View Full Version : Using BCD for Buoyancy instead of Dry Suit
bluemooner2001
14-12-2009, 13:54
Hi All
I recently bought an 0'Three Drysuit previous to this weekend I had done about 6 dives in it but always seemed to have issues with my buoyancy and in particular floaty feet which stopped me enjoying the dives as much as normal.
Anyway this weekend I went to Capenwray and tried using my BCD instead, with just enough air in my suit to stop the suit squeeze and hey bingo it worked a treat and I felt more relaxed than I ever have in a Dry suit.
So I was wondering if anyone else has turned to using their BCD instead of their suit as this now seems the way forward for me.
Bob
ChristianG
14-12-2009, 14:16
Anyway this weekend I went to Capenwray and tried using my BCD instead, with just enough air in my suit to stop the suit squeeze and hey bingo it worked a treat and I felt more relaxed than I ever have in a Dry suit.
So I was wondering if anyone else has turned to using their BCD instead of their suit as this now seems the way forward for me.
Actually Bob, that is likely to be the way forward for most people. :D
After all, that's why a BCD is called a Buoyancy Control Device.
bluemooner2001
14-12-2009, 14:22
:) of course.. no but in all seriousness, the Dry Suit course instructs you to use your suit and to forget about your BCD expect on the surface. So not knowing any better I used my suit, but then tried the BCD route for the first time to see how I would cope.
I guess unless someone tells different then you know no better, especially if your a new diver.
Nigel Hewitt
14-12-2009, 15:13
So I was wondering if anyone else has turned to using their BCD instead of their suit as this now seems the way forward for me.Rolls on the floor laughing... :D
I set the auto dump to wide open and add air to keep the suit comfortable but otherwise ignore it. My suit is there to keep me warm and dry which it does excellently.
I have a buoyancy control device to control my buoyancy which does it rather well too.
You can fudge using just the suit by putting too much air in it but as you discovered it rather goes where it wants. You start the dive with over 3 kilos of air in the tank and you don't expect to bring it all back. The needed 3 kilos worth of buoyancy to balance that change in weight is 3 litres of air and that's over 5 pints. Look at the milk in the fridge and imagine stowing 5 pints worth of those containers in your suit. Remember this is extra - over and above what it takes to keep the suit comfortable.
Controlling your buoyancy on your suit is a good skill to have in your mental tool box. It means that the day your BCD inflator comes off the end of the hose you think "D*mn what's that going to cost to fix?" and punch a bit more air into the suit rather than "Argh! I'm going to die!" You just don't want to do it every time.
Luckily I didn't go on a drysuit course , just went diving with mates who had already sussed the minimum gas in your suit diving.:D
bluemooner2001
14-12-2009, 15:47
As I said, on the Padi Dry Suit Course you are told to forget about your BCD and use your suit, but for me my buoyany was a liitle unpredictable at times, so putting enough air in to keep me warm and comfortable and then using my BCD (for its intended purpose) for controling my buoyancy. I guess its down to personal preference at the end of the day, as you say its always good to know if your BCD blows at least your safe in the knowledge that you can use your dry suit.
John Bantin
14-12-2009, 16:41
I use minimum gas in my drysuit and no gas in my BC because I get my weight right. Some of you should try it.
Tony Dwyer
14-12-2009, 16:53
I use minimum gas in my drysuit and no gas in my BC because I get my weight right. Some of you should try it.
I'm with you on this John.
However, a fair number of people here aabouts strap loads of kit to themselves that significantly adds to their weight. Resulting in their having to shove mucho air in their BC to compensate.
I know one guy (slim and muscular) who is almost negatively bouyant in an empty (membrane) suit without a weightbelt. add a full 12 ltr twinset, two staging bottles, an umbilical torch thingy and various other bits and bobs and he is a brick. He has to use his wing for buoyancy, if he used his drysuit, he wouldn't be able to move! :)
Personally I think he's out to lunch. I prefer minimalist diving.
Enough air
comfy suit
warm water
Practically no air in the suit and not much in the BC, except on the surface.
John Bantin
14-12-2009, 17:08
I'm with you on this John.
However, a fair number of people here aabouts strap loads of kit to themselves that significantly adds to their weight. Resulting in their having to shove mucho air in their BC to compensate.
