the water. She is much more comfortable in a BC with 45 lbs of lift, at least in cold water with the greater weigth requirements that go with the thicker exposure protection.

I would regard any BC with less than 45 lbs of lift as being a tropical BC that is not well suited to cold water use. However that is strictly a personal opinion based on 2 decades of experience that none the less gets flamed frequently.

Last season I recovered 2 BC's that promptly sank when removed in the water. Both were in 40 ft of water with no current so it was not a big deal as long as somebody still had air left. More alarming however was a diver who found she could not get off the bottom at 100' due to being over weighted and in a BC with relatively little lift capacity. It's one of those places where a little extra lift in my wing came in handy.

In all three cases a substantial portion of the bouyancy came from the suit. That worked ok in the first 2 cases in shallow water but was very problematic in the third case deepwater where the suit compressed to a point that the remaining bouyancy of the suit and the capacity of the fully inflated BC was so inadequate as to prevent a slightly tired diver from swimming up on her own. Dropping weight is normally an option but one that can also go to far and lead to an out of control ascent. A 100' down is not exactly the ideal place to be when readjusting one's weight requirements.
 
This is not a flame, just merely a question:
Are there good single tank wings out there that are designed for single tanks in cold water?? The biggest i have seen so far (very limited experience) for single tank use has been a 36#. Above that size all i have seen are the hybrid single/double tank wings at 40+#.

We are thinking of going up to the colder north for a few years and although we are getting systems with around 30# lift donuts for our BP's down here, i wasnt sure whether or not these or the larger 36# could still be used with the extra weight required for a drysuit.
 
Oxycheq has their Single Tank #44 lift wings in the original style and the new Signature Series wings. I just got my Sig. series wing (#44) but haven't had the chance to put it in the water yet. Here is where I purchased mine.

http://www.covci.com


simbrooks:
This is not a flame, just merely a question:
Are there good single tank wings out there that are designed for single tanks in cold water?? The biggest i have seen so far (very limited experience) for single tank use has been a 36#. Above that size all i have seen are the hybrid single/double tank wings at 40+#.

We are thinking of going up to the colder north for a few years and although we are getting systems with around 30# lift donuts for our BP's down here, i wasnt sure whether or not these or the larger 36# could still be used with the extra weight required for a drysuit.
 
Well I'm a big guy diving cold water. 6'-3" 240lbs. I wear 36lbs of weight integrated in my zeagle tech. The 65lbs bladder is great. Never an issue lifting and my rescue course was simple getting people off the bottom. Didn't even need to use their BC.

I removed my gear with a full tank, all weights, dive lights..... No problems.
 
simbrooks:
This is not a flame, just merely a question:
Are there good single tank wings out there that are designed for single tanks in cold water?? The biggest i have seen so far (very limited experience) for single tank use has been a 36#. Above that size all i have seen are the hybrid single/double tank wings at 40+#.

We are thinking of going up to the colder north for a few years and although we are getting systems with around 30# lift donuts for our BP's down here, i wasnt sure whether or not these or the larger 36# could still be used with the extra weight required for a drysuit.

The Halcyon Pioneer 36 is more than enough for cold water diving. I have an 8 pound channel weight and a 6 pound backplate, and it still floats very high in the water.
 
I have a SeaQuest Pro QD and I dive ocean with 6 ditchable lbs...and 4 lbs trim non ditchable. Plus there is a 13cu ft pony bottle attached.

When inflated it will life up out of the water no problem the gear with out me in it and lift me up when i am in it.

I will let you know what my new bp and wing does when it arrives and I can get to the pool to play with it.
 
Egads....that last post is just glaring proof you should never try to type a decent post while holding a conversation both on the phone and someone standing at your office door the same time.

Bottom line....the SQ P QD will lift all my gear up out of the water when I am not wearing it...and....it will lift me well up out of the water when I am wearing it with all the junk I dive with.
Articulate...articulate....articulate.....finger position on the keyboard is critical
 
https://www.shearwater.com/products/perdix-ai/

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