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Discussion Starter · #1 ·
I'm trying to get my weighting sorted out now I've started diving twins. On my first proper saltwater outing recently I found myself extremely uncomfortable, hardly able to hold a 3m stop with X kg of weight and 1.5kg ankle weights, so on my next otherwise identically kitted dive I ditched the ankle weights for a 3.5kg P-weight to increase my weight by 2 kg. Like this I could hold the stop easily, but I felt very heavy (more than 2kg overweight, imho) throughout the dive - plummeted like a stone on descent, couldn't really get comfortable underwater. Apart from the weight, very little else was different at the end of the two dives - I would say that I was equally (marginally) tense on both of them due to feeling like I was under- then over-weighted, both were in salt water, tank pressure was pretty much the same at the stop.

I'm a big man and I've always carried a remarkably large amount of weight but I'm keen to lose it if I can; I know it'll go down as I get more relaxed with my new setup, but I'm nervous about not being able to hold a stop when it actually matters, and of course feeling tense about it makes it worse...

Any thoughts, apart from the obvious 'try losing 1kg and see how it is' one? Or is obvious a good place to start?

(BTW When I say i carry a lot of weight, I've now got a P and a V weight, and still need to carry extra in weight pockets. With Heiser heavy 12's. :eek:mg: And I wonder why no one helps me back onto the RIB.)

This is my first post apart from my introduction (hello!) - thanks in advance.:)
 

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A Moderate from 04/01/07-24/12/12
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Hi Nick,

There is a truism once quoted on this board, that "you need what you need" so whether that's a lot or a little is pretty irrelevant so long as it's accurate.

In my experience most people overestimate what they need because they actually don't like the feeling of neutral buoyancy.

Try searching the archives for an article by Mark Powell on buoyancy control which included a piece on proper weighting.

I think this is best achieved with someone else's help though, and changes should be made in small steps. When you said you felt uncomfortable on your stop you did not say how much gas you still had in your wing or whether you were finning upwards or downwards during the stop. That would give additional clues. I think that changing your overall weight in chunks of 2kg is going to make it hard for you to get comfortable with it.

If I were you I would go back to basics, get 30bar in your twins, dress up fully and go in a swimming pool with the weight you normally use minus 3kg. Put as much of the remaining weight as you can on a weight belt in 1 kg chunks. Then dump the gas from your BC till you are firmly rooted to the bottom of the pool, wait a minute or two to chill out and make sure you are calm.....it's quite likely that in hte heat of the pool environment you may well be puffing a bit so take this time to chill. When you are happy you are relaxed take 1kg off, wait a minute or so to get used to that and if you are still rooted to the bottom then take another 1kg off and repeat till you feel that breathing in just lifts you off the bottom but not in a way that sends you rocketing to the surface. Try swimming round the pool and you should feel quite light but not uncomfortable.

Add the 3kg back on when you go sea diving then stick with it for a good series of dives then re-evaluate. If you still feel too light then either you did not do the weight check properly or there is something else causing the problem.....e.g. you are not effectively dumping gas from BC or suit, or you are breathing too heavily which can then be addressed separately.

HTH
Mal
 

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Hi Nick,

There is a truism once quoted on this board, that "you need what you need" so whether that's a lot or a little is pretty irrelevant so long as it's accurate.

In my experience most people overestimate what they need because they actually don't like the feeling of neutral buoyancy.

Try searching the archives for an article by Mark Powell on buoyancy control which included a piece on proper weighting.

I think this is best achieved with someone else's help though, and changes should be made in small steps. When you said you felt uncomfortable on your stop you did not say how much gas you still had in your wing or whether you were finning upwards or downwards during the stop. That would give additional clues. I think that changing your overall weight in chunks of 2kg is going to make it hard for you to get comfortable with it.

If I were you I would go back to basics, get 30bar in your twins, dress up fully and go in a swimming pool with the weight you normally use minus 3kg. Put as much of the remaining weight as you can on a weight belt in 1 kg chunks. Then dump the gas from your BC till you are firmly rooted to the bottom of the pool, wait a minute or two to chill out and make sure you are calm.....it's quite likely that in hte heat of the pool environment you may well be puffing a bit so take this time to chill. When you are happy you are relaxed take 1kg off, wait a minute or so to get used to that and if you are still rooted to the bottom then take another 1kg off and repeat till you feel that breathing in just lifts you off the bottom but not in a way that sends you rocketing to the surface. Try swimming round the pool and you should feel quite light but not uncomfortable.

Add the 3kg back on when you go sea diving then stick with it for a good series of dives then re-evaluate. If you still feel too light then either you did not do the weight check properly or there is something else causing the problem.....e.g. you are not effectively dumping gas from BC or suit, or you are breathing too heavily which can then be addressed separately.

HTH
Mal
i have to agree with mal.
remember if you have the right weight at the end of the dive you will feel quite heavy at the start.
5000lts of compressed gas does weigh quite a bit.
 

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I think Mal has covered it quite well but there is one thing that I'd like to add ...

Like this I could hold the stop easily, but I ... plummeted like a stone on descent, couldn't really get comfortable underwater.
The thing that I found when moving over to twins from a single was that the change in weight of gas is increased - with a single 12 you have approximaltely 3kg of gas and with twin 12's about 6kg - so at the beginning of the dive you're always going to be a bit overweighted. It's just making sure you're not underweighted at the end :)
 

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Narked at Zero - given the weight of gas in twins (5kg+ often) you'll alweays be noticeably heavier at the start of a dive than in a single.
You may need to put some (more) air in your wing and let it out during the dive to compensate.

