How much weight do you use??

[Davey Willo]

I'm just wondering what the average weight carried by everyone is....

The reason I ask is that I've alway's felt that I was a little overweighted, as I could sink like a stone once I emptied all of the air from my BC, and after diving with as little as 6 kilos in Cyprus I decided to try and reduce my load in the UK.

Now I realise that theres a big difference when wearing a shorty wet suit to a full membrane drysuit with undersuit, but how much of a difference??

When I went to Cyprus, I took my own BC, fins, mask, regs and snorkel.. The dive centre gave me an 8 kilo belt which felt just right.... no problem in getting down once I'd emptied the BC... I didn't feel overweighted at all and walking about fully kitted was a doddle (unlike walking about in the UK)For my Zenobia deep dives they reduced my belt even further down to 6 Kilo's and so this got me thinking... Did I really need to carry so much weight back in Blighty??

I decided therefore to reduce my load to 11 Kilo's yesterday, and found I was too light, yet the only difference from Cyprus was my membrane drysuit and weezle undersuit, yet I'm carrying 3 to 5 Kilos more... does this sound right? can these two items require so much compensation, especially as a 5mm Shortie must still have a certain amount of added bouyancy.

Now I always squat and squeeze all of the air out of my suit before I even kit up, so as not to trap any air with my belt, I keep the auto dump wide open too. I'll put a little squirt of air into my BC before entering the water, then when ready to go down I hold the hose above my head and dump... that's my usual routine which usually see's me down ok.... Now with 11 kilo's of combined weight (belt and ankle weights) I couldn't get down at first.... my head went below the surface but that was about it... I had to turn and fin for the bottom hoping to grab a rock or two when I got there, but once I'd gone down a bit I was ok.... Now this tells me that I had air trapped somewhere because obviously the increasing pressure made me less bouyant... once I was down I felt perfectly weighted and had good control, in fact I kept adding to my suit to stop the squeeze and cold, without sending myself upwards....

The next problem arose as we slowly got into shallower water. I'd already started dumping air in preparation for the decrease in pressure, yet I still started to rise uncontrollably, I was having to fin down and grab onto some kelp, I pulled myself into an upright position to make sure there was no air trapped in the lower half of my suit, wiggled and jiggled a bit to move any air and kept depressing the auto dump button, still hanging onto the kelp I was then curled up into a feotal position squeezing every nook and cranny in my suit and pulling on every available dump in turn. Yet I have to say, that if I hadn't had the kelp to hold onto I would of definately popped up...

So.... one can assume I was underweighted.... but how much should I be carrying?? I realise that its not an exact science, and that many different things effect bouyancy including physiology, but what I'm wondering is....
'What is the average, dry suited UK diver carrying?'

And knowing that I'm struggling to first get down, and then also stay down in the shallows, yet have no problem below say 10 metres.. trapped air!! yes, but obviously I'm going to have to account for it
'How much do you think I should add?'

Dave.

[andy2tanx]

Ok quick answer which will have to do for now....
14 stone, twin 12's, wooly undersuit and otter neoprene drysuit.
12 kilos.
Without the undersuit, 10 kilos.
3mm wetsuit, long johns and jacket, with twins, no weight belt at all.

[Jay]

Just been going through the same thing recently - currently dive with 12kg but I'm gonna give it a go on Thursday with 10kg to see how it goes (also bought a weight belt and got rid of the shitty integral weight suicide system). Your undersuit will make  quite a large difference due to the volume of air trapped within it.

Regards

[Davey Willo]

Well it doesn't seem that I'm too far away then...

At the moment I have (on my belt) 2 large weights and one small one, I'm going to take off the small one and put it in one of the rear trim pockets on the back of my BC and then add another small one into the other trim pocket. This should add between 3-4 lbs of weight (according to my crap kitchen scales) putting me in the region of 12-13 Kilo's total, with approximately 18 lbs of dumpable weight still on the belt.... (sorry for the mix of units and bad spelling) If you wondering why I want it off my belt, its cos it absolutely knacks my lower back and siatic nerves when I'm humping a long distance...

My undersuit is a Weezle Extreme which is very compressable (fits into a football size bag) and I also look vacuum packed before and after the dive, but obviously its trapping more air than I imagined... I suppose a good test would be to dive without it, but I wont even think about that for a few months yet.. <Shudders at the thought>

Jay..talking about a suicide system, my mate from the dive club is so paranoid about losing his belt and doing a posiedon missile impression that he has had a set of braces made to attach to the belt.... no way to dump it AT ALL!!! ... its on and its staying on.. :surprised:
I cannot convince him that its preferable to be on the surface waiting to be airlifted to a chamber than nailed to the seabed.. well thats my humble opinion anyway...

[Jay]

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Originally Posted by [b

Quote[/b] ]Quote: from Dave Williamson on 9:53 pm on Feb. 19, 2002
its cos it absolutely knacks my lower back and siatic nerves when I'm humping

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You and me both mate!

Regards

[divedog]

Hi all .. just thought I drag this one out of the books for you !!!
Buoyancy
Archimedes Principle
Some objects, when placed in water, float, while others sink, and still others neither float nor sink. This is a function of buoyancy. We call objects that float, positively buoyant. Objects that sink are called negatively buoyant. We refer to object that neither float nor sink as neutrally buoyant.

The idea of buoyancy was summed up by Archimedes, a Greek mathematician, in what is known as Archimedes Principle: Any object, wholly or partly immersed in a fluid, is buoyed up by a force equal to the weight of the fluid displaced by the object.

From this principle, we can see that whether an object floats or sinks, is based on not only its weight, but also the amount of water it displaces. That is why a very heavy ocean liner can float. It displaces a large amount of water.

