Question about “balanced rigs” and having all ballast unditchable

[Akimbo]

The buoyancy of the rig is easy to find in the pool and convert.

True, when you use exactly the same rented gear in the pool as in the ocean and the pool is cold enough that students don't pass out from hyperthermia.

 

[MichaelMc]

True, when you use exactly the same rented gear in the pool as in the ocean and the pool is cold enough that students don't pass out from hyperthermia.

I mean pool measuring just the BC and attached tank/gear, thought rental BCs between pool and ocean might differ..., or in tbone's case I think the pool is BP/W and ocean is local shop rental so they experience that. A school should have a good idea of the buoyancy of the BCs and tank/reg combos they use in ocean; should not will.

I was thinking to take body and wetsuit out of the equation and let them be measured in ocean in a cleaner setup than with the whole BC and tank. And 'prep your rigs, and then we'll jump in the ocean slick' is not a bad trial run on entry. But this plan does require big enough belts for the needed lead. That might be one place it gets hard.

 

[CT-Rich]

I mean pool measuring just the BC and attached tank/gear, thought rental BCs between pool and ocean might differ..., or in tbone's case I think the pool is BP/W and ocean is local shop rental so they experience that. A school should have a good idea of the buoyancy of the BCs and tank/reg combos they use in ocean; should not will.

I was thinking to take body and wetsuit out of the equation and let them be measured in ocean in a cleaner setup than with the whole BC and tank. And 'prep your rigs, and then we'll jump in the ocean slick' is not a bad trial run on entry. But this plan does require big enough belts for the needed lead. That might be one place it gets hard.

The biggest variable is the wetsuit combined with the typical pear shape OW student, that combine with the variability of the equipment is wha requires dialing in. No empty BCD with a full tank will most likely sink, that why warm water divers don’t necessarily need weights. A doughy hausfrau will not have the same characteristics as the 25 year old triathlete. It does not lend itself to formulaic calculations.

There is a reason there are classes devoted to peak buoyancy.. there is also a reason why divers as they gain experience shed weight,

 

[MichaelMc]

The biggest variable is the wetsuit combined with the typical pear shape OW student, that combine with the variability of the equipment is wha requires dialing in. No empty BCD with a full tank will most likely sink, that why warm water divers don’t necessarily need weights. A doughy hausfrau will not have the same characteristics as the 25 year old triathlete. It does not lend itself to formulaic calculations.

There is a reason there are classes devoted to peak buoyancy.. there is also a reason why divers as they gain experience shed weight,

Ah. I'm suggesting empirical measurement, not formulaic. Unless you count multiplying by salt-density/fresh-density as formulaic. They used some BC and tank in class, standing at pool side hang it from a weight scale in the water to see what would make it neutral and account for its gas. If something is neutral in the pool and weights X pounds on land, then it needs X * salt-density / fresh-density extra lead to be neutral in the ocean. Any OW student, much less their instructors, should be able to do that math. Which is why I say that part isn't hard. If students are always in the same BC/tank/regs, just remember those numbers.

Yeah Fred or Sally and their random wetsuit are a big unknown. But they've been in a great freshwater buoyancy measuring device, aka a pool, for 4 sessions. Attached to a BC/tank/reg whose buoyancy we know. Estimate from that but take them outside the surf zone for a trial weight run without the BC and tank. Your only left guessing on how much their ocean suit changes the situation.

 

[CT-Rich]

Ah. I'm suggesting empirical measurement, not formulaic. Unless you count multiplying by salt-density/fresh-density as formulaic. They used some BC and tank in class, standing at pool side hang it from a weight scale in the water to see what would make it neutral and account for its gas. If something is neutral in the pool and weights X pounds on land, then it needs X * salt-density / fresh-density extra lead to be neutral in the ocean. Any OW student, much less their instructors, should be able to do that math. Which is why I say that part isn't hard. If students are always in the same BC/tank/regs, just remember those numbers.

Yeah Fred or Sally and their random wetsuit are a big unknown. But they've been in a great freshwater buoyancy measuring device, aka a pool, for 4 sessions. Attached to a BC/tank/reg whose buoyancy we know. Estimate from that but take them outside the surf zone for a trial weight run without the BC and tank. Your only left guessing on how much their ocean suit changes the situation.

Ahhh.... A best guess... Like they were doing before?

 

[Landlocked123]

So I switched to a wing and back plate right after OW years ago. I have no weight to ditch. I am also "balanced" meaning I am able to swing my rig up (no air in BCD) - tested it at 60 feet. A little work at first but since I dive wet with a 7mil once I get to that 30 foot range it becomes very very easy. I HATE a weight belt. Dont like the feel, dont link the trim characteristics. The feeling just sucked. My trim is good and so is my buoyancy ( at least my instructor friends tell me so). If I had to get to the surface I can, I carry 2 SMB's. One larger one smaller. Each are readily deploy-able and accessible within easy reach (budgie tied to my back-plate on either side- they are there for other reasons but could be used as flotation) I am definitely 2-3 lbs over weighted due to the STA but again not a major issue as I can easily tread water with no air in the BC. Do I sink if I stay completely motionless = yes but very slowly. If I ever got left behind by the dive boat I could float till next week effortless due to the redundant lift I carry. So what i am saying is that I think one can achieve a "balanced" rig with or without "ditchable" weight. Why do I have to have ditchable weight? I think its also a matter of cutting both ways. So far the only true "emergencies" I saw diving is folks dropping their weight belts by accident and rocketing to the surface like a cruise missile. No one seems to discuss that aspect but instead we talk about wing failure constantly as if its just around the corner. Bottom line if you can swing you rig up from the deeper dives that you do I don't see the issue and why I should have "ditchable weights". What am I missing?

 

[MichaelMc]

So I switched to a wing and back plate right after OW years ago.

Out of curiosity, do you have an aluminum or steel plate?

 

[Landlocked123]

Steel both backplate and STA. Dive Steel HP 100 or 133 depending.

 

[MichaelMc]

I am definitely 2-3 lbs over weighted due to the STA but again not a major issue as I can easily tread water with no air in the BC.

Steel both backplate and STA. Dive Steel HP 100 or 133 depending.

It looks like if you switched to a aluminum plate you would drop 5 lb. from the plate. So you could fix being overweighted 2-3 lb., and free a few pounds for integrated ditchable pockets. Setting aside any tank changes. Dropping a heavy belt can definitely produce a missile, though flaring your body is surprisingly effective. Dropping a modest 6-8 lb. belt is not nearly as dramatic in dire consequence. Losing one of two integrated pockets, with only 3-4 lb in it is rather less alarming still. People are not arguing about concern ascending from depth, but rather about staying on the surface once you get there. If your exhausted, injured, and in chop, do you want to pull out your SMBs inflate and hold them? Or just ditch two integrated pockets as a start? Just something to think about.

 

[Landlocked123]

I guess it depends on the type of diving one does. I wreck dive the Carolina's from time to time but most of my diving is quarry diving ...landlocked...quite literally ! LOL. I guess if I ever switched to mostly ocean dives something to consider.