Ankle weights

[TSandM]

All I can say is from personal experience. At the beginning, I absolutely needed my ankle weights. Otherwise, I went feet up and had horrible problems controlling my position in the water. The owner of a local LDS laughed at me kindly and told me that I would eventually not need them. I was stung. He was right. I don't use them any more. I'm not sure what changed, except I got better at distributing my weight, and I got much better at diving.

 

[OE2X]

Also it can go the other way, in keeping a diver in horizontal trim so hes not constantly fighting rising feet they can actually REDUCE air consumption as less effort is required to stay in trim.

Excellent point.

 

[bradshsi]

I've been following the discussion on leg weights. So far it's been quite interesting to see the different opinions.

Personally I'm very new to drysuit diving. I did start off with leg weights, but since I changed my fins to slightly heavier ones, I've done several dives without them. I have a Bare HD-Trilam drysuit which has built in gators.


With regard to leg weights and SAC/exertion, my engineering opinion is this :

Ceteris Paribus, adding weight to the end of your legs will increase your work rate. Taking the flutter kick as an example, you are clearly accelerating your feet at the start (and end) of the up and down strokes. Since

Force = Mass x acceleration

and you have increased your foot mass with weights, correspondingly the force you need to exert will increase for any given finning speed.

Since it's your muscles that provide the necessary force and since

Energy consumed = Force x Distance

Thus clearly adding weight will cause additional energy to be expended.



However there other things to consider:

Firstly if we are using heavy fins or boots to achieve correct foot weighting, we are just substituting one form of weight for another. In this case it is incorrect to say that leg weights will cause you to work harder. Your muscles don't care what form the weight is in, only that it's weight....

On the other hand, if we reduce the buoyancy of our feet with a better fitting suit or gators, as opposed to leg weights, then clearly there will be some reduction in your workload. Whether the reduction is significant when viewed alongside the overall workload of finning is beyond my simple analysis.

 

[ScubaGypsy]

That being said NE wreckers are a unique group of divers.

Hmmm, is this meant as a complement or a knock on NE divers?

 

[spectrum]

hhhmmm .. so you're telling me all those studies about how working working muscles need more oxygen is a sham?

When you're talking about moving your two biggest limbs up and down while underwater buoyancy is relevant, not mass. Mass will have a secondary effect but it's not dominant.

Driving a well insulated, buoyant leg down will require energy. In the case of the buoyant leg ankle weights can restore neutrality to the limb letting it just work against the water. If the leg is left buoyant the diver will be doing other muscular things (notoced or not) to remain in trim.

This is like all other scuba gear topics. What works for you works for you. A drysuit diver in 30 sonething F water will have different issues that one configured for comfort in 60 something F. Not to mention getting their choice of suit type to work with their body mass distribution and other gear.

Before diving dry I considered ankle weights evil. Right now they are giving me very nice trim. Or shall I say that with them I have nice trim. I'll continue to explore going without them for the sake of simplicity but if I'm more naturaly balanced with them then so be it.

Pete

 

[Fred R.]

Wow, what a set of posts, nothing like setting a hostile tone….

I am loving this discussion, a bunch of divers who love diving, but have no real experience telling other divers that they don’t know what they are talking about or are incompetent if they use a certain piece of gear….

Well, I’ll just throw in, I use ankle weights, for almost all of my 3000+ dry suit dives, and can dive three one hour 60 foot dives on a single AL 80.

Many of the arguments here, both for and against are specious, yes, putting mass at the end of a lever increases the force needed to accelerate that lever, but if you are still scissor kicking, you are still diving like a beginner, (unless it is an emergency or a race). Intermediate divers can frog kick which reduces the amount of distance the ankle has to travel and thereby reduces the fatigue. Very advanced divers scull, the ankle hardly moves at all, there is no additional work load for having mass at the end of the legs, because the weight is above the moving and motive part.

The ankle weights will actually reduce workload as the diver doesn’t have to spend fin or arm energy to maintain trim.

In point of fact, if you look at the physics, spreading ballast as far from the center of gravity (while maintaining that center of gravity) as possible will work to increase stability in a dynamic situation.

Oh yeah, just to keep the tone going, I am calling anyone with less than a thousand dives a beginner, those with one to three thousand intermediate. :-D

 

[charlieo]

The notion that ankle weights are for beginners or divers who haven't worked out their weight distribution is well accepted. At one time I believed it. I don't use ankle weights with my neoprene O.Neill dry suit no matter what tanks, wing combination I use. Then I bought a Bare HD Trilam. I was very foot floaty. First I moved the wing up on the tanks, then I had the boots changed to turbo soles, then I bought a new wing, then I moved that wing up to the last grommet holes, then I used a lighter undergarment for my legs. Ahh, the lighter undergarment worked. As long as I stay in 55 degree + water and shorter dives it works. If I'm diving cold water and a heavy undergarment I just use the ankle weights. I'm no expert but no beginner either. Considering the amount of work I put into the trial and error, I'm willing to say, just use the ankle weights and learn to live with them.

 

[dbg40]

Again,, IF your gear is properly sized to you, and it should be.
And IF you learn how to properly weight yourself, and you should.
And IF you learn proper technique in shifting air in the suit at will to accomodate your trim at any given time.
You should not need ankle weights. They are a crutch, that hides poor weighting and training. Or poor equipment fit. If you need them, then you most likely have issues that should be addressed. Only my humble opinion.

 

[matt_unique]

Quite simply because the extra increase in effort to move say 2lb when combined with everything else can be so small its insignificant, unmeasurable and have absolutely no real world effect. If the effort reduces your air by 2 seconds on a 45 minute dive you arent going to notice.

Also it can go the other way, in keeping a diver in horizontal trim so hes not constantly fighting rising feet they can actually REDUCE air consumption as less effort is required to stay in trim.

Ive yet to see one single properly researched work that shows a noticable and significant increase in air consumption due to ankle weights.

Ditto....other factors affect SAC FAR MORE than any of this nonsense. Stress, current, anxiety, hunting, pictures, etc., etc., etc. I wonder how on Earth we're able to keep up with other divers on a wreck when wearing ankle weights, two reels, two lights, two slates, and a deco bottle? How on earth are we able to remain horizontal while doing our deco stops? Based on half of this nonsense we would be left in the dust and surfacing with less air. Ha ha ha - turns out we don't....

There are some dives when I wear ankle weights, some dives I do not, my gas remaining at the surface does not change.

Good thing we think for ourselves my ankle weight wearing brothers and sisters!

--Matt

 

[DBailey]

Use ankle weights if you want to; however, there are probably other solutions that would help:

-Drysuit fit in the legs, ankles, and feet.
-Undergarment change at the feet to something that is already compressed.
-Fins that are not postively bouyant.
-Gaitors (shin straps that keep the drysuit from ballooning).
-Rearrangement of your existing weights (i.e. move the center of gravity).

Since I am an engineer, I am a fan of the moment arm. Adding weights at the end of your legs just creates more work. Since water is what, 800 times more dense than air, that equates to more work. It may not be noticeable in reality, but still something to think about.