Archimedes principle works for any fluid, but as divers we are mainly concerned with two different fluids: fresh water, and salt water. We need to think of fresh water and salt water as two different fluids because equal volumes of fresh water and salt water do not weigh the same. For example, a cubic foot of fresh water weighs approximately 62.4 lbs, while a cubic foot of salt water weighs approximately 64 lbs. The extra weight is because of the dissolved minerals in salt water.

Let's take a moment and look at an object in water and Archimedes Principle. If you place a 1 cubic foot object that weighs 63 lbs into fresh water, the object is displacing 62.4 lbs of water, but weighs 63 lbs. This object will be negatively buoyant - it will sink. It is however being buoyed up with a force of 62.4 lbs, so if we weighed it in the water it would only weigh .6 lbs.

If we put the same object into salt water, it would still weigh 63 lbs, but would be buoyed up by a force of 64 lbs, and it would float. It would be positively buoyant in salt water. To make the object neutrally buoyant in salt water, we would have to add 1 lb of weight to the object without changing its size (without changing is displacement). Then it would weigh 64 lbs, and be buoyed up with a force of 64 lbs, thus being neutrally buoyant.

Let's expand on this and look at an example of putting these ideas to work in a real situation. Suppose you know that a boat had lost an anchor weighing 100 lbs. Measuring a comparable anchor, we find out that the anchor displaces 1/2 cubic feet of water. We will also assume that the anchor was lost in a fresh water lake. You do a dive and find the anchor and want to bring it to the surface but the only resource you have available are some 1 gallon milk jugs. How many would you need to tie on to the anchor to float it to the surface?

At this point we need to do a little simple math. We know that a cubic foot of fresh water weighs 62.4 lbs, so the anchor displacing 1/2 a cubic foot of water would be buoyed up with a force of 31.2 lbs. Let's round this to 31 lbs for simplicity. This means our anchor that weighs 100 lbs on land will weigh 100-31 or 69 lbs in the water. We now know we need enough 1 gallon milk jugs to generate 69 lbs of lift.

Perhaps you remember the old expression &quot;A pint a pound the world around.&quot; This refers to the fact that a pint of water weighs about a pound. Since there are 8 pints in a gallon, we know a gallon of water must weigh about 8 lbs. Since we know a cubic foot of water weighs 62.4 lbs, this means there are about 8 gallons of water in a cubic foot. Let's put it together and solve our anchor problem.

If we need 69 pounds of lift, we divide 69 by 8 lbs per gallon to learn we need 8.625 gallons of water displacement to make the anchor neutrally buoyant. This means, we could fill 9-one gallon milk jugs with air to lift our anchor.

Let's try another. A 3 cubic foot object weighing 400 lbs is dropped into the ocean. How big of an air lift bag (in cubic feet) would you need to lift the object?

First we determine that a 3 cubic foot object in salt water would have 3x64 lbs of lift, or 192 lbs of buoyant force. If we subtract 192 from 400 we get 208 lbs. This means we need to generate 208 lbs of lift to make our object neutrally buoyant. We then divide 208 (the objects in water weight) by 64 (the weight of a cubic foot of sea water) to get 3.25 cubic feet of displacement is needed to make the object neutrally buoyant. Thus, we would need at least a 3.25 cubic foot air lift bag.

[ScubaBabe]

I refuse to answer this question - didnt you know its rude to ask how much weight a lady carried!! :tong:

[divedog]

We wouldnt be so rude to ... why us yorkshire gentlemen should ever consider it is beyond me ... After all diving is a dangerous sport let alone bringing in the male / female politics - I dont wanna die young !! :reaper:

The answer to the wieght thing is simple... you find your own wieght.... everybodys bouyancy is individual in comparision to the person, size, displacement, equipment, kit config - if everyone was the same size, wieght - wore the same kit ... well it would be easy... Sorry Dave but youre gonna have to get your butt to a staging platform or a shallow sheltered site taking into consideration whether you in fresh/salt water to sort it out m8 :drown:

[ScubaBabe]

Divedog

Just tried to IM you on aol when your on the board but it says your not on AOL - I'm confused!!!

[Ammers]

Dave

I had the exact same problem with low back pain due to a bike smash over a year ago. I was out for around 12 months and on starting diving again had to completely rethink my kit. Nothing hurts like a weight belt around your waist!! I have no weight belt now and have moved all my weight to different places. I use the old scubapro jet fins with spring straps and they are 5 pounds alone. On the twinset I have weight pouches bolted on so the weight is evenly distributed, you can use V weights too which are ditchable or pouches clipped on either side of the belt of a wing. BCDs and weight belts are NOT the way to go with back problems and indeed can make the problem worse. I have had various diving medicals etc and was told not to dive because I was straining the lower vertebrae..so the only answer was to completely reconfigure. Never say die!
Result - now I can carry twin 15s with two stage bottles with NO back pain!! Once you move to a twinset it's infinitely easier, I promise, the weight sits properly distributed and you can drop some weight because of the added twin weight. Be careful about how much you are dropping, every 10 or 20 dives you should try dropping a few pounds of lead off. If you can float at eye level with all air dumped holding a normal breath then you are correctly weighted. If you can stay down at 3 metres with 50 bar in tanks then you are correctly weighted. It all takes time and practice and patience but it WILL come eventually and the &quot;bouyant&quot; feeling will go away. Mind power plays a big part too...when you are dropping down, just exhale and relax, finning and struggling is best avoided and will make you exerted and use more air on the descent..get in shallow water and use the whole time to mess about with weight..it's the only way!