I know one guy (slim and muscular) who is almost negatively bouyant in an empty (membrane) suit without a weightbelt. add a full 12 ltr twinset, two staging bottles, an umbilical torch thingy and various other bits and bobs and he is a brick. He has to use his wing for buoyancy, if he used his drysuit, he wouldn't be able to move! :)
Personally I think he's out to lunch. I prefer minimalist diving.
Enough air
comfy suit
warm water
Practically no air in the suit and not much in the BC, except on the surface.
If your kit is heavier than water you should use some incompressible buoyancy to make it neutral or you might head the way of the chap who jumped in without his set turned on. (That's forever downwards.)
Richard Whitcombe
14-12-2009, 17:09
A *properly weighted* single tank diver can use the suit for buoyancy without worrying about too much gas volume - its only 3-4kg max.
Other than that i use my wing and have found most people more comfortable using that method. More fine control, more dumps, no gas migration issues, less floaty feet and so on.
ChristianG
14-12-2009, 17:16
Luckily I didn't go on a drysuit course , just went diving with mates who had already sussed the minimum gas in your suit diving.:D
Yes, but ...
Ever fearful of starting yet another BSAC/PADI thingie, hopefully not, I nevertheless do fail to see why PADI apparently go what I would call the "wrong" route.
Terry, others that teach both, is this really PADI's preferred modus operandi? I don't know, I'm simply asking the question.
I nevertheless do fail to see why PADI apparently go what I would call the "wrong" route.
Because it isn't the "wrong" route.
Given a *properly weighted* diver, there is only a couple of kilos difference between the beginning and the end of a dive for a standard, single-tank setup as would be used by people just starting to use a drysuit. That means that a diver using the suit for buoyancy is only going to have a couple of litres extra gas in the suit over minimal squeeze - that's a small amount of gas.
The problem comes when the diver is not properly weighted. The more over-weighted someone is, the more excess gas must be carried in the buoyancy cell - and if that's the suit, it really does cause problems. This is one of the reasons I like people to try using the suit for buoyancy - it highlights overweighting problems that are largely masked by 100lb-lift wings.
Once a diver has progressed to taking in more gas (muiltiple cylinders), then the above argument no longer applies - but for those starting out, it keeps the complexity of the dive low (the diver is only managing one buoyancy cell), helps sort out eight issues, and is no real difficulty either.
Vic.
Because it isn't the "wrong" route.
Given a *properly weighted* diver, there is only a couple of kilos difference between the beginning and the end of a dive for a standard, single-tank setup as would be used by people just starting to use a drysuit. That means that a diver using the suit for buoyancy is only going to have a couple of litres extra gas in the suit over minimal squeeze - that's a small amount of gas.
The problem comes when the diver is not properly weighted. The more over-weighted someone is, the more excess gas must be carried in the buoyancy cell - and if that's the suit, it really does cause problems. This is one of the reasons I like people to try using the suit for buoyancy - it highlights overweighting problems that are largely masked by 100lb-lift wings.
Once a diver has progressed to taking in more gas (muiltiple cylinders), then the above argument no longer applies - but for those starting out, it keeps the complexity of the dive low (the diver is only managing one buoyancy cell), helps sort out eight issues, and is no real difficulty either.
Vic.
Christian
Following Vics good post (see above).
In fairness to PADI, the BSAC teach the same, bouyancy by preferrence is done on the suit.
As a couple of people have said for a single cylinder, correctly weighted diver, it should be a non issue. It really only becomes an issue when a diver starts to carry a lot of cylinders, whose weight change as the gas is used.
Gareth
Nigel Hewitt
14-12-2009, 18:50
As a couple of people have said for a single cylinder, correctly weighted diver, it should be a non issue. It really only becomes an issue when a diver starts to carry a lot of cylinders, whose weight change as the gas is used.
But when I just carry three two litre cylinders people whinge about bailout and looking after my buddy. Then I dump the buddy and they whinge even more.
There's no pleasing some people...
But when I just carry three two litre cylinders people whinge about bailout and looking after my buddy.
Well, there's your problem, see.
You should carry two 3-litre cylinders instead. 2L? Pah!
Vic.
p.s. :-)
Nigel Hewitt
14-12-2009, 19:11
Well, there's your problem, see.
You should carry two 3-litre cylinders instead. 2L? Pah!
Used to...
...but helium in the suit inflate makes me cold and using the O2 could be a bit dicey after a the traditional Saturday night dive weekend curry.
