Looking for 'Balanced' BP/W weight distribution advice

[formernuke]

I am not sure that this applies 100% directly to a 7mm wetsuit, since it is not a body of gas like a shell drysuit, but rather is made of compression resistant neoprene which is much denser than air.

I believe the amount it would compress would be dependent on the particular wetsuit's neoprene quality and density. Surfing wetsuits are made from less dense neoprene and do not perform as well at depth as a quality scuba wetsuit which is made of more dense neoprene.

I'm not sure it would apply because at some point the suit won't compress anymore. Not sure when that happens though....
Anyone got a chamber in there basement and a spare 7mm they can use to satisfy my curiosity?

 

[Atlantic Explorer]

You could dive a steel 12l cylinder and reduce your weight belt lead, can also transfer 1kg blocks from belt to the harness with a couple pairs of triglides if you want less ditchable weight. Simple.

 

[MichaelMc]

I'm not sure it would apply because at some point the suit won't compress anymore. Not sure when that happens though....
Anyone got a chamber in there basement and a spare 7mm they can use to satisfy my curiosity?

From prior discussions on suit compression, scuba and more industrial scuba wetsuit material does resist this, past some compression point within the rec range. But you also can tip over to the point where the remaining air size is not more significant than the fact that the actual rubber is denser than the water. A suit of mostly solid rubber with only tiny air bubbles left is negative. To actually know, you would need to measure, or understand the details of the material.

ETA: As I understand some suits with sturdier rubber surrounding the bubbles start out with bubbles at higher preasure than atmospheric.

 

[Thunter96]

I am not sure that this applies 100% directly to a 7mm wetsuit, since it is not a body of gas like a shell drysuit, but rather is made of compression resistant neoprene which is much denser than air.

I believe the amount it would compress would be dependent on the particular wetsuit's neoprene quality and density. Surfing wetsuits are made from less dense neoprene and do not perform as well at depth as a quality scuba wetsuit which is made of more dense neoprene.

100% agree it is not going to be a linear relationship with the neoprene "reinforcing" the air bubbles, and it will depend on the specific neoprene, the suits fit, and age. I think that's one of the reasons mfg's don't list the wetsuit buoyancy in their specs, because it'll change depending on how it fits.

From prior discussions on suit compression, scuba and more industrial scuba wetsuit material does resist this, past some compression point within the rec range. But you also can tip over to the point where the remaining air size is not more significant than the fact that the actual rubber is denser than the water. A suit of mostly solid rubber with only tiny air bubbles left is negative. To actually know, you would need to measure, or understand the details of the material.

That is really the only way would be in interesting experiment to try at depth. I wonder how the best way to do it would be? Measuring the volume of air in a wing/lift bag would be difficult, and I'm unsure if slowly removing all weights would be sufficient to find neutral buoyancy with an empty wing. Maybe a spring scale between two divers?

 

[DiveClimbRide]

100% agree it is not going to be a linear relationship with the neoprene "reinforcing" the air bubbles, and it will depend on the specific neoprene, the suits fit, and age. I think that's one of the reasons mfg's don't list the wetsuit buoyancy in their specs, because it'll change depending on how it fits.



That is really the only way would be in interesting experiment to try at depth. I wonder how the best way to do it would be? Measuring the volume of air in a wing/lift bag would be difficult, and I'm unsure if slowly removing all weights would be sufficient to find neutral buoyancy with an empty wing. Maybe a spring scale between two divers?

Probably easiest to fine tune weights on exhale. Use 100/50g lead sinkers

 

[Jim Lapenta]

The belt should also go on under the crotch strap. Not over it.

 

[Jim Lapenta]

I agree with weight belt being easier to put on in the boat, thats why I would like to have the weight belt under the crotch strap. Do you wear a weight belt under the crotch strap now? To me needing to removing the crotch strap to remove a weight belt is problematic. It makes ditching in an emergency a lot more complicated with and I've also noticed how a full-ish wing wants to float away from you without a crotch strap on the surface, and I would imagine the same thing would happen underwater and make things difficult.

To me the "best" solution would be a weight belt or harness with ditchable pouches worn under the crotch strap, which would afford the best of both worlds, with being just a bit more bulky. However, the DUI harnesses are pricey and probably overkill for the amount of weight I'm talking about.

It seems like a $30 rubber belt and bolting some weights to the backplate may be good enough... If I can keep it to 8-10lbs that will be much easier to handle in the water.

It doesn't make it more difficult. Undo the waist belt, undo the weight belt buckle and it falls away. Position the waist belt buckle slightly off-center to the left so that the crotch strap is over the webbing only and doesn't have to go over the buckle. In an emergency, if you had an issue and I was a rescuer, I wouldn't be messing with buckles anyway. My EezyCut would make short work of your crotch strap and shoulder harness anyway.
In my rescue classes I always have the last scenario where the students have to cut me out of my harness that build specifically for the purpose. it costs me 12 bucks worth of webbing to replace. Or less.
The other option I have seen and played with is a crotch strap with a quick-release buckle. I have one on my HOG back inflate BC. Less than half a second to undo the release and pop the weight belt. I only use the MAKO rubber freediving belts. The loop stays on the waist strap, and everything falls away neatly.

 

[rx7diver]

The belt should also go on under the crotch strap. Not over it.

For recreational diving in a wetsuit, I don't agree with this advice, in general. In general, I think this advice is less than sound.

Absolutely nothing should impede the dropping of the weight belt. In an emergency, when a weight belt should be ditched NOW, every additional step adds risk. Even a rescuer who is unfamiliar with someone's particular "personalized" gear configuration, and who might not have a cutting tool at hand, immediately should be able to locate and drop someone's weight belt.

