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Ginger, Irish, sometimes stroppy
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Hi all

I am thinking about booking myself some Dry suit training as a first step towards UK diving and have a question for you.

How much BCD lift do you need while dry suit diving ?

I am assuming it equates to slightly over the amount of lead you are carrying, if this is so how could I guestimate how much lead I would need with a drysuit ? (currently I need 8kg of lead to get me down in the Red Sea with a 5mm Semidry).

The reason for this question is that I would like to know if my baby warmwater wing will be enough.

Thanks in advance

Conor

BTW If anyone else out there is in a similar situation and would like to join me then let me know
 

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Not as tall in real life
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<font color='#000080'>Simplistically yes.

You will need enough lift to offset your negative bouyancy.

Typically you will be more negative at the start of the dive than at the end when you only have 50 bar left.

What is the wing, just out of interest ?.

I have used a trekwing when diving with a single 12l and pony.  Using upto 8kg of lead and that is 3kg more than I needed.

The conditions you dive in may also have a bearing on this,  just enough lift may only just keep your head out of the water.  Not pleasant in a rough sea.  

Daz
 

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<font color='#0000FF'>I'm sure it'll be more than enough. My other half dives with my old Dutton BCD, using a membrane DS,  I doubt the BCD has much more lift than my dSMB, but as long as you're correctly weighted you don't need massive amounts of lift.
I used this BCD with single 10s 12s or 15+Pony for a good few years, nil problemo  

Chee-az
Steve
 

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I once tried to write a guide that'd let you work out just how much lift you needed.

It never got past the draft stage, but you might find it worth a read:

Previous post
 

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Ginger, Irish, sometimes stroppy
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Thanks for the replies.

The wing is a Dive Rite Travel wing (14kg of lift), which gives plenty of lift for my warm water frolics. My concern is that if I use a dry suit, and it fails I will need to get all the lift to get the lead up from the wing.

I guess the main problem is I have no idea how much lead I will need with a dry suit. If I need 8kg with a 5mm Semi and Al 12L, can this give me an indication for initial dry suit weighting ? The odd bit is when I wear a 5mm shorty and hood with the same semi I need 14kg, but this is obviously due to 10mm of neoprene and a lot of trapped air. Then again I have no idea of the type or fitting of the dry suit I would be using which I am guessing will have a huge impact on the weight required.

I considered buying one of the bigger wings at the time, but was hoping to get a dedicated singles wing and then upgrade if and when I move to doubles.

Any help would be appreciated .

Cheers

Conor

BTW I thought I would recieve mails from YD when people reply, but I haven't as yet. I have checked the settings and all seems in order, could anyone give me a pointer ?
 

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You could always take an SMB or two with you to give you some backup lift if necessary...

I use a membrane drysuite & Weezle extreme, with twin 7s I use.. umm... 9kg of lead, plus steel backplate, so around 11kg in total.

So 14kg would be marginal for me, but just about enough even in the event of a full suit flood. Which just isn't a big worry for me..

On the other hand, my weight is bolted to my aqualung, so I wouldn't be happy using a 14kg wing, as it'd probably sink when I was de-kitting..
 

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Ginger, Irish, sometimes stroppy
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I would only be using the wing for singles (and no integrated weights) and so floating the rig shouldn't be a problem. Floating me on the other hand.....

Out of curiousity, could you give me an idea of your weighting with a single and wetsuit versus a single with dry ?

Cheers

Conor
 

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Sorry, no - haven't dived a single & wetsuit since the summer of 2000. And haven't dived a single & drysuit since.. umm.. winter 2000, come to think of it.

But I daresay somebody'll be around that can give you some idea...
 

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Hmmm.... I don't think it is advisable to try to gauge one persons lead requirements from that used by another diver, unless you know you are both the same weight, height, have the same amount of bodyfat and wear exactly the same drysuit undersuit and layers, all of which affect the potential amount of weighting required.
But just for info purposes: single Ali 200bar 12l with 5mm shortie wetsuit, 6lbs lead, single with membrane drysuit, Bodyglove thinsulate undersuit and 12l 232bar steel tank, about 24lbs lead.
HTH
Steve
 

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Hi all.

