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Weight for dynamics

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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Apnea Carp
Oct 11, 2003
I would be interested to know how much weight is normally needed for dynamics. Everyone else seems to use very little or none at all, but I use 4kg with a 3mm suit. I tried to do some dynamics with my 5mm smoothskin and 4kg of weight, but it was impossible to do more than a few metres with or without fins, as I was using a huge amount of effort to stay under. I splashed along the surface, kicked one fin off and made everyone laugh!

I read in another thread that Tom Sietas used 10kg of weight for his dynamic record, so it couldn't be a bad idea.

I like to be slightly negative at 3m and slightly positive at the surface, both with full lungs, when doing dynamics. This has never caused any problems - sometimes people ask if I am ok with all that weight, but there has never been any problem with getting to the surface, even when I am very tired.

The only disadvantage of needing so much weight is carrying it to the pool. I learnt an important lesson - it's hard to do statics after carrying a heavy bag around for a long time! :duh

I think in simplest terms you want to weight yourself so that
a) you're perfectly neutral at your target depth (usually 1-2 meters)
b) you're perfectly balanced

To achieve a), you simply have to grab some weights and go float in the pool. Remember to inhale as you would in an actual dive. Once you have figured out the amount of weight you need (adding some, loosing some untill you neither sink or float in your target depth), you can proceed to b).

Now b) is a lot trickied. Adding 100g to your neck ballast can suddenly tip you off balance. Since your center of gravity is roughly at your mid-section, adding ballast to the neck makes big leverage, therefore tipping you on your nose.

I suggest you first put all the weight on a belt. Then go float in mid-water and kick off from the wall and try to glide straight. Don't kick or move. Most likely towards the end you will start to tilt upwards, head up, feet down. Now move some weight (say 1 kg) to your neck and try again. Repeat untill you will glide perfectly straight.

To achieve perfect balance you will need very small weights and for the tuning part preferably some that are easy to attach temporarily. I'd say the largest usefull weight is around 1 kg. But you should have plenty of 100-500g weights. You can device a "temporary neck ballast" by just attaching small weights to a collar of sorts with duct tape or something (bi-cycle inner tubing is popular). Once you know the actual weight you need, you can go ahead and build a proper neck ballast.

If your wetsuit pants/fins float alot, you might want to experiment with some ankle ballasts as well...

Being in perfect balance makes a huge difference, as anyone who has gone trough the trouble of finetuning it will tell you. If you have ever scuba dived, you will know what a pain it can be to be even slightly off. Struggling to keep straight for 40 minutes watching those annoying, experienced divers glide throught the water so effortlessly with just a few kicks now and then.

Anyway, there's not really any short cut, as each individual is different, you must find out for your self.

Just to give some estimate, I use 1.2kg on my belt and about 1.5 kg in my neck WITHOUT a suit. This is when I pack fully. The reason I don't dive with my 5mm elios currently in the pool is, that I don't have enough weights to even get comfortably to the bottom, and I've loaded over 8kg in there while trying :) Now that I've given this fine lecture, I should take my own advice and balance my self better. I'm far from perfect balance, but still having those weights makes a huge difference to having none...
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Jome, thanks for all the advice - next time I go to the pool I'll give it a try! :)

I'm 5'7" and 140lbs, and I use 4 lbs neck weight without my suit for dynamic. I went through the same process that Jome describes, and found that neck weight only worked best for me. I can't use my suit in the pool either because I don't have enough weights to offset the bouyancy of the suit! However the same process would work with a wetsuit as without.

Happy Practicing!
I tried using 7kg of weight on a belt with my 5mm suit. The amount of weight felt right, but it was not well balanced and I could only do about 20m with or without fins. I will try using neck and ankle weights.

Sorry, are you talking about Dynamic in pool?? It´s to cold the pool where you train?? Sorry I can understand the neccesity of suit in a pool. Can someone explain me why you use it??

Best regards
Some people find long sessions in a pool too cold. I think Lucia has mentioned before, that she get's really cold. Even I get cold if I stay in very long and I think I have pretty good tolerance to cold. It also depends on the temperature of the pool...Even a few degrees make a big difference. It's pretty hard to relax if your body is spasming from the cold. And even if you don't feel cold, you body is losing energy very rapidly to heat production. Whether or not that makes a difference varies from person to person I guess.

Another nice thing about using a suit is that it allows a lot of weights and thus greater momentum. Especially in no fins dynamic, some people find it useful, since they can utilise kicking from the wall for a longer glide. Some claim that a opencell suit is even more hydrodynamic than skin. I don't know about that, but in a top competition every inch counts, so why not...

5mm suit is too thick for the pool though, I think 3mm or even less would be ideal. Finding the right balance with a suit is much trickier than without, since it floats in all the wrong places :)
I'm lucky with my pool !!! I never tried to swim with the new designed special clothes for swim, may be can help in order to avoid the use of lot of weight. I agree that 5 mm for pool it´s a lot but it´s really hard to train apnea with cold. Maybe the suit designed for triatlhets allow better the movements for dynamic without fins.

jome said:
Some people find long sessions in a pool too cold. I think Lucia has mentioned before, that she get's really cold. Even I get cold if I stay in very long and I think I have pretty good tolerance to cold. It also depends on the temperature of the pool...Even a few degrees make a big difference. It's pretty hard to relax if your body is spasming from the cold. And even if you don't feel cold, you body is losing energy very rapidly to heat production.
That is the reason why I wear the suit in the pool. I don't get too hot even in 27C water with a 5mm opencell suit. I find it difficult to do dynamics when I am cold, because I can't relax on the surface for long without shivering, and if I try statics..... :waterwork

I am so happy with the suit - it makes a huge difference to my training.

