Gear question -- ankle weights

[sabbath999]

Hi.

Biologic is my wife... the following added simply as an FYI...

Her fins are floaters (slightly... Scubapro Twin Jet Max), and she wears a 5mm wetsuit even in warm water (she is extremely fit and athletic, with extremely low body fat which leads her to get cold in less of a suit).

Her boots are 3mm.

She dives with an AL63 tank, and it is set as low as it can be set. She uses a non-integrated vest style BC (Scubapro Classic).

 

[spectrum]

It's all about shifting weight down to move the balance point of your virtual see saw to a point that's manageable throughout the dive. It sounds like you are in the ball park, just a little off center.

1. Drop the cylinder
2. Move weight down. How you do this depends on how you now carry it. If you are wearing a belt you may be able to drop it a little farther down your hips. A small movement can have a big effect.
3. More negative fins, this may allow a corresponding lead reduction too. Since it effects both ends of the see saw it can be a huge help.
4. If you want to try an experiment and are renting AL80s try to use a Catalina instead of a Luxfer. Catalinas are bottom heavy. If you are renting cylinders but see yourself buying soon wait until you have a consistent cylinder to use because that can throw it all off unless you buy what you are renting.
5, Buy a thicker hood

Your recognition of the problem has you 90% of the way to a solution.

Pete

 

[TSandM]

Physics is inexorable. Your balance underwater is going to be a summation of the lift and negative buoyancy of you and your gear. As previously mentioned, Al tanks get butt-light when they empty, and I remember very well being tormented by this when I was a new diver. I no longer have the problem at all, but I did go to Jet fins with spring straps, which are negative. HOWEVER -- I'm not head heavy at the beginning of the dive, either, so I suspect a lot of the adaptation has been learning to use body posture to adjust my balance.

A lot of it is lever arms. If your fins are positive, and your legs are straight, you have a small positive buoyancy on the end of a LONG lever arm. If your arms are negative, and you have them out in front of you, you will have a weight at the end of a moderate lever arm. If you simultaneously drop your head, you will have three things tending to put you on your nose. Arching your back a little bit, bringing your head up so you are looking more in front of you, and bending your knees may help alleviate your problem.

I honestly don't see a huge difference between negative fins and ankle weights, except one is less likely to lose one's fins. If you need a small weight at the end of your legs to counter positive buoyancy there, there's no reason not to use it. I bought one pound ankle weights when I was a new diver, which I no longer use except to sink camera housings and the like. However, if your need for weight is so small that commercial ankle weights aren't available, I suspect this is a problem you could fix with posture.

 

[Teamcasa]

Let us not forget the forum this post is in, New Divers.
Sure, ankle weights will solve a problem but many time the issue can be solved by moving ballast around. When you are new and learning exactly what good trim means, sometimes ankle weights will allow you to experience it and help you practice. As you gain experience, move ballast around and use various type of tanks and wet/dry suits the perfect configuration for each situation will evolve.

Don’t worry about it right now and if ankle weights help, use them. Just remember that the goal of diving is to have fun and constantly improve and learn. Sooner or later, the magic of good trim will appear and you will be giving advise to other new divers.

 

[acwest]

I was just thinking that she should try moving the tank UP, not down, as she only has a problem when the tank is light. This would imply that the centre of gravity of the air in the tank isn't balanced properly, so moving it up a bit should cause changes in the tank pressure to no longer affect her trim. Of course, once she moves it up, she will likely have to shift some other weight down, to compensate, but this would be weight that doesn't go away during the dive...

 

[AndyA]

BioLogic

A question on your fin's and booties. Are the fins neutrally buoyant? How thick are your booties 3mm, 5mm, or 6.5mm. If your fins are neutrally buoyant or close to neutral, try heavier fins also thinner booties will be less buoyant. I would first try the suggestion of slightly moving your tank down.
Andy

 

[sabbath999]

Her fins float a bit (but are not corks), she wears 3mm booties.

 

[Doc]

I was just thinking that she should try moving the tank UP, not down, as she only has a problem when the tank is light..

That is what I originally wrote in post #2, but when I read RJP's post, I edited mine and reversed it.

I would indeed wait until the end of a dive, say 1000 psi, and have a competent assistant move the tank up and down within the BCD sleeve, testing after each move. Be radical, go 2" from the original setting, both ways.

The reason for this? All bodies are shaoped differently, legs longer, torsos shorter, tanks ride differently on all people. The bottom of that tank stays really heavy while the top of the tank gets increasingly lighter. So, for that reason, I would move the tank down for a first attempt. If that was adverse, try the other way.

A lot of good advice above, including the discussion on ankle weights. The best advice so far has been to not add or delete weights, just try moving them first. The easiest "weight" to move is indeed the tank itself.

Without knowing the height of the individual, without seeing the problem first hand, it is an impossible diagnosis over the internet. Often something as seemingly irrelevant as being long waisted can throw a wrench into long distance diagnoses.

Good thoughts about whether there's a weight belt or different positions of weight pockets on a BC, but there are no civillian use fins on the market that are sufficiently positively buoyant to cause this alone.

Additionally, as we become more comfortable in the water, the perceived need for thicker thermal protection eliminates itself as psychological comfort develops. Wearing a 5 mil thoracic and a 3 mil leg might make this problem go away.

Ankle weights are most commonly utilized as "ring weights" that are looped over the tank valve nipple on top, to add extra weight forward and high. This is quite a common application in females, also as a temporary fix for beginners who over inflate their lungs.

Ankle weights by their design, utilizing 3/4" Fastex buckles, are obviously not constructed with fast or obvious ease of ditching as a feature. With this in mind (many years ago, before there was any such thing manufactured), we used ankle weights designed for exercising. These differ only in that they are heavier, they are naugahyde, and they have Fastex buckles of 2", making them a lot easier to take off.

Before you run out and buy some, try something else at that 1000 psi test time. Take along two 1# weights and try slipping them into your bootie ankles. They won't stay in, so don't ever assume this is a permanent fix, but if you want to try before you buy- there you have it.

 

[NOVIZWHIZ]

I was in my LDS one day and one of the workers yelled at the boss as to what he wanted to do with those **** ankle weights - boss yelled back TOSS'EM - ain't sold them in a year, tired of looking at them.....I've been wearing them every since and like em...

 

[BioLogic]

Thank you all for your time and thoughts! I'll try out what I can this weekend in the pool and see what works best.