One thing I thought was that if you only have just enough lift to remain positive when full, then I wouldnt want to be the poor sod lifting you in an incident and having to control four bouyancy devices and keep your reg in your mouth.

I want enough bouyancy to lift us both to 6m/surface in your kit alone. I can dump my own bouyancy and just control yours to get you up and out without doing a Polaris missile impression.
You dont have to go over the top but as you pointed out, 14kg lift is probably a bit feeble to get two drysuit weighted divers to the surface safely.

Stu.
 

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I'm not so sure about that - bear in mind that correctly-weighted divers will only be as negative as the air in their cylinders. With a 15L single, that means about 4kg. So 14kg is more than enough to get you both to the surface, as you only need a maximum of 8kg.
Not much good for twins, true, but this is a singles-only diver, so that's irrelevant.
The only time 14kg becomes too little is with drastically over-weighted rescuer involved or when a CBL is being done with a flooded drysuit.
There's not much you can do about how much lift your buddy might need, and in the event of a flooded drysuit, well, I suspect that'd be the time for you empty his wing completely, and do the lift on your own buoyancy. Not ideal, but the chances of doing a CBL on someone who's lost his drysuit buoyancy are too small for me to loose sleep over...
 

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Glad you added that Dom, cos I was starting to lose the plot on this one as I believed that a correctly weight diver was just able to see above the surface when breathing deeply in with 50bar left in the tank, so all this talk of having to lift the weight on my belt was starting to get to me.

Do we all agree with Dom's comments here?

Matt
 

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aka Rich.
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Camdiver, I'm doing the PADI Dry Suit speciality this weekend for similar reasons - see what diving in the UK is like.

As part of the course I've got to do the knowledge review and that's from the PADI Adventures in Diving course. Within the chapter is a calculation for working out approximately how much weight you'll need based on body weight, kit, dry suit type and salt/fresh water.

I'd worked mine out at around 9 Kg, based on salt water, steel 12 ltr, 67Kg body weight and a membrane suit. It seemed to work out just slightly more than using a 7mm full wetsuit with similar kit. However, this might just have been for my body weight.

I would imagine the dive shop running the course would be able to tell you as they'll come across the questions all the time.

Also, I've noticed that most shops will most likely lend you all the gear anyway, unless you particularly wanted to use your BC. Some places do a pool dive for you to try kit out before going OW, so that could be another option for you.
 

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As already pointed out, it's individual, but the following info' may be of some help. I use a 10 L x 300 bar cylinder and 3 L x 300 bar pony, total weight of the two cylinders filled 25.3 kg, and a membrane drysuit. With the Transpac II and Recwing, I need 9 kilos of lead altogether, 7 kg on my weight harness and 2 x 1 kg ankle weights*. You might want to consider buying a Recwing for your TP II. The Travelwing is a bit minimalistic for drysuit diving in my opinion.
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*Before anyone tells me off for wearing "legirons", I've started wearing ankle weights again due to floaty feet caused by much too big boots – the suit was made to measure for someone else.
 

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No, I dont agree with dom.

If this guy has never dove dry before, whats the chance that he will be correctly weighted from the off?

Pretty small IMHO.
Stu
 

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Ginger, Irish, sometimes stroppy
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Thanks for all the replies.

I wasn't suggestiing that I listen to other peoples weighting and jump in with a dry suit unsupervised. Instead I was just curious what ballpark of weighting I would be likely to be in. I expect my first few dry-dives to be heavy compared to what my weighing becomes as I get used to it for various reasons, nerves, new equipment etc. I would be willing to bet that I will lose a kilo or two (or more) in the course of my first few dry dives. I like diving my BCD and would rather use as much familiar equipment as possible so I can focus on getting used to the dry suit.

The following is me thinking out loud so feel free to correct me, in fact please do.

My undertsanding if weighting is that the bulk of the weight is required to compensate for the buoyancy of the exposure protection, but with compression of neoprene suits more air needs to be added somewhere (suit or BCD) to compensate. WIth dry suits (especially membrane and compressed neoprene) most of the bouyancy loss at depth comes from the compression of the air in the suit, which can be compensated for by adding air to the suit.