I’m a cold blooded person who has to wear a suit in a pool, although my 3mm, open cell inside, is plenty in even the coldest pools. If it’s not real cold I use a 1.5mm, which I find is a easier to weight.

If your wetsuit pants/fins float alot, you might want to experiment with some ankle ballasts as well..
This is an interesting subject for me.

My fins come up a lot. Kirk Krack told me that if my fins come up and I am arching my back then I actually need more weight on the neck. This is because I’m trying to compensate for the buoyancy of the upper body by swimming down with the fins and legs. I have tried just about ever weight combination, except ankle weights, and although a good neck weight takes the arch out of my back, the fins still come up. I saw some video of me doing a dynamic and I think I just plain bend my knees too much and use my hamstrings and thighs instead of the gluts and abductors.

I believe I have a lot more potential in dynamic (my pb is only 85 meters) if I could just get my swimming technique better and quit using so much energy. For example I have done over 3 minutes in dynamic walks holding my arms above my head in the dive position and recently did 2:30 with an exercise cord strapped to my ankles to simulate diving effort. Just 1:30 in the water would put me well past 100 meters.

Ankle weights don’t seem like the best thing because they would take extra muscle effort since the legs are moving, but if they cured my bent knees, maybe they would be worth it. Does anyone out there uses ankle weights in dynamics?
Im starting to use a surfing spring suit which i have cut the arms off . It provides warmth for my torso and the flexibility for my arms to do dynamic no fins .Im wearing a 6.5 lb neck weight and 5lb around my waist . With full packing i am perfectly weighted and it feels great getting the extra glide . Im down to an easy 4 strokes no fins for 25m. I think i will make another neck weight for nomal inhale aswell. Cheers Nathan Watts
I believe there has been an thread on this board earlier about how to make a neck weight. Im very interested in making one. I dont want to use a bicycle lock.:)

Please describe how to make one.. I really need it.

When im fully packed, I float up from 4m really fast.. I even float up when holding a rescue doll. :wave
I would never use ankle weights. It takes too much effort to move them with every kick.

Keep in mind that although some weight will give you extra momentum and a better glide, you actually need more energy to start the glide i.e. you need to kick harder at every turn to achieve the same speed off the wall.

I use a weight vest with pockets so you can adjust the total weight, made by SEAC SUB. The way to adjust the weight is to start a dynamic with exactly the same amount of air in your lungs that you would put during a max dynamic. Then, right after kicking off the wall, STOP every movement and glide until you stop moving. Maintain the position and wait and see what you body does. If you go towards the surface, you might want to add a little weight. If you sink, take some weight off.

You don’t want to be totally neutral but very slightly positive. Once you start your breath hold, you burn O2 and produce CO2. CO2 is denser so at the end of your dynamic you’ll be LESS buoyant. So if you start a little positive, you will be about neutral at the end.

If you can’t find a weight vest, I would use a neck weight COMBINED with a weight belt around my waist and experiment with the amount of weight on each one. Our lungs are not in our throat :)

Panos Lianos
Athens, Greece
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My local scuba shop sells these little 0.5 lb (225 gram) weights that fit on 1" (25mm) webbing. So I had them whip me up this snazzy neckweight. Actually I had them whip me up two... this one after I "left" my first one on the bottom of the lake ;)



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I heard that the center of rotation for a diver is approx. at the navel. So putting the weights further away from there would mean the same effect with less weight. Wouldn't that then mean that neckweights should be a little better than a vest (given that the diver doesn't want to use the momentum-effect to a max) ?
Just a thought.
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Exactly. That's why I suggested ankle weights earlier (haven't tried my self). Even a little weight at, say the foot pocket of your fin, would have the same effect (balance vice) as a largish weight nearer the pelvis. The same goes of course for the neck.

Without a suit, you might not even reach perfect balance without losing too much buoyancy if you use a vest etc.

Someone could even do the math, I'm far too lazy and a bit rusty on my physics. Shouldn't be that hard though.

I've also seen a lot of divers diving with a neck weight only or too much neck weight and they glide in a very strange position. Head down, feet up. That's another reason why I thought of ankle weights. Personally I use a neck weight and a belt (without a suit) and rech "reasonable" balance, but I bet a few hundred g on the fin wouldn't hurt. Sure it would make the fin harder to raise up, but then again, easier coming down (where the bigger propulsion is anyway). Just an idea, maybe worth trying...But the raising feet problem is not really a problem without a suit, since your bare legs are more or less neutral. But with a suit it's worse. You counter every other body parts extra buoyancy with a weight, except the legs/feet. Obviously it's going to tip your feet up.

If you put all the weight on your belt, you "jack knife" (waist going down, feet and head up, seen this plenty of times, looks horrible). If you use a neck weight in addition, you will drop on your nose (head and waist going down, feet up). I really don't see any other way to reach perfect balance with a suit than having some ballast on your feet or perhaps a fin that sinks...Of course the effect is lessened with movement and with a fin directing the water flow, the effect is not as dramatic as being off balance at the neck/head.
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The problem with ankle weights is that you do not only have to use energy for a forward motion of the weight together with your body but for lifting them up and down with your feet as well.
As I (!) understood it, head down/feet up is the typical picture of someone with too little neckweight. The explanation I got was that they are trying to compensate for a floating upper body by finning downwards. This again creates the strange head-down-feet-up position.

Just my 2 cents though.

I must say that at least according to my experience, Veronika is correct in saying that head-down posture is the result of too little neck weight. In dynamic, it is useful to place the weight on neck, because there it counteracts the rotating force created by buyoancy of lungs that are situated in the front of the mass center of a typical human body.
jome said:
If you put all the weight on your belt, you "jack knife" (waist going down, feet and head up, seen this plenty of times, looks horrible).
That is what was happening to me! :D
What I need is to experiment with lots of weights and find out what works best for me.

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