It is surpising what lead you may need to sink, my logbook records the following..

twin10s, old undersuit, freshwater 4lbs/1.8kg, seawater 8lbs/3.6kg
twin10s, new undersuit (300gsm, lovely) seawater 12lbs/5.5kg
twin 12.5s (lightweight faber?), new undersuit, 18lbs/8.2kg *

* this seemed an awful lot to me, but on a dive with less I was vacuum packed, wing sucked dry, upside down & finning to prevent a runaway ascent, so I can't argue with that.

Iain C
 

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Narked at Zero
It is surpising what lead you may need to sink, Iain C
remember you cylinders may be haver or lighter than your mates so it becomes harder to compare your weighting to the next diver.

Ive only started diving twins last year it took about ten days diving to get comfortable. Now I am messing with where I want the weight to be.

Mal advice seemed like a good plan :)

I purged my down from 30 to zero bar on my gauge and could still hold a 1 meter stop. on filling them they had 9 bar in them so my gauge is a little out :)


DAvid
 

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Right here is the scores on the doors for me in the sea:

Single 12 and Buddy Commando, 100g undersuit: 28 lb
Single 12 and Buddy Commando, 300g undersuit: 36 lb (eek)
Twinset and 100g undersuit: 16 lb
Twinset and 300g undersuit: 24 lb

I find I trim perfectly out in a twinset with all my lead round my waist. With a dumpy 12 I need 8lb cam banded at the top of the cylinder, with a tall 12 lead on my waist is just fine. Twin 7's are slightly neck heavy, twin Faber 12.5 (bloody heavy) trim perfectly.
 

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Finless: You couldn't invent him...
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I'm trying to get my weighting sorted out now I've started diving twins .................................................... (BTW When I say i carry a lot of weight, I've now got a P and a V weight, and still need to carry extra in weight pockets. With Heiser heavy 12's. :eek:mg: And I wonder why no one helps me back onto the RIB.)

This is my first post apart from my introduction (hello!) - thanks in advance.:)
Hi, the common consensus/average for someone of my build diving twin 12s is 4kgs of lead. I use 8 + ankle weights.

I'm afraid the only way you can know for sure is to get in some shallow sea water (with an on shore/harbour wall assistant) with nearly empty cylinders (30 bar in each) and all your normal dive equipment and make sure you can comfortably hold your 3 mtr safety stop.

Like you I am concerned about diving with too much weight ............ not that I'm not comfortable as I am but more that I like to be 'doing it properly'. I went to Eastbourne marina, dumped all my gas after a quick swim round and decided I was happy just as I was. I evidently like a bit more gas in my dry suit than most people ................ that's 'cause they are perverts and/or masochists because they like the genital squeeze!

Not a bad title for a song? "I've got the genital squeeze!"?
 

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Discussion Starter · #15 · (Edited)
Thank you all for your responses, especially Mal for your detailed reply.

...When you said you felt uncomfortable on your stop you did not say how much gas you still had in your wing or whether you were finning upwards or downwards during the stop...
35 bar in the twins, no air in the wing that I could find, I was wriggling around all over place to make sure there wasn't any trapped anywhere, and was experiencing Finless' copyrighted Genital Squeeze (would that be a Michael Jackson song, do you think?) off the drysuit. I ended up combining sipping tiny amounts of air and finning downwards when it all got too much. It wasn't a deco dive, thankfully...

...changes should be made in small steps...
...I think that changing your overall weight in chunks of 2kg is going to make it hard for you to get comfortable with it...
The overall problem I've been having is not yet finding any kind of constant by which to gauge what works for me, and that's making me change my weighting in a really crude way:

I've done weight test days at Horsea (brackish water, usually -1kg for me), and under a pier with exactly the same kit configuration and came to the conclusion that I was a tad underweight at 30 bar in salt water with 8kg, so when I first went out to sea I got hold of a 4.5kg V-weight and put 6kg in my wing weight pouches, total 10.5kg, just to be sure. As I was kitting up I impetuously grabbed my ankle weights (just to be double sure - nerves I guess) which added another 1.5kg to me overall. Total 12kg. That should be stupidly overweight, and yet I couldn't hold 3m at 35 bar on the second dive. So now I'm 8kg P and V weights, and 6 kg in my pouches: total 14kg with heavy Heiser 12s, or in other words 1kg more than I am with a 15 ltr steel and pony. :confused: :confused: :confused: :confused: :confused: :confused: :confused:

Of course it's very early days with the twins and I'll get there eventually, especially as I get more relaxed. I'm just very confused by all that weight, I thought I'd be shedding loads going to twins, and not just of money. I think I'm going to follow Mal's procedure, a bit more of weight testing at Horsea required. Maybe cutting an arm off, or if that failed (and only as a last resort obviously) leaving my lucky bouncy castle on the surface would help. :wink:

Thanks again everyone,

Nick
 

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I'm just very confused by all that weight, I thought I'd be shedding loads going to twins, Nick
Don't worry - you need what you need.

Just because the twin set weighs more it does not automatically mean that you need less lead - reason being displacement.

As an example (ignore the weights themselves it's the relation between the weights that I'm trying to show), all for sea water with the same drysuit and undersuit:
single 12/232 - 7kg
single 12/300 - 5kg
twin 12/232 - 5kg
twin 16/232 - 5kg

As can be seen although the weight of the rig increases the weight needed on the belt does not change much.

Hope this helps.
 
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