Weight problem

[NarkedAtZero]

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. 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.

[Mal Bridgeman]

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

[Scubee]

Minor thread hijack and stupid question alert.....

I know what a V weight is, but what is a P weight?

[Buoyant Babe]

Originally Posted by Scubee

Minor thread hijack and stupid question alert.....

I know what a V weight is, but what is a P weight?

I think it might be a weight that sits in the channel of your backplate instead of between your cylinders. Someone much better informed will be along soon though I'm sure

[Scubee]

Originally Posted by Buoyant Babe

I think it might be a weight that sits in the channel of your backplate instead of between your cylinders. Someone much better informed will be along soon though I'm sure

Thanks, BB -

Blimey, I don't thnk there would be enough room in my channel for much weight.

[Mal Bridgeman]

Originally Posted by Scubee

Minor thread hijack and stupid question alert.....

I know what a V weight is, but what is a P weight?

Good pics here

HTH
Mal

[Scubee]

Thanks, Mal.
BB was right!

[mala]

Originally Posted by Mal Bridgeman

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.

[The Duck]

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

Originally Posted by NarkedAtZero

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

[IainC]

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