...but helium in the suit inflate makes me cold and using the O2 could be a bit dicey after a the traditional Saturday night dive weekend curry.
Surely that is a perfect balance? feeling a chilly from the He - add some O2 to your suit and light up the methane, instant suit warmer :)
Richard Whitcombe
14-12-2009, 20:19
Yes, but ...
Ever fearful of starting yet another BSAC/PADI thingie, hopefully not, I nevertheless do fail to see why PADI apparently go what I would call the "wrong" route.
PADI allow you to teach either and mention that both are options. They recommend the suit only for reasons above but its not mandatory. The same IIRC as BSACs course.
PADI do allow hog looping and primary donate though.... /me runs for cover :)
A *properly weighted* single tank diver can use the suit for buoyancy without worrying about too much gas volume - its only 3-4kg max.
On Sunday I assisted an experienced diver remove 3 kg when doing the Buoyancy Workshop.
The extra weight made me bounce up/down like a trainee.
Edward
Bob Butcher
15-12-2009, 10:11
The original post was started by "foaty feet".
Rule one, get your weight right.
Rule two ,get it in the right place.
Moving the cylinder up or down the BC will move your centre of gravity,curing floaty or lead feet at a stroke. Also moving small weights to "trim straps or pockets" can make an amazing difference.
An assent is easier to control for the less experienced diver if air is expanding in one piece of kit only , so the BCD/ Wing is for surface use only, untill your kit weight ie. twins, side slings, torch,reels etc.become too heavyfor your neck seal to hold. But by then you are experienced enough to cope with the extra task of dumping air on assent from multi pieces of kit.
As with all diving, no one way is right, experience will prove the safest way for your type of diving.
An overweighted diver is, rather conversely, a main cause of rapid ascents. You compensate for the lead with gas in your suit which on ascent, especially in the last 10m or so, can't escape rapidly enough.
Don't forget that the large volume of air in your suit will double from 10m to the surface so that's a hell of a lot of gas you need to vent through your suit dump. As long as you are aware of this then it's not a problem. The issues come when a drysuited diver does not vent often enough in the last bit. You need to be conciously venting every 1/2 metre or so.
Floaty feet? Jet fins.
John Bantin
15-12-2009, 11:43
Actually Bob, that is likely to be the way forward for most people. :D
After all, that's why a BCD is called a Buoyancy Control Device.
..and that is why a car has a Starting Handle.
Tony Dwyer
15-12-2009, 12:04
Actually Bob, that is likely to be the way forward for most people. :D
After all, that's why a BCD is called a Buoyancy Control Device.
Grr!
BCD = consarned Merkin TLA (three letter acronym)
BC (Buoyancy Compensator) was always good enough for me, when it wasn't being a STAB, Horsecollar or ABLJ that is.
Richard Whitcombe
15-12-2009, 16:29
Floaty feet - get a drysuit that fits. Not too long in the leg, not much airspace in the boots. Get your weighting correct.
THEN on a single you can use suit only. Even though i think the wing is still far superior and comfortable.
Most people i see complaning about floaty feet in a drysuit are overweighted and trying to do the buoyancy with the suit at the same time.
Most people i see complaning about floaty feet in a drysuit are overweighted and trying to do the buoyancy with the suit at the same time.
That's *almost* always the case.
But I've also seen people *so* used to being overweighted that, the first time they actually achieve a neutrally-buoyant, horizontal position, they *believe* they're about to have a feet-first runaway - because the experience is so different from what they've become used to.
Sometimes, complaints of "floaty feet" aren't actually a bad thing.
Vic.
Richard Whitcombe
15-12-2009, 16:48
Annoyingly i suffer from sinky feet. Im actually countering it currently by a bit more air in suit.
Nigel Hewitt
15-12-2009, 18:12
Sometimes, complaints of "floaty feet" aren't actually a bad thing.I think you're right. My nice weight set that puts me dead level, no effort on a stop feels a bit foot-light when I've just crashed down a shot and I'm trimming out as I move onto the wreck but it soon passes. I think as a bipedal creature we think head up is normal and it takes a while to adjust to being a bird again (divers don't swim - they fly).
Annoyingly i suffer from sinky feet. Im actually countering it currently by a bit more air in suit.
I'll go with that.
