Weighting Rules of Thumb

[Scubadore]

Anyone have a suggestion for this condition? My wife has trouble with buoyant feet at the end of the dive. She has a tendency to do this with a 3 mil suit, but she bought a 5 mil suit for colder water and this photo shows what happens. She has negatively buoyant fins, has 20 lbs of weight distributed in the integrated pouches and BC back pockets plus she has a total of 3 lbs. of ankle weights. Still she struggles to keep her fins down. I am afraid she will have a sore back if we add too much more weight. See photo. Any ideas?

 

[pir8]

Get different fins.

 

[rakkis]

Have her attach her tank "lower". So that more of its mass goes towards her legs.

Does she really need all that weight in her BCD? Or was it added in an attempt to correct the leg issue?

If she does need it, its more of an issue of placement and balance of her center of mass and center of buoyancy.

 

[Scubadore]

Thanks Rakki, the weights are to keep her down too. Should we be adding more ankle weights (how much is too much?) Would a weight strapped toward the bottom of the tank be helpful? Maybe get rid of the booties and wear socks instead?

 

[Steve50]

anything to get weight lower

In addition to that mentioned;

Thinner booties
Weights low on tank
Weights to weight belt could be lower than intergrated pouches
Less in non-ditchable pockets if they are high up on BCD

 

[Nemrod]

The one I know that may apply is that for a 1/4 inch (7 mil) suit approximately 10% of body weight plus four pounds. Adjust accordingly to exposure protection and tank type and other equipment. I mostly just make an educated guess or get in the pool and work it out. Rules of thumb are generally not very effective given the huge array of equipment and body types. N

 

[Nemrod]

Scubadore, your wife needs a heavier fin, a tank trim weight (about five pounds on an aluminum 80 on the end of the tank), a weight belt on the hips instead of an integrated BC that carries all the weight forward and some pool practice to see what works. Strapping on more and more weight is not the cure for her ailment. Many women have floaty feet. She needs to arch her back more, this helps to bring the feet down.

As an experiment, take all of the weight out of her weight integrated jacket and put it on a weight belt and see if this does anything. N

 

[Scubadore]

She bought Scubapro Jetfin, the black model which she is wearing in the photo. The dive shop owner said it was the heaviest fin. But the heavier booties she has to wear to use those fins seems to be more buoyant than most. I agree about the tank trim and weight belt. I asked what was the limit on ankle weights. She has a total of 3 pounds now on her ankles.

 

[rakkis]

I would focus on moving the tank for now. Don't try to do too many changes at once.

Have her try that out in the water and see how she likes it. Let us know the progress so we can help.

 

[jchaplain]

I had a similar problem when I had all the weight in my bc pockets. I put most of the weight on a belt and that solved the problem. BC's can tend to "ride up" a bit too shifting the cg even higher on the torso.
With most of the weight on a belt rather than the bc it takes a lot of the weight off the shoulders ( and the back,) which is better for the back as well.

John C.