So if I need 7kg of lead to sink a membrane suit, if it floods, assuming 7kg of the around 10kg of lead on my belt was compensating for the air in the suit I would need 7kg of available lift to be neutral after the flood (plus whatever else I required to be neutrally bouyant before the flood, such as due to overweighting, air used etc.). The other 3 kg of lead would be to compensate for the air used in the dive and bouyancy of other equipment etc. This would suggest that I would need between 7(at the end of a dive) and 10 kg (at the start of a dive) of lift available in my BCD to be sure. My wing has 14kg according to Dive Rite, I would say it probably has 12kg in use and so would be sufficient for the scenario above.

If I was found unconcious at the bottom by another drysuited diver, then he would have to choose which of the four available sources of bouyancy control he would rather use. Generally I believe people have a preference for the casualties lift and the rescuer would probably discover a drysuit flood quite quickly so may switch to use my BCD. So he would need to have enough lift available in my BCD to get us to neutral and then he could begin the ascent. That would mean getting between 7 and 10 kg of air into my wing to make me neutral. In fact you would want to make the casualty slightly positive so if you let go he/she goes to the surface, that doesn't mean that you have to completely empty your own bcd before initiating the ascent, so once my wing was full of air, if you still needed more then you could add it to you own, then beginning the ascent using your own rig to maintain neutral, then when all air is gone you switch to mine.

Thinking about it, how would a flooded drysuit with a small wing be worse than finding someone in a wetsuit OOA ?

If I am the one performing a rescue on you in an OOA then I have a drysuit and a wing to provide lift. If my drysuit is flooded as well then we are not having a good day but are still better off than you being OOA and my BCD is punctured etc. The odds of me having a flood and my buddy having an OOA without one of us calling the dive on single tank non-deco dives is quite remote but is probably a good reason for us to have some redundant buoyancy just incase (dsmbs, lift bags etc).

Sorry to inflict my ramblings on you, but I am keen to learn (it helps keep my knowledge fresh while out of the water). Please correct, debate etc the above.

Cheers

Conor
 

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Camdiver, this is meant in the best possible way so I hope your not easily offended but for me your comments bring new meaning to "Plan your Dive, Dive your plan", keep up the detailed analysis  
 

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Ginger, Irish, sometimes stroppy
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Sorry, boring morning at work, so I babbled. Being a warm water diver I need these little mental excercises to make sure I remember stuff between trips.

Does it make sense though ?
 

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[b said:
Quote[/b] ]Sorry to inflict my ramblings on you, but I am keen to learn (it helps keep my knowledge fresh while out of the water). Please correct, debate etc the above.
Not at all mate, it's a well thought out reply.

I use a wing with loads of lift, about 100lb so I suppose I'm a little biased.
From what you've said, 10kg on your belt, tank, reel, torch, and any other ancillaries, it sounds like you may be approaching 14kg.
There is no guarentee that you will need this bouyancy at the end (lightest part) of the dive - it maybe when you have a full cylinder.

If you're also going to have a backup air supply (you should), then the addition of a pony cylinder will trim this margin even closer.

I cant help feeling that you will be cutting it a little fine.

I'm a firm believer in scondary or backup systems, your wing or suit IMHO should be able to raise you to the surface alone in the event of a failiure in either.

I'm not saying dont use it, just be aware of the potential risks - you obviously are or you wouldnt have made your original post

I think if i were in your shoes i'd try and get hold of a bigger bladder for the setup you've got.

Stu
 

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A short fat well off crap cave diver. Likes wrecks
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<font color='#000F22'>The amount of lead you use should balance your rig with no heavy kit on and less than 50 bar in the back gas and allow you to comfortably hold a 6m stop.

Then you add kit

This is where lift counts on the wing. I have a 2kg tourch two reels, back up tourch 1kg, than twin 12s full of gas and two 7ltr stages full of gas.

As a result when I hit the water I sink like a brick wearing a weight belt.

However should I have to abandon all my kit except back gas and drain all my tanks in the attempt to get up i will at least be able to hold a stop.

So for me my BCD has to cope with me being sometimes 20lb over weight at the begining of the dive so I use a 50lb lift wing to keep my head out of the water. For you I dont think your aditional kit past back gas will amount to much more than two or three KG so you should be fine with 14lb of lift.

ATB

Mark Chase
 
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