I do agree with Vic, in that when people do achieve the correct trim they worry that their feet feel floaty, people need to be 'conditioned' to thinking its normal.
When I started with a drysuit, (many many years ago,) ankel weights seemed to be standard, after a while I stopped using them. Final I got rid of the big lumps of rubber that where my fins for, at the time, the sexy plana avanti's. I got the weight right down when I switched to Force fins. Now I've got lovely 'floaty feet'.
Part of the issue is people are conditioned to worry about inversion & feet first ascents, with that, & excessive weight, its very difficult to get people to feel comfortable horizontal when you finally do get the weighting right.
One of the great things about rock boots (& the variants) is the issue of air in the migrating into the feet is greatly reduced.
Gareth
In 'normal' diving as has already been said, there's little difference at the beginning & end of a dive. I was taught to carry a weight belt that gave me a couple of pounds buoyancy with an 'empty' cylinder at the end of a dive.
Use the BC/horse collar or whatever for extra surface buoyancy at the end of the dive. The other thing to think of, is that if there is a problem and both divers have been using both suit and BC for buoyancy, then the diver performing a controlled lift would have to monitor and possibly vent four buoyancy devices.
Richard Whitcombe
16-12-2009, 13:34
, then the diver performing a controlled lift would have to monitor and possibly vent four buoyancy devices.
In reality its easy. If its a shoulder dump keep it fully open. Even a cuff dump you can fully empty one air source control with the next, after thats empty start emptying from the other and so on. In practice this isnt a problem.
Nigel Hewitt
16-12-2009, 13:44
The other thing to think of, is that if there is a problem and both divers have been using both suit and BC for buoyancy, then the diver performing a controlled lift would have to monitor and possibly vent four buoyancy devices.
But if you are about to lift somebody you have to manage their suit and yours and I would expect to lift them on the their BCD/Wing. The only BCD/Wing I can discount is mine because I'd empty it before we started up to try and ensure they are lifting me so if anything goes wrong and they get out of my grip they are headed up.
But there again it it was me there are rebreather counterlungs to manage too so you can't win.
I use the wing to trim out and just keep the suit comfortable. I find the wing is easier to fine tune on because, as a RB diver, I don't have the luxury of 'breathe to trim'.
northern_diver
16-12-2009, 17:15
Sadly, my copy of the SAFE DIVING book is at home, but if memory serves from reading and someone talking to me that normally know there stuff, dont BSAC recomend that-
The BCD OR SUIT is used,as long as its used in a consistant manner, e.g not mixing a matching.
So you either dive using the suit for all, with the BCD/wing as a backup
or
Dive with the BCD and the suit for taking suit pressure off and as a backup.
Personally, i have my suit valve fully open and use my suit as a back up bouyancy system with minimum air in for suit nip with the BCD been used for assisting boyancy.
Rational-suit is to keep warm and not wet, air/gas easy to put in if needs be by the nice and handy chest inflator.
The BCD/Wing has significantly more ways of dumping air/gas (4) than my suit (2), so im the event of a issue, i have more ways to dump air, especially as 1 of the suit methods involves pulling the neck seal as a emergency dump
I can dump more sensitive amount of air/gas, via the Over pressure valves on my BCD/wing than with the manual override on my suit...which hardly ever works at depth as it's not got much air in to allow out (Boyle's law)
I feel more....capable and neat, with a more stream lined or slightly tight suit, whan in effectively a air/gas filled bag....very odd personal preference.
Any buddy's im with are either experience enough to know to open/manage my auto/shoulder dump or if not, i tell them and have it open anyway, and they dont have to lift my arm to dump as in a cuff dump, just put my arm on there shoulder and it dumps happily.
MY rational, working for ME with some of the points, off the top of MY head (as im supposed to be writing my essay on clandestine graves;) ) on MY methods. So i would suggest playing with different methods and seeing what works for you. Your buddy should be made aware of your choice i feel however.
John
OR ditch the faff and just dive in a wetsuit.
comon give the dark side a trial. its realy fun and we have kittens.
that said when i was diving in the evil, constricting, uncomfortabel and general pants suit i only used my BCD for boyancy and never my suit on a shallow dive occasionaly i didnt even connect my hose
northern_diver
16-12-2009, 18:44
OR ditch the faff and just dive in a wetsuit.
comon give the dark side a trial. its realy fun and we have kittens.
that said when i was diving in the evil, constricting, uncomfortabel and general pants suit i only used my BCD for boyancy and never my suit on a shallow dive occasionaly i didnt even connect my hose
Im allergic...