"Weight belt last on!" used to be the "rule" that was taught. This rule figuratively means "no straps--no nothing--over the weight belt!" For wetsuit, recreational diving, I think this remains a good rule.

Build the weight belt "symmetrically", so that the buckle won't "wander" from center, from where it is "expected" to be located. (A rubber weight belt is less prone to wander, generally.)

And rethink anything that might "catch" the weight belt when it is released, and therefore prevent it from falling away "cleanly." (So, move that knife from the outside of your calf, to the inside, for example. And how likely is it that the reel attached to your DSMB will "catch" your falling weight belt? And how likely is it that the umbilical on your canister light might "catch" your falling weight belt?)

Don't forget the basics.

Caveat: I am NOT an instructor of any stripe.

rx7diver

 

[johndiver999]

I agree with weight belt being easier to put on in the boat, thats why I would like to have the weight belt under the crotch strap. Do you wear a weight belt under the crotch strap now? To me needing to removing the crotch strap to remove a weight belt is problematic. It makes ditching in an emergency a lot more complicated with and I've also noticed how a full-ish wing wants to float away from you without a crotch strap on the surface, and I would imagine the same thing would happen underwater and make things difficult.

To me the "best" solution would be a weight belt or harness with ditchable pouches worn under the crotch strap, which would afford the best of both worlds, with being just a bit more bulky. However, the DUI harnesses are pricey and probably overkill for the amount of weight I'm talking about.

It seems like a $30 rubber belt and bolting some weights to the backplate may be good enough... If I can keep it to 8-10lbs that will be much easier to handle in the water.

I wear a weight belt under the crotch strap. I was initially nervous about it, because it does affect the ability to ditch the belt.

However, I am now comfortable with it for a variety of reasons. One is that I rig the BC waist strap like Jim L recommends with the loop of the crotch strap in front of the waist buckle. So when the harness waist buckle is popped open, then the crotch strap loop falls off and is unconstrained.

I have seen most recommendations to do it otherwise and have the crotch strap also retained by the buckle. That seemed dangerous and without any value for any kind of diving I want to do.

In addition, and because I am concerned about the crotch strap and weight belt issue, I have rigged the crotch strap loop with a fastex buckle. So I could choose to pop the fastex buckle, the crotch strap will fall away from the front and I don't need to open the waist strap on the BC harness at all.

I have experimented and generally if you decide to pop open the BC waist strap, the BCor BP/W is not going to fly off your body, it will just ride up a little and feel dorky.. not a big deal at all. If you do it at the surface and have a modest amount of air in the BC, the result is actually pretty minor.

In fact, think about what happens when you normally take off a Scuba unit with a BC on it at the surface. After removing the weight belt, you then pop open the waist strap and then slip your arms out or open a shoulder strap buckle. When you are doing this, is it a big problem for the few moments when you are wearing the BC unit with no waist strap attached? Not really.

If you are going to drop a weightbelt while at depth, think about the circumstances that would warrant that action....IF your BC was working and was inflated, then why would you be ditching lead? Answer is.. you probably wouldn't be dropping a belt.

IF your BC failed and you had to drop ballast (weight belt) to initiate an ascent, then almost by definition, your BC or Wing would be empty or containing little air; so even dropping the belt at depth is not going to be a big problem if you have to first open your harness waist strap - because the rig will be neutral or negative and will just sit on your back.

I can understand the idea of a weight belt being last on and first off, but in practice, you can be proficient in removing the weight belt by releasing the crotch strap. I am not a fan of pouches holding lead on the BP/W harness.

The thing to remember is that the proper way to remove a weight belt it NOT to pop the buckle and let it passively fall down when wearing scuba gear. It can be trapped on portions of the harness or get caught on a knife or even wrap around your foot for a few moments.

The proper technique is to open the buckle and then PULL the weightbelt forward and away from your body and when it is in front of you and clearly unentangled, to release it. If you are proficient and comfortable with that technique, then the prerequisite of releasing a crotch strap, is pretty inconsequential.

 

[Thunter96]

IF your BC failed and you had to drop ballast (weight belt) to initiate an ascent, then almost by definition, your BC or Wing would be empty or containing little air; so even dropping the belt at depth is not going to be a big problem if you have to first open your harness waist strap - because the rig will be neutral or negative and will just sit on your back.

I can understand the idea of a weight belt being last on and first off, but in practice, you can be proficient in removing the weight belt by releasing the crotch strap. I am not a fan of pouches holding lead on the BP/W harness.

That's a good point, my one experience with a belt worn underneath was with a pretty full wing on the surface, and being the first time doing this I just wasn't expecting it to fly backwards. I initially was thinking of taking off my weight belt 1st to put in the boat since I was wearing 20#s of lead which would mean treading water to keep my head up. Less weight on the belt and won't need to tread.

Why are you not a fan of wearing pouches for lead on the BP/W? Wouldn't need to worry about the crotch strap at all, and if the pouches have an inner pouch, that would be easy to remove in and out of the water to dump in the boat. These XDEEP pockets look pretty good. Weight pockets M for SCUBA diving BC system - XDEEP

The whole rig would be pretty heavy, but when I want the rig to be light I could remove the lead and drop it in the boat separately.

It doesn't make it more difficult. Undo the waist belt, undo the weight belt buckle and it falls away. Position the waist belt buckle slightly off-center to the left so that the crotch strap is over the webbing only and doesn't have to go over the buckle. In an emergency, if you had an issue and I was a rescuer, I wouldn't be messing with buckles anyway. My EezyCut would make short work of your crotch strap and shoulder harness anyway.

Yeah it is just one more extra step, not really much more complicated. More concerned about how I would go about it in a hurry rather than a rescue diver. What is the rationale for wearing it under? My reason for wanting to wear it that way would be so I could put in on, throw my kit out the inflatable and put it on in the water.