Weights with sidemount?

[SanDiegoSidemount]

I am a bit of a safety nut in diving so I have a dual bladder bc and a drysuit (most dives) and I also carry a lift bag. For those few dives I dive wet with my steel tanks I will still have the dual bladder and lift bag so as long as I know how to handle them in an emergency that should work for me.

Diving dry with dual bladders and a lift bag I'd have to say you're pretty darn safe with no ditchable at all.

Wetsuit with single bladder (which I sometimes do) then I think it's prudent to do the math and have some weight you can ditch. I don't dive wet below 60 feet either.

 

[rjack321]

I have 13lbs fixed up between my shoulder blades. Then:
In freshwater I have 6lbs on a weightbelt. I would prefer if its were NOT ditchable being in a cave. But I need the weight 'south' and there's no place else down there to put it.

I occasionally dive SM in open (salt) water and have 12 on a weightbelt for that. It's not really ditchable underneath a crotch strap and the tanks however. I only dive dry so having detachable weight isn't critical.

 

[Razorista]

Ditchable weight seems superfluous to me in sidemount anyway - dangerous actually.

Dropping one or two lbs of lead will not help more than ascending on fins and lung alone and anyone could manage that easily, and double that with a manageable and temporary effort.
Dropping more than 4 often cannot be controlled a few feet closer to the surface even for a short time.

The only use seems being able to dive over-weighted with an unnecessarily over-inflated BCD and no redundancy.

Sidemount beginners in particular move around so much they could reasonably dislodge a weight pocket and drop it by accident.
Maybe I am paranoid there, but not having ditchable weight is an advantage in my opinion - perhaps excluding some very specialized equipment configurations and situations.

 

[Jim Lapenta]

I think the concept of ALWAYS having ditchable weight is exacerbated by the all too common practice of overweighting divers to begin with. If the concept of a balanced rig was taught to new divers right off the bat we would not see so much of this carried over into later training. Heck if they were just taught to do proper checks repeatedly in the OW class on their own we would not see it. But it's so much easier to hand a student a belt with whatever on it and say "here, this should be enough" as I have seen many times and the student, blissfully ignorant, just accepts that. I have done a number of weight and trim workshops where in less than two hours have had or been able to get rid of 25% of what the diver was carrying based on their OW instructors advice or practice. Some even more than that.

Sent from my DROID X2 using Tapatalk 2

 

[Subcooled]

Hmmm. I personally would find it a bit scary to consider part my life support system as "ditchable" weight. Is this really taught or endorsed by anyone

In a case of emergency, dump all air to float up

OK, enough joking. The question is valid. Mandatory stops also complicate things. Let's get serious:

Endorsed by anyone? Probably not. It would be a desperate deed best avoided. I dive mostly in mines, and also under ice, so inadvertent dropping of weights is really not an option, and I have tried to make sure that the weights stay with me no matter what happens. There are other more controlled ways to reach the surface.

There are a few failure modes that are relevant to open circuit scuba:

1) loss of existing buoyancy: torn bcd bladder, flooded drysuit, ...
2) loss of bcd inflation during descent
3) drifting at sea

A second big enough independent bcd protects in case 1. It is quite unlikely that one would loose both a drysuit and a wing (or two independent wings) simultaneously. I mean that they would start leaking at the same time...

The second case is a nasty one. A few scenarios that I can think of are a) running out of air in both cylinders during descent. Also, b) two burst LP hoses, c) or two burst tank o-rings, d) two first stages freezing shut at the same time, or some other dual failure could lead to uncontrolled descent. None of these situations seem very probable. Descending extremely fast could lead to problems (of not beeing able to inflate a wing fast enough - there was another thread about this). We avoid this by descending slowly, right?

One should be facing and communicating with a team member throughout the descent, in any case. Descent is the most dangerous part of the dive. Unfortunately, many commence "team solo descents", and often overweighted. It is a very dangerous practice that has killed people.

I don't dive at sea so #3 is not relevant in my case. Ok, I admit: I have been to the sea twice in sidemount gear. I did carry 4 pounds of droppable weight in the front on my waist belt. It is not a lot, but it's something. I would have needed to open the belt buckle though, to drop that.

losing all your trim buoyancy early in a dive at max depth, then ditching enough to be able to swim up to your deco stop(s) and hold them.

This sounds like a single bcd bladder scenario. No-one in their right minds would dive without droppable weights (and the mental state required to actually drop a weight - do practice it) using a single bcd bladder only. We have all seen the video of the last dive of Yuri Lipski, haven't we?

 

[Colliam7]

If I need to ditch weight the dive is over and if I drop one tank I still have a complete "life support" system on my other side. That is the point of redundant gas supplies and regs.

Hmmm. I personally would find it a bit scary to consider part my life support system as "ditchable" weight. Is this really taught or endorsed by anyone, or is it simply one of those things we say to convince ourselves we are safe to carry no other form of ditchable weight?

Yes, I teach it - as one contingency (and, certainly not the only) available to a diver in the event of a buoyancy failure that compromises their ability to reach the surface. As Jim points out, that is a benefit of the sidemount configuration - independent gas supplies. So, it is not just something we cavalierly say to convince ourselves that carrying no ditchable weight is OK.

Having said this, the combination of circumstances under which ditching a cylinder at depth would become necessary is rather unlikely. And, if you ditch a cylinder, you could conceivably become uncontrollably positive, which presents an entirely different, but equally challenging set of circumstances. (Of course, if you are so over-weighted that ditching a cylinder becomes necessary, that might not be the case.) Ditching a cylinder at the surface, to establish positive buoyancy in and emergency - I would not hesitate to do so.

I have never had to ditch weight (either added lead, or a cylinder) to be able to reach the surface - I cannot say from first hand, real-life experience that it is ideal. But, I practice the cylinder ditch skill (albeit not under conditions of a total buoyancy failure), just as I practice swimming BM doubles, and singles to the surface with an empty BCD, in order to know what I am capable (or not) of doing.

So, is it taught / endorsed, as one possible course of action? Yes. What is probably more important is something that you later acknowledged - there are few absolutes. Therefore, I would not take the position that I would ABSOLUTELY NOT ditch a cylinder under certain conditions, if that was the only way to reach the surface.

 

[Subcooled]

It is also worth remembering that equipment never used will not be used in an emergency either.
Ditching weights is only possible after regular practice and mental preparedness.

This is not a feel good movie
https://www.youtube.com/watch?v=eejQPUyeNiY

 

[rick00001967]

Dropping one or two lbs of lead will not help more than ascending on fins and lung alone and anyone could manage that easily, and double that with a manageable and temporary effort.
Dropping more than 4 often cannot be controlled a few feet closer to the surface even for a short time.

The only use seems being able to dive over-weighted with an unnecessarily over-inflated BCD and no redundancy.

i am certainly no tech diver, but this is exactly what i was thinkin