But my regular home buddy does keep saying some stuff about diving wet in summer,i was just assuming thathe wanted me to stab his suit a couple of times before it gets packed it away;) :p
Might try it, i do actually, somewhere have some sort of wetsuit (semi i think) so i suppose i could do something along those lines...just to remind myself of what the trainee's go through:eek: :)
Floaty feet aint a bad thing, as it helps keep the feet up out the dirt a little more, so everyone can do nice fin techniques that dont kick up the silt etc get used to it and get on with it, its ok.
John
Nigel Hewitt
16-12-2009, 18:45
OR ditch the faff and just dive in a wetsuit.
comon give the dark side a trial. its realy fun and we have kittens.
that said when i was diving in the evil, constricting, uncomfortabel and general pants suit i only used my BCD for boyancy and never my suit on a shallow dive occasionaly i didnt even connect my hose
ROTFL
If I'm diving wet I'm freediving.
What is this buoyancy you speak of?
that said when i was diving in the evil, constricting, uncomfortabel and general pants suit i only used my BCD for boyancy and never my suit on a shallow dive occasionaly i didnt even connect my hoseHmmm. So you don't think the lack of air in the suit might have had something to do with it being constricting and uncomfortable then :)
John Bantin
16-12-2009, 19:39
How many of the experts advising here have been banned from diving on a Red Sea liveaboard because the dive-guides thought their buoyancy control was so scarily bad? Just thought I'd ask!
na the constriction comes from the suit and its lack of mobility. underwater its slightly better but i couldent realy move my arms n legs propery
i do admit to tossing the concept of a 3mm shorty over my 2mm long suit for the comming months around but i cant find anywhere thats elling them in FB sizes.
what is this dry of which you speak when diving? seems wrong to be doing a watersport and not wet
Richard Whitcombe
17-12-2009, 15:58
I go diving to see stuff underwater not to get cold and wet. If i could stay completely dry and warm id love it.
If i just enjoyed being cold, wet and miserable there are far cheaper ways of doing it than going diving!
I go diving to see stuff underwater not to get cold and wet. If i could stay completely dry and warm id love it.
Royal Navy submarine service is recruiting.......:D
Richard Whitcombe
17-12-2009, 17:02
Royal Navy submarine service is recruiting.......:D
Lacks windows to see out of
welll ill be diving at the weekend in a 2mm wetsuit.
northern_diver
17-12-2009, 19:27
welll ill be diving at the weekend in a 2mm wetsuit.
You have a card for that right?;)
John
what you mean i have to do it in shorts n tshirt cause i dont have a protective clothings SDC ticket done?
ohhh thats going to be chilly nadgers time
northern_diver
17-12-2009, 20:03
haha, think i'd be chilly in a 2mm anyway....diving somewhere warm by chance?
John
Richard Whitcombe
17-12-2009, 20:09
Water is down to 23c here so its drysuit for me without doubt. Tried a 3mm hooded vest under a 7mm semi dry with 5mm shortie on top of that but froze.
Sadly drysuit is flooding totally now due to being unable to get proper glue to change seals. Its STILL warmer than a wetsuit though!
haha, think i'd be chilly in a 2mm anyway....diving somewhere warm by chance?
John
yeah torbay.
probably the sunker (ore stone).
toasty warm. ive even gone whole hog an put the FFM on to cover the few bits that just arnt neoprened
i was doing hour an a half dives comfortable in 16 degrees.
northern_diver
18-12-2009, 21:54
yeah torbay.
probably the sunker (ore stone).
toasty warm. ive even gone whole hog an put the FFM on to cover the few bits that just arnt neoprened
i was doing hour an a half dives comfortable in 16 degrees.
Nice, sadly, i think the NorthSea is a bit colder than that at the moment (or when i'd be up there anyway) so it'll be a drysuit for me....Might even get the FFM out for a bit of a play:)
I might well try a wet in summer though i've heard rumours of overseas diving over newyear, so i might be in a wet then.
John
well 2 weeks ago it was down to 10 degrees, im guessing it will have droped to 8 ish. with a surface temp of 0-3 degrees less wind chill. so i am packing my big russian